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diff --git a/doc/rfc/rfc4949.txt b/doc/rfc/rfc4949.txt new file mode 100644 index 0000000..7de0187 --- /dev/null +++ b/doc/rfc/rfc4949.txt @@ -0,0 +1,20443 @@ + + + + + + +Network Working Group R. Shirey +Request for Comments: 4949 August 2007 +FYI: 36 +Obsoletes: 2828 +Category: Informational + + + Internet Security Glossary, Version 2 + +Status of This Memo + + This memo provides information for the Internet community. It does + not specify an Internet standard of any kind. Distribution of this + memo is unlimited. + +Copyright Notice + + Copyright (C) The IETF Trust (2007). + +RFC Editor Note + + This document is both a major revision and a major expansion of the + Security Glossary in RFC 2828. This revised Glossary is an extensive + reference that should help the Internet community to improve the + clarity of documentation and discussion in an important area of + Internet technology. However, readers should be aware of the + following: + + (1) The recommendations and some particular interpretations in + definitions are those of the author, not an official IETF position. + The IETF has not taken a formal position either for or against + recommendations made by this Glossary, and the use of RFC 2119 + language (e.g., SHOULD NOT) in the Glossary must be understood as + unofficial. In other words, the usage rules, wording interpretations, + and other recommendations that the Glossary offers are personal + opinions of the Glossary's author. Readers must judge for themselves + whether or not to follow his recommendations, based on their own + knowledge combined with the reasoning presented in the Glossary. + + (2) The glossary is rich in the history of early network security + work, but it may be somewhat incomplete in describing recent security + work, which has been developing rapidly. + + + + + + + + + +Shirey Informational [Page 1] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + +Abstract + + This Glossary provides definitions, abbreviations, and explanations + of terminology for information system security. The 334 pages of + entries offer recommendations to improve the comprehensibility of + written material that is generated in the Internet Standards Process + (RFC 2026). The recommendations follow the principles that such + writing should (a) use the same term or definition whenever the same + concept is mentioned; (b) use terms in their plainest, dictionary + sense; (c) use terms that are already well-established in open + publications; and (d) avoid terms that either favor a particular + vendor or favor a particular technology or mechanism over other, + competing techniques that already exist or could be developed. + +Table of Contents + + 1. Introduction ....................................................3 + 2. Format of Entries ...............................................4 + 2.1. Order of Entries ...........................................4 + 2.2. Capitalization and Abbreviations ...........................5 + 2.3. Support for Automated Searching ............................5 + 2.4. Definition Type and Context ................................5 + 2.5. Explanatory Notes ..........................................6 + 2.6. Cross-References ...........................................6 + 2.7. Trademarks .................................................6 + 2.8. The New Punctuation ........................................6 + 3. Types of Entries ................................................7 + 3.1. Type "I": Recommended Definitions of Internet Origin .......7 + 3.2. Type "N": Recommended Definitions of Non-Internet Origin ...8 + 3.3. Type "O": Other Terms and Definitions To Be Noted ..........8 + 3.4. Type "D": Deprecated Terms and Definitions .................8 + 3.5. Definition Substitutions ...................................8 + 4. Definitions .....................................................9 + 5. Security Considerations .......................................343 + 6. Normative Reference ...........................................343 + 7. Informative References ........................................343 + 8. Acknowledgments ...............................................364 + + + + + + + + + + + + + + +Shirey Informational [Page 2] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + +1. Introduction + + This Glossary is *not* an Internet Standard, and its recommendations + represent only the opinions of its author. However, this Glossary + gives reasons for its recommendations -- especially for the SHOULD + NOTs -- so that readers can judge for themselves what to do. + + This Glossary provides an internally consistent and self-contained + set of terms, abbreviations, and definitions -- supported by + explanations, recommendations, and references -- for terminology that + concerns information system security. The intent of this Glossary is + to improve the comprehensibility of written materials that are + generated in the Internet Standards Process (RFC 2026) -- i.e., RFCs, + Internet-Drafts, and other items of discourse -- which are referred + to here as IDOCs. A few non-security, networking terms are included + to make the Glossary self-contained, but more complete glossaries of + such terms are available elsewhere [A1523, F1037, R1208, R1983]. + + This Glossary supports the goals of the Internet Standards Process: + + o Clear, Concise, Easily Understood Documentation + + This Glossary seeks to improve comprehensibility of security- + related content of IDOCs. That requires wording to be clear and + understandable, and requires the set of security-related terms and + definitions to be consistent and self-supporting. Also, + terminology needs to be uniform across all IDOCs; i.e., the same + term or definition needs to be used whenever and wherever the same + concept is mentioned. Harmonization of existing IDOCs need not be + done immediately, but it is desirable to correct and standardize + terminology when new versions are issued in the normal course of + standards development and evolution. + + o Technical Excellence + + Just as Internet Standard (STD) protocols should operate + effectively, IDOCs should use terminology accurately, precisely, + and unambiguously to enable standards to be implemented correctly. + + o Prior Implementation and Testing + + Just as STD protocols require demonstrated experience and + stability before adoption, IDOCs need to use well-established + language; and the robustness principle for protocols -- "be + liberal in what you accept, and conservative in what you send" -- + is also applicable to the language used in IDOCs that describe + protocols. Using terms in their plainest, dictionary sense (when + appropriate) helps to make them more easily understood by + + + +Shirey Informational [Page 3] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + international readers. IDOCs need to avoid using private, newly + invented terms in place of generally accepted terms from open + publications. IDOCs need to avoid substituting new definitions + that conflict with established ones. IDOCs need to avoid using + "cute" synonyms (e.g., "Green Book"), because no matter how + popular a nickname may be in one community, it is likely to cause + confusion in another. + + However, although this Glossary strives for plain, internationally + understood English language, its terms and definitions are biased + toward English as used in the United States of America (U.S.). + Also, with regard to terminology used by national governments and + in national defense areas, the glossary addresses only U.S. usage. + + o Openness, Fairness, and Timeliness + + IDOCs need to avoid using proprietary and trademarked terms for + purposes other than referring to those particular systems. IDOCs + also need to avoid terms that either favor a particular vendor or + favor a particular security technology or mechanism over other, + competing techniques that already exist or might be developed in + the future. The set of terminology used across the set of IDOCs + needs to be flexible and adaptable as the state of Internet + security art evolves. + + In support of those goals, this Glossary offers guidance by marking + terms and definitions as being either endorsed or deprecated for use + in IDOCs. The key words "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", + and "OPTIONAL" are intended to be interpreted the same way as in an + Internet Standard (i.e., as specified in RFC 2119 [R2119]). Other + glossaries (e.g., [Raym]) list additional terms that deal with + Internet security but have not been included in this Glossary because + they are not appropriate for IDOCs. + +2. Format of Entries + + Section 4 presents Glossary entries in the following manner: + +2.1. Order of Entries + + Entries are sorted in lexicographic order, without regard to + capitalization. Numeric digits are treated as preceding alphabetic + characters, and special characters are treated as preceding digits. + Blanks are treated as preceding non-blank characters, except that a + hyphen or slash between the parts of a multiword entry (e.g., + "RED/BLACK separation") is treated like a blank. + + + + + +Shirey Informational [Page 4] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + If an entry has multiple definitions (e.g., "domain"), they are + numbered beginning with "1", and any of those multiple definitions + that are RECOMMENDED for use in IDOCs are presented before other + definitions for that entry. If definitions are closely related (e.g., + "threat"), they are denoted by adding letters to a number, such as + "1a" and "1b". + +2.2. Capitalization and Abbreviations + + Entries that are proper nouns are capitalized (e.g., "Data Encryption + Algorithm"), as are other words derived from proper nouns (e.g., + "Caesar cipher"). All other entries are not capitalized (e.g., + "certification authority"). Each acronym or other abbreviation that + appears in this Glossary, either as an entry or in a definition or + explanation, is defined in this Glossary, except items of common + English usage, such as "a.k.a.", "e.g.", "etc.", "i.e.", "vol.", + "pp.", and "U.S.". + +2.3. Support for Automated Searching + + Each entry is preceded by a dollar sign ($) and a space. This makes + it possible to find the defining entry for an item "X" by searching + for the character string "$ X", without stopping at other entries in + which "X" is used in explanations. + +2.4. Definition Type and Context + + Each entry is preceded by a character -- I, N, O, or D -- enclosed in + parentheses, to indicate the type of definition (as is explained + further in Section 3): + - "I" for a RECOMMENDED term or definition of Internet origin. + - "N" if RECOMMENDED but not of Internet origin. + - "O" for a term or definition that is NOT recommended for use in + IDOCs but is something that authors of Internet documents should + know about. + - "D" for a term or definition that is deprecated and SHOULD NOT be + used in Internet documents. + + If a definition is valid only in a specific context (e.g., + "baggage"), that context is shown immediately following the + definition type and is enclosed by a pair of slash symbols (/). If + the definition is valid only for specific parts of speech, that is + shown in the same way (e.g., "archive"). + + + + + + + + +Shirey Informational [Page 5] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + +2.5. Explanatory Notes + + Some entries have explanatory text that is introduced by one or more + of the following keywords: + - Deprecated Abbreviation (e.g., "AA") + - Deprecated Definition (e.g., "digital certification") + - Deprecated Usage (e.g., "authenticate") + - Deprecated Term (e.g., "certificate authority") + - Pronunciation (e.g., "*-property") + - Derivation (e.g., "discretionary access control") + - Tutorial (e.g., "accreditation") + - Example (e.g., "back door") + - Usage (e.g., "access") + + Explanatory text in this Glossary MAY be reused in IDOCs. However, + this text is not intended to authoritatively supersede text of an + IDOC in which the Glossary entry is already used. + +2.6. Cross-References + + Some entries contain a parenthetical remark of the form "(See: X.)", + where X is a list of other, related terms. Some entries contain a + remark of the form "(Compare: X)", where X is a list of terms that + either are antonyms of the entry or differ in some other manner worth + noting. + +2.7. Trademarks + + All servicemarks and trademarks that appear in this Glossary are used + in an editorial fashion and to the benefit of the mark owner, without + any intention of infringement. + +2.8. The New Punctuation + + This Glossary uses the "new" or "logical" punctuation style favored + by computer programmers, as described by Raymond [Raym]: Programmers + use pairs of quotation marks the same way they use pairs of + parentheses, i.e., as balanced delimiters. For example, if "Alice + sends" is a phrase, and so are "Bill receives" and "Eve listens", + then a programmer would write the following sentence: + + "Alice sends", "Bill receives", and "Eve listens". + + According to standard American usage, the punctuation in that + sentence is incorrect; the continuation commas and the final period + should go inside the string quotes, like this: + + "Alice sends," "Bill receives," and "Eve listens." + + + +Shirey Informational [Page 6] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + However, a programmer would not include a character in a literal + string if the character did not belong there, because that could + cause an error. For example, suppose a sentence in a draft of a + tutorial on the vi editing language looked like this: + + Then delete one line from the file by typing "dd". + + A book editor following standard usage might change the sentence to + look like this: + + Then delete one line from the file by typing "dd." + + However, in the vi language, the dot character repeats the last + command accepted. So, if a reader entered "dd.", two lines would be + deleted instead of one. + + Similarly, use of standard American punctuation might cause + misunderstanding in entries in this Glossary. Thus, the new + punctuation is used here, and we recommend it for IDOCs. + +3. Types of Entries + + Each entry in this Glossary is marked as type I, N, O, or D: + +3.1. Type "I": Recommended Definitions of Internet Origin + + The marking "I" indicates two things: + - Origin: "I" (as opposed to "N") means either that the Internet + Standards Process or Internet community is authoritative for the + definition *or* that the term is sufficiently generic that this + Glossary can freely state a definition without contradicting a + non-Internet authority (e.g., "attack"). + - Recommendation: "I" (as opposed to "O") means that the term and + definition are RECOMMENDED for use in IDOCs. However, some "I" + entries may be accompanied by a "Usage" note that states a + limitation (e.g., "certification"), and IDOCs SHOULD NOT use the + defined term outside that limited context. + + Many "I" entries are proper nouns (e.g., "Internet Protocol") for + which the definition is intended only to provide basic information; + i.e., the authoritative definition of such terms is found elsewhere. + For a proper noun described as an "Internet protocol", please refer + to the current edition of "Internet Official Protocol Standards" + (Standard 1) for the standardization status of the protocol. + + + + + + + +Shirey Informational [Page 7] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + +3.2. Type "N": Recommended Definitions of Non-Internet Origin + + The marking "N" indicates two things: + - Origin: "N" (as opposed to "I") means that the entry has a non- + Internet basis or origin. + - Recommendation: "N" (as opposed to "O") means that the term and + definition are RECOMMENDED for use in IDOCs, if they are needed at + all in IDOCs. Many of these entries are accompanied by a label + that states a context (e.g., "package") or a note that states a + limitation (e.g., "data integrity"), and IDOCs SHOULD NOT use the + defined term outside that context or limit. Some of the contexts + are rarely if ever expected to occur in an IDOC (e.g., "baggage"). + In those cases, the listing exists to make Internet authors aware + of the non-Internet usage so that they can avoid conflicts with + non-Internet documents. + +3.3. Type "O": Other Terms and Definitions To Be Noted + + The marking "O" means that the definition is of non-Internet origin + and SHOULD NOT be used in IDOCs *except* in cases where the term is + specifically identified as non-Internet. + + For example, an IDOC might mention "BCA" (see: brand certification + authority) or "baggage" as an example of some concept; in that case, + the document should specifically say "SET(trademark) BCA" or + "SET(trademark) baggage" and include the definition of the term. + +3.4. Type "D": Deprecated Terms and Definitions + + If this Glossary recommends that a term or definition SHOULD NOT be + used in IDOCs, then the entry is marked as type "D", and an + explanatory note -- "Deprecated Term", "Deprecated Abbreviation", + "Deprecated Definition", or "Deprecated Usage" -- is provided. + +3.5. Definition Substitutions + + Some terms have a definition published by a non-Internet authority -- + a government (e.g., "object reuse"), an industry (e.g., "Secure Data + Exchange"), a national authority (e.g., "Data Encryption Standard"), + or an international body (e.g., "data confidentiality") -- that is + suitable for use in IDOCs. In those cases, this Glossary marks the + definition "N", recommending its use in Internet documents. + + Other such terms have definitions that are inadequate or + inappropriate for IDOCs. For example, a definition might be outdated + or too narrow, or it might need clarification by substituting more + careful wording (e.g., "authentication exchange") or explanations, + using other terms that are defined in this Glossary. In those cases, + + + +Shirey Informational [Page 8] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + this Glossary marks the entry "O", and provides an "I" or "N" entry + that precedes, and is intended to supersede, the "O" entry. + + In some cases where this Glossary provides a definition to supersede + an "O" definition, the substitute is intended to subsume the meaning + of the "O" entry and not conflict with it. For the term "security + service", for example, the "O" definition deals narrowly with only + communication services provided by layers in the OSIRM and is + inadequate for the full range of IDOC usage, while the new "I" + definition provided by this Glossary can be used in more situations + and for more kinds of service. However, the "O" definition is also + listed so that IDOC authors will be aware of the context in which the + term is used more narrowly. + + When making substitutions, this Glossary attempts to avoid + contradicting any non-Internet authority. Still, terminology differs + between authorities such as the American Bar Association, OSI, SET, + the U.S. DoD, and other authorities; and this Glossary probably is + not exactly aligned with any of them. + +4. Definitions + + $ *-property + (N) Synonym for "confinement property" in the context of the Bell- + LaPadula model. Pronunciation: star property. + + $ 3DES + (N) See: Triple Data Encryption Algorithm. + + $ A1 computer system + (O) /TCSEC/ See: Tutorial under "Trusted Computer System + Evaluation Criteria". (Compare: beyond A1.) + + $ AA + (D) See: Deprecated Usage under "attribute authority". + + $ ABA Guidelines + (N) "American Bar Association (ABA) Digital Signature Guidelines" + [DSG], a framework of legal principles for using digital + signatures and digital certificates in electronic commerce. + + $ Abstract Syntax Notation One (ASN.1) + (N) A standard for describing data objects. [Larm, X680] (See: + CMS.) + + Usage: IDOCs SHOULD use the term "ASN.1" narrowly to describe the + notation or language called "Abstract Syntax Notation One". IDOCs + MAY use the term more broadly to encompass the notation, its + + + +Shirey Informational [Page 9] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + associated encoding rules (see: BER), and software tools that + assist in its use, when the context makes this meaning clear. + + Tutorial: OSIRM defines computer network functionality in layers. + Protocols and data objects at higher layers are abstractly defined + to be implemented using protocols and data objects from lower + layers. A higher layer may define transfers of abstract objects + between computers, and a lower layer may define those transfers + concretely as strings of bits. Syntax is needed to specify data + formats of abstract objects, and encoding rules are needed to + transform abstract objects into bit strings at lower layers. OSI + standards use ASN.1 for those specifications and use various + encoding rules for those transformations. (See: BER.) + + In ASN.1, formal names are written without spaces, and separate + words in a name are indicated by capitalizing the first letter of + each word except the first word. For example, the name of a CRL is + "certificateRevocationList". + + $ ACC + (I) See: access control center. + + $ acceptable risk + (I) A risk that is understood and tolerated by a system's user, + operator, owner, or accreditor, usually because the cost or + difficulty of implementing an effective countermeasure for the + associated vulnerability exceeds the expectation of loss. (See: + adequate security, risk, "second law" under "Courtney's laws".) + + $ access + 1a. (I) The ability and means to communicate with or otherwise + interact with a system to use system resources either to handle + information or to gain knowledge of the information the system + contains. (Compare: handle.) + + Usage: The definition is intended to include all types of + communication with a system, including one-way communication in + either direction. In actual practice, however, passive users might + be treated as not having "access" and, therefore, be exempt from + most requirements of the system's security policy. (See: "passive + user" under "user".) + + 1b. (O) "Opportunity to make use of an information system (IS) + resource." [C4009] + + 2. (O) /formal model/ "A specific type of interaction between a + subject and an object that results in the flow of information from + one to the other." [NCS04] + + + +Shirey Informational [Page 10] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ Access Certificate for Electronic Services (ACES) + (O) A PKI operated by the U.S. Government's General Services + Administration in cooperation with industry partners. (See: CAM.) + + $ access control + 1. (I) Protection of system resources against unauthorized access. + + 2. (I) A process by which use of system resources is regulated + according to a security policy and is permitted only by authorized + entities (users, programs, processes, or other systems) according + to that policy. (See: access, access control service, computer + security, discretionary access control, mandatory access control, + role-based access control.) + + 3. (I) /formal model/ Limitations on interactions between subjects + and objects in an information system. + + 4. (O) "The prevention of unauthorized use of a resource, + including the prevention of use of a resource in an unauthorized + manner." [I7498-2] + + 5. (O) /U.S. Government/ A system using physical, electronic, or + human controls to identify or admit personnel with properly + authorized access to a SCIF. + + $ access control center (ACC) + (I) A computer that maintains a database (possibly in the form of + an access control matrix) defining the security policy for an + access control service, and that acts as a server for clients + requesting access control decisions. + + Tutorial: An ACC is sometimes used in conjunction with a key + center to implement access control in a key-distribution system + for symmetric cryptography. (See: BLACKER, Kerberos.) + + $ access control list (ACL) + (I) /information system/ A mechanism that implements access + control for a system resource by enumerating the system entities + that are permitted to access the resource and stating, either + implicitly or explicitly, the access modes granted to each entity. + (Compare: access control matrix, access list, access profile, + capability list.) + + $ access control matrix + (I) A rectangular array of cells, with one row per subject and one + column per object. The entry in a cell -- that is, the entry for a + particular subject-object pair -- indicates the access mode that + the subject is permitted to exercise on the object. Each column is + + + +Shirey Informational [Page 11] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + equivalent to an "access control list" for the object; and each + row is equivalent to an "access profile" for the subject. + + $ access control service + (I) A security service that protects against a system entity using + a system resource in a way not authorized by the system's security + policy. (See: access control, discretionary access control, + identity-based security policy, mandatory access control, rule- + based security policy.) + + Tutorial: This service includes protecting against use of a + resource in an unauthorized manner by an entity (i.e., a + principal) that is authorized to use the resource in some other + manner. (See: insider.) The two basic mechanisms for implementing + this service are ACLs and tickets. + + $ access level + 1. (D) Synonym for the hierarchical "classification level" in a + security level. [C4009] (See: security level.) + + 2. (D) Synonym for "clearance level". + + Deprecated Definitions: IDOCs SHOULD NOT use this term with these + definitions because they duplicate the meaning of more specific + terms. Any IDOC that uses this term SHOULD provide a specific + definition for it because access control may be based on many + attributes other than classification level and clearance level. + + $ access list + (I) /physical security/ Roster of persons who are authorized to + enter a controlled area. (Compare: access control list.) + + $ access mode + (I) A distinct type of data processing operation (e.g., read, + write, append, or execute, or a combination of operations) that a + subject can potentially perform on an object in an information + system. [Huff] (See: read, write.) + + $ access policy + (I) A kind of "security policy". (See: access, access control.) + + $ access profile + (O) Synonym for "capability list". + + Usage: IDOCs that use this term SHOULD state a definition for it + because the definition is not widely known. + + + + + +Shirey Informational [Page 12] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ access right + (I) Synonym for "authorization"; emphasizes the possession of the + authorization by a system entity. + + $ accountability + (I) The property of a system or system resource that ensures that + the actions of a system entity may be traced uniquely to that + entity, which can then be held responsible for its actions. [Huff] + (See: audit service.) + + Tutorial: Accountability (a.k.a. individual accountability) + typically requires a system ability to positively associate the + identity of a user with the time, method, and mode of the user's + access to the system. This ability supports detection and + subsequent investigation of security breaches. Individual persons + who are system users are held accountable for their actions after + being notified of the rules of behavior for using the system and + the penalties associated with violating those rules. + + $ accounting See: COMSEC accounting. + + $ accounting legend code (ALC) + (O) /U.S. Government/ Numeric system used to indicate the minimum + accounting controls required for items of COMSEC material within + the CMCS. [C4009] (See: COMSEC accounting.) + + $ accreditation + (N) An administrative action by which a designated authority + declares that an information system is approved to operate in a + particular security configuration with a prescribed set of + safeguards. [FP102, SP37] (See: certification.) + + Tutorial: An accreditation is usually based on a technical + certification of the system's security mechanisms. To accredit a + system, the approving authority must determine that any residual + risk is an acceptable risk. Although the terms "certification" and + "accreditation" are used more in the U.S. DoD and other U.S. + Government agencies than in commercial organizations, the concepts + apply any place where managers are required to deal with and + accept responsibility for security risks. For example, the + American Bar Association is developing accreditation criteria for + CAs. + + $ accreditation boundary + (O) Synonym for "security perimeter". [C4009] + + + + + + +Shirey Informational [Page 13] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ accreditor + (N) A management official who has been designated to have the + formal authority to "accredit" an information system, i.e., to + authorize the operation of, and the processing of sensitive data + in, the system and to accept the residual risk associated with the + system. (See: accreditation, residual risk.) + + $ ACES + (O) See: Access Certificate for Electronic Services. + + $ ACL + (I) See: access control list. + + $ acquirer + 1. (O) /SET/ "The financial institution that establishes an + account with a merchant and processes payment card authorizations + and payments." [SET1] + + 2. (O) /SET/ "The institution (or its agent) that acquires from + the card acceptor the financial data relating to the transaction + and initiates that data into an interchange system." [SET2] + + $ activation data + (N) Secret data, other than keys, that is required to access a + cryptographic module. (See: CIK. Compare: initialization value.) + + $ active attack + (I) See: secondary definition under "attack". + + $ active content + 1a. (I) Executable software that is bound to a document or other + data file and that executes automatically when a user accesses the + file, without explicit initiation by the user. (Compare: mobile + code.) + + Tutorial: Active content can be mobile code when its associated + file is transferred across a network. + + 1b. (O) "Electronic documents that can carry out or trigger + actions automatically on a computer platform without the + intervention of a user. [This technology enables] mobile code + associated with a document to execute as the document is + rendered." [SP28] + + $ active user + (I) See: secondary definition under "system user". + + + + + +Shirey Informational [Page 14] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ active wiretapping + (I) A wiretapping attack that attempts to alter data being + communicated or otherwise affect data flow. (See: wiretapping. + Compare: active attack, passive wiretapping.) + + $ add-on security + (N) The retrofitting of protection mechanisms, implemented by + hardware or software, in an information system after the system + has become operational. [FP039] (Compare: baked-in security.) + + $ adequate security + (O) /U.S. DoD/ "Security commensurate with the risk and magnitude + of harm resulting from the loss, misuse, or unauthorized access to + or modification of information." (See: acceptable risk, residual + risk.) + + $ administrative security + 1. (I) Management procedures and constraints to prevent + unauthorized access to a system. (See: "third law" under + "Courtney's laws", manager, operational security, procedural + security, security architecture. Compare: technical security.) + + Examples: Clear delineation and separation of duties; + configuration control. + + Usage: Administrative security is usually understood to consist of + methods and mechanisms that are implemented and executed primarily + by people, rather than by automated systems. + + 2. (O) "The management constraints, operational procedures, + accountability procedures, and supplemental controls established + to provide an acceptable level of protection for sensitive data." + [FP039] + + $ administrator + 1. (O) /Common Criteria/ A person that is responsible for + configuring, maintaining, and administering the TOE in a correct + manner for maximum security. (See: administrative security.) + + 2. (O) /ITSEC/ A person in contact with the TOE, who is + responsible for maintaining its operational capability. + + $ Advanced Encryption Standard (AES) + (N) A U.S. Government standard [FP197] (the successor to DES) that + (a) specifies "the AES algorithm", which is a symmetric block + cipher that is based on Rijndael and uses key sizes of 128, 192, + or 256 bits to operate on a 128-bit block, and (b) states policy + for using that algorithm to protect unclassified, sensitive data. + + + +Shirey Informational [Page 15] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Tutorial: Rijndael was designed to handle additional block sizes + and key lengths that were not adopted in the AES. Rijndael was + selected by NIST through a public competition that was held to + find a successor to the DEA; the other finalists were MARS, RC6, + Serpent, and Twofish. + + $ adversary + 1. (I) An entity that attacks a system. (Compare: cracker, + intruder, hacker.) + + 2. (I) An entity that is a threat to a system. + + $ AES + (N) See: Advanced Encryption Standard. + + $ Affirm + (O) A formal methodology, language, and integrated set of software + tools developed at the University of Southern California's + Information Sciences Institute for specifying, coding, and + verifying software to produce correct and reliable programs. + [Cheh] + + $ aggregation + (I) A circumstance in which a collection of information items is + required to be classified at a higher security level than any of + the items is classified individually. (See: classification.) + + $ AH + (I) See: Authentication Header + + $ air gap + (I) An interface between two systems at which (a) they are not + connected physically and (b) any logical connection is not + automated (i.e., data is transferred through the interface only + manually, under human control). (See: sneaker net. Compare: + gateway.) + + Example: Computer A and computer B are on opposite sides of a + room. To move data from A to B, a person carries a disk across the + room. If A and B operate in different security domains, then + moving data across the air gap may involve an upgrade or downgrade + operation. + + $ ALC + (O) See: accounting legend code. + + + + + + +Shirey Informational [Page 16] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ algorithm + (I) A finite set of step-by-step instructions for a problem- + solving or computation procedure, especially one that can be + implemented by a computer. (See: cryptographic algorithm.) + + $ alias + (I) A name that an entity uses in place of its real name, usually + for the purpose of either anonymity or masquerade. + + $ Alice and Bob + (I) The parties that are most often called upon to illustrate the + operation of bipartite security protocols. These and other + dramatis personae are listed by Schneier [Schn]. + + $ American National Standards Institute (ANSI) + (N) A private, not-for-profit association that administers U.S. + private-sector voluntary standards. + + Tutorial: ANSI has approximately 1,000 member organizations, + including equipment users, manufacturers, and others. These + include commercial firms, governmental agencies, and other + institutions and international entities. + + ANSI is the sole U.S. representative to (a) ISO and (b) (via the + U.S. National Committee) the International Electrotechnical + Commission (IEC), which are the two major, non-treaty, + international standards organizations. + + ANSI provides a forum for ANSI-accredited standards development + groups. Among those groups, the following are especially relevant + to Internet security: + - International Committee for Information Technology + Standardization (INCITS) (formerly X3): Primary U.S. focus of + standardization in information and communications technologies, + encompassing storage, processing, transfer, display, + management, organization, and retrieval of information. + Example: [A3092]. + - Accredited Standards Committee X9: Develops, establishes, + maintains, and promotes standards for the financial services + industry. Example: [A9009]. + - Alliance for Telecommunications Industry Solutions (ATIS): + Develops standards, specifications, guidelines, requirements, + technical reports, industry processes, and verification tests + for interoperability and reliability of telecommunications + networks, equipment, and software. Example: [A1523]. + + + + + + +Shirey Informational [Page 17] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ American Standard Code for Information Interchange (ASCII) + (N) A scheme that encodes 128 specified characters -- the numbers + 0-9, the letters a-z and A-Z, some basic punctuation symbols, some + control codes that originated with Teletype machines, and a blank + space -- into the 7-bit binary integers. Forms the basis of the + character set representations used in most computers and many + Internet standards. [FP001] (See: code.) + + $ Anderson report + (O) A 1972 study of computer security that was written by James P. + Anderson for the U.S. Air Force [Ande]. + + Tutorial: Anderson collaborated with a panel of experts to study + Air Force requirements for multilevel security. The study + recommended research and development that was urgently needed to + provide secure information processing for command and control + systems and support systems. The report introduced the reference + monitor concept and provided development impetus for computer and + network security technology. However, many of the security + problems that the 1972 report called "current" still plague + information systems today. + + $ anomaly detection + (I) An intrusion detection method that searches for activity that + is different from the normal behavior of system entities and + system resources. (See: IDS. Compare: misuse detection.) + + $ anonymity + (I) The condition of an identity being unknown or concealed. (See: + alias, anonymizer, anonymous credential, anonymous login, + identity, onion routing, persona certificate. Compare: privacy.) + + Tutorial: An application may require security services that + maintain anonymity of users or other system entities, perhaps to + preserve their privacy or hide them from attack. To hide an + entity's real name, an alias may be used; for example, a financial + institution may assign account numbers. Parties to transactions + can thus remain relatively anonymous, but can also accept the + transactions as legitimate. Real names of the parties cannot be + easily determined by observers of the transactions, but an + authorized third party may be able to map an alias to a real name, + such as by presenting the institution with a court order. In other + applications, anonymous entities may be completely untraceable. + + $ anonymizer + (I) An internetwork service, usually provided via a proxy server, + that provides anonymity and privacy for clients. That is, the + service enables a client to access servers (a) without allowing + + + +Shirey Informational [Page 18] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + anyone to gather information about which servers the client + accesses and (b) without allowing the accessed servers to gather + information about the client, such as its IP address. + + $ anonymous credential + (D) /U.S. Government/ A credential that (a) can be used to + authenticate a person as having a specific attribute or being a + member of a specific group (e.g., military veterans or U.S. + citizens) but (b) does not reveal the individual identity of the + person that presents the credential. [M0404] (See: anonymity.) + + Deprecated Term: IDOCs SHOULD NOT use this term; it mixes concepts + in a potentially misleading way. For example, when the credential + is an X.509 certificate, the term could be misunderstood to mean + that the certificate was signed by a CA that has a persona + certificate. Instead, use "attribute certificate", "organizational + certificate", or "persona certificate" depending on what is meant, + and provide additional explanations as needed. + + $ anonymous login + (I) An access control feature (actually, an access control + vulnerability) in many Internet hosts that enables users to gain + access to general-purpose or public services and resources of a + host (such as allowing any user to transfer data using FTP) + without having a pre-established, identity-specific account (i.e., + user name and password). (See: anonymity.) + + Tutorial: This feature exposes a system to more threats than when + all the users are known, pre-registered entities that are + individually accountable for their actions. A user logs in using a + special, publicly known user name (e.g., "anonymous", "guest", or + "ftp"). To use the public login name, the user is not required to + know a secret password and may not be required to input anything + at all except the name. In other cases, to complete the normal + sequence of steps in a login protocol, the system may require the + user to input a matching, publicly known password (such as + "anonymous") or may ask the user for an e-mail address or some + other arbitrary character string. + + $ ANSI + (N) See: American National Standards Institute. + + $ anti-jam + (N) "Measures ensuring that transmitted information can be + received despite deliberate jamming attempts." [C4009] (See: + electronic security, frequency hopping, jam, spread spectrum.) + + + + + +Shirey Informational [Page 19] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ apex trust anchor + (N) The trust anchor that is superior to all other trust anchors + in a particular system or context. (See: trust anchor, top CA.) + + $ API + (I) See: application programming interface. + + $ APOP + (I) See: POP3 APOP. + + $ Application Layer + See: Internet Protocol Suite, OSIRM. + + $ application program + (I) A computer program that performs a specific function directly + for a user (as opposed to a program that is part of a computer + operating system and exists to perform functions in support of + application programs). + + $ architecture + (I) See: security architecture, system architecture. + + $ archive + 1a. (I) /noun/ A collection of data that is stored for a + relatively long period of time for historical and other purposes, + such as to support audit service, availability service, or system + integrity service. (Compare: backup, repository.) + + 1b. (I) /verb/ To store data in such a way as to create an + archive. (Compare: back up.) + + Tutorial: A digital signature may need to be verified many years + after the signing occurs. The CA -- the one that issued the + certificate containing the public key needed to verify that + signature -- may not stay in operation that long. So every CA + needs to provide for long-term storage of the information needed + to verify the signatures of those to whom it issues certificates. + + $ ARPANET + (I) Advanced Research Projects Agency (ARPA) Network, a pioneer + packet-switched network that (a) was designed, implemented, + operated, and maintained by BBN from January 1969 until July 1975 + under contract to the U.S. Government; (b) led to the development + of today's Internet; and (c) was decommissioned in June 1990. + [B4799, Hafn] + + $ ASCII + (N) See: American Standard Code for Information Interchange. + + + +Shirey Informational [Page 20] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ ASN.1 + (N) See: Abstract Syntax Notation One. + + $ asset + (I) A system resource that is (a) required to be protected by an + information system's security policy, (b) intended to be protected + by a countermeasure, or (c) required for a system's mission. + + $ association + (I) A cooperative relationship between system entities, usually + for the purpose of transferring information between them. (See: + security association.) + + $ assurance See: security assurance. + + $ assurance level + (N) A rank on a hierarchical scale that judges the confidence + someone can have that a TOE adequately fulfills stated security + requirements. (See: assurance, certificate policy, EAL, TCSEC.) + + Example: U.S. Government guidance [M0404] describes four assurance + levels for identity authentication, where each level "describes + the [U.S. Federal Government] agency's degree of certainty that + the user has presented [a credential] that refers to [the user's] + identity." In that guidance, assurance is defined as (a) "the + degree of confidence in the vetting process used to establish the + identity of the individual to whom the credential was issued" and + (b) "the degree of confidence that the individual who uses the + credential is the individual to whom the credential was issued." + + The four levels are described as follows: + - Level 1: Little or no confidence in the asserted identity. + - Level 2: Some confidence in the asserted identity. + - Level 3: High confidence in the asserted identity. + - Level 4: Very high confidence in the asserted identity. + + Standards for determining these levels are provided in a NIST + publication [SP12]. However, as noted there, an assurance level is + "a degree of confidence, not a true measure of how secure the + system actually is. This distinction is necessary because it is + extremely difficult -- and in many cases, virtually impossible -- + to know exactly how secure a system is." + + $ asymmetric cryptography + (I) A modern branch of cryptography (popularly known as "public- + key cryptography") in which the algorithms use a pair of keys (a + public key and a private key) and use a different component of the + pair for each of two counterpart cryptographic operations (e.g., + + + +Shirey Informational [Page 21] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + encryption and decryption, or signature creation and signature + verification). (See: key pair, symmetric cryptography.) + + Tutorial: Asymmetric algorithms have key management advantages + over equivalently strong symmetric ones. First, one key of the + pair need not be known by anyone but its owner; so it can more + easily be kept secret. Second, although the other key is shared by + all entities that use the algorithm, that key need not be kept + secret from other, non-using entities; thus, the key-distribution + part of key management can be done more easily. + + Asymmetric cryptography can be used to create algorithms for + encryption, digital signature, and key agreement: + - In an asymmetric encryption algorithm (e.g., "RSA"), when Alice + wants to ensure confidentiality for data she sends to Bob, she + encrypts the data with a public key provided by Bob. Only Bob + has the matching private key that is needed to decrypt the + data. (Compare: seal.) + - In an asymmetric digital signature algorithm (e.g., "DSA"), + when Alice wants to ensure data integrity or provide + authentication for data she sends to Bob, she uses her private + key to sign the data (i.e., create a digital signature based on + the data). To verify the signature, Bob uses the matching + public key that Alice has provided. + - In an asymmetric key-agreement algorithm (e.g., "Diffie- + Hellman-Merkle"), Alice and Bob each send their own public key + to the other party. Then each uses their own private key and + the other's public key to compute the new key value. + + $ asymmetric key + (I) A cryptographic key that is used in an asymmetric + cryptographic algorithm. (See: asymmetric cryptography, private + key, public key.) + + $ ATIS + (N) See: "Alliance for Telecommunications Industry Solutions" + under "ANSI". + + $ attack + 1. (I) An intentional act by which an entity attempts to evade + security services and violate the security policy of a system. + That is, an actual assault on system security that derives from an + intelligent threat. (See: penetration, violation, vulnerability.) + + 2. (I) A method or technique used in an assault (e.g., + masquerade). (See: blind attack, distributed attack.) + + + + + +Shirey Informational [Page 22] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Tutorial: Attacks can be characterized according to intent: + - An "active attack" attempts to alter system resources or affect + their operation. + - A "passive attack" attempts to learn or make use of information + from a system but does not affect system resources of that + system. (See: wiretapping.) + + The object of a passive attack might be to obtain data that is + needed for an off-line attack. + - An "off-line attack" is one in which the attacker obtains data + from the target system and then analyzes the data on a + different system of the attacker's own choosing, possibly in + preparation for a second stage of attack on the target. + + Attacks can be characterized according to point of initiation: + - An "inside attack" is one that is initiated by an entity inside + the security perimeter (an "insider"), i.e., an entity that is + authorized to access system resources but uses them in a way + not approved by the party that granted the authorization. + - An "outside attack" is initiated from outside the security + perimeter, by an unauthorized or illegitimate user of the + system (an "outsider"). In the Internet, potential outside + attackers range from amateur pranksters to organized criminals, + international terrorists, and hostile governments. + Attacks can be characterized according to method of delivery: + - In a "direct attack", the attacker addresses attacking packets + to the intended victim(s). + - In an "indirect attack", the attacker addresses packets to a + third party, and the packets either have the address(es) of the + intended victim(s) as their source address(es) or indicate the + intended victim(s) in some other way. The third party responds + by sending one or more attacking packets to the intended + victims. The attacker can use third parties as attack + amplifiers by providing a broadcast address as the victim + address (e.g., "smurf attack"). (See: reflector attack. + Compare: reflection attack, replay attack.) + + + + + + + + + + + + + + + +Shirey Informational [Page 23] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + The term "attack" relates to some other basic security terms as + shown in the following diagram: + + + - - - - - - - - - - - - + + - - - - + + - - - - - - - - - - -+ + | An Attack: | |Counter- | | A System Resource: | + | i.e., A Threat Action | | measure | | Target of the Attack | + | +----------+ | | | | +-----------------+ | + | | Attacker |<==================||<========= | | + | | i.e., | Passive | | | | | Vulnerability | | + | | A Threat |<=================>||<========> | | + | | Agent | or Active | | | | +-------|||-------+ | + | +----------+ Attack | | | | VVV | + | | | | | Threat Consequences | + + - - - - - - - - - - - - + + - - - - + + - - - - - - - - - - -+ + + $ attack potential + (I) The perceived likelihood of success should an attack be + launched, expressed in terms of the attacker's ability (i.e., + expertise and resources) and motivation. (Compare: threat, risk.) + + $ attack sensing, warning, and response + (I) A set of security services that cooperate with audit service + to detect and react to indications of threat actions, including + both inside and outside attacks. (See: indicator.) + + $ attack tree + (I) A branching, hierarchical data structure that represents a set + of potential approaches to achieving an event in which system + security is penetrated or compromised in a specified way. [Moor] + + Tutorial: Attack trees are special cases of fault trees. The + security incident that is the goal of the attack is represented as + the root node of the tree, and the ways that an attacker could + reach that goal are iteratively and incrementally represented as + branches and subnodes of the tree. Each subnode defines a subgoal, + and each subgoal may have its own set of further subgoals, etc. + The final nodes on the paths outward from the root, i.e., the leaf + nodes, represent different ways to initiate an attack. Each node + other than a leaf is either an AND-node or an OR-node. To achieve + the goal represented by an AND-node, the subgoals represented by + all of that node's subnodes must be achieved; and for an OR-node, + at least one of the subgoals must be achieved. Branches can be + labeled with values representing difficulty, cost, or other attack + attributes, so that alternative attacks can be compared. + + + + + + + +Shirey Informational [Page 24] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ attribute + (N) Information of a particular type concerning an identifiable + system entity or object. An "attribute type" is the component of + an attribute that indicates the class of information given by the + attribute; and an "attribute value" is a particular instance of + the class of information indicated by an attribute type. (See: + attribute certificate.) + + $ attribute authority (AA) + 1. (N) A CA that issues attribute certificates. + + 2. (O) "An authority [that] assigns privileges by issuing + attribute certificates." [X509] + + Deprecated Usage: The abbreviation "AA" SHOULD NOT be used in an + IDOC unless it is first defined in the IDOC. + + $ attribute certificate + 1. (I) A digital certificate that binds a set of descriptive data + items, other than a public key, either directly to a subject name + or to the identifier of another certificate that is a public-key + certificate. (See: capability token.) + + 2. (O) "A data structure, digitally signed by an [a]ttribute + [a]uthority, that binds some attribute values with identification + information about its holder." [X509] + + Tutorial: A public-key certificate binds a subject name to a + public key value, along with information needed to perform certain + cryptographic functions using that key. Other attributes of a + subject, such as a security clearance, may be certified in a + separate kind of digital certificate, called an attribute + certificate. A subject may have multiple attribute certificates + associated with its name or with each of its public-key + certificates. + + An attribute certificate might be issued to a subject in the + following situations: + - Different lifetimes: When the lifetime of an attribute binding + is shorter than that of the related public-key certificate, or + when it is desirable not to need to revoke a subject's public + key just to revoke an attribute. + - Different authorities: When the authority responsible for the + attributes is different than the one that issues the public-key + certificate for the subject. (There is no requirement that an + attribute certificate be issued by the same CA that issued the + associated public-key certificate.) + + + + +Shirey Informational [Page 25] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ audit + See: security audit. + + $ audit log + (I) Synonym for "security audit trail". + + $ audit service + (I) A security service that records information needed to + establish accountability for system events and for the actions of + system entities that cause them. (See: security audit.) + + $ audit trail + (I) See: security audit trail. + + $ AUTH + (I) See: POP3 AUTH. + + $ authenticate + (I) Verify (i.e., establish the truth of) an attribute value + claimed by or for a system entity or system resource. (See: + authentication, validate vs. verify, "relationship between data + integrity service and authentication services" under "data + integrity service".) + + Deprecated Usage: In general English usage, this term is used with + the meaning "to prove genuine" (e.g., an art expert authenticates + a Michelangelo painting); but IDOCs should restrict usage as + follows: + - IDOCs SHOULD NOT use this term to refer to proving or checking + that data has not been changed, destroyed, or lost in an + unauthorized or accidental manner. Instead, use "verify". + - IDOCs SHOULD NOT use this term to refer to proving the truth or + accuracy of a fact or value such as a digital signature. + Instead, use "verify". + - IDOCs SHOULD NOT use this term to refer to establishing the + soundness or correctness of a construct, such as a digital + certificate. Instead, use "validate". + + $ authentication + (I) The process of verifying a claim that a system entity or + system resource has a certain attribute value. (See: attribute, + authenticate, authentication exchange, authentication information, + credential, data origin authentication, peer entity + authentication, "relationship between data integrity service and + authentication services" under "data integrity service", simple + authentication, strong authentication, verification, X.509.) + + + + + +Shirey Informational [Page 26] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Tutorial: Security services frequently depend on authentication of + the identity of users, but authentication may involve any type of + attribute that is recognized by a system. A claim may be made by a + subject about itself (e.g., at login, a user typically asserts its + identity) or a claim may be made on behalf of a subject or object + by some other system entity (e.g., a user may claim that a data + object originates from a specific source, or that a data object is + classified at a specific security level). + + An authentication process consists of two basic steps: + - Identification step: Presenting the claimed attribute value + (e.g., a user identifier) to the authentication subsystem. + - Verification step: Presenting or generating authentication + information (e.g., a value signed with a private key) that acts + as evidence to prove the binding between the attribute and that + for which it is claimed. (See: verification.) + + $ authentication code + (D) Synonym for a checksum based on cryptography. (Compare: Data + Authentication Code, Message Authentication Code.) + + Deprecated Term: IDOCs SHOULD NOT use this uncapitalized term as a + synonym for any kind of checksum, regardless of whether or not the + checksum is cryptographic. Instead, use "checksum", "Data + Authentication Code", "error detection code", "hash", "keyed + hash", "Message Authentication Code", "protected checksum", or + some other recommended term, depending on what is meant. + + The term mixes concepts in a potentially misleading way. The word + "authentication" is misleading because the checksum may be used to + perform a data integrity function rather than a data origin + authentication function. + + $ authentication exchange + 1. (I) A mechanism to verify the identity of an entity by means of + information exchange. + + 2. (O) "A mechanism intended to ensure the identity of an entity + by means of information exchange." [I7498-2] + + $ Authentication Header (AH) + (I) An Internet protocol [R2402, R4302] designed to provide + connectionless data integrity service and connectionless data + origin authentication service for IP datagrams, and (optionally) + to provide partial sequence integrity and protection against + replay attacks. (See: IPsec. Compare: ESP.) + + + + + +Shirey Informational [Page 27] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Tutorial: Replay protection may be selected by the receiver when a + security association is established. AH authenticates the upper- + layer PDU that is carried as an IP SDU, and also authenticates as + much of the IP PCI (i.e., the IP header) as possible. However, + some IP header fields may change in transit, and the value of + these fields, when the packet arrives at the receiver, may not be + predictable by the sender. Thus, the values of such fields cannot + be protected end-to-end by AH; protection of the IP header by AH + is only partial when such fields are present. + + AH may be used alone, or in combination with the ESP, or in a + nested fashion with tunneling. Security services can be provided + between a pair of communicating hosts, between a pair of + communicating security gateways, or between a host and a gateway. + ESP can provide nearly the same security services as AH, and ESP + can also provide data confidentiality service. The main difference + between authentication services provided by ESP and AH is the + extent of the coverage; ESP does not protect IP header fields + unless they are encapsulated by AH. + + $ authentication information + (I) Information used to verify an identity claimed by or for an + entity. (See: authentication, credential, user. Compare: + identification information.) + + Tutorial: Authentication information may exist as, or be derived + from, one of the following: (a) Something the entity knows (see: + password); (b) something the entity possesses (see: token); (c) + something the entity is (see: biometric authentication). + + $ authentication service + (I) A security service that verifies an identity claimed by or for + an entity. (See: authentication.) + + Tutorial: In a network, there are two general forms of + authentication service: data origin authentication service and + peer entity authentication service. + + $ authenticity + (I) The property of being genuine and able to be verified and be + trusted. (See: authenticate, authentication, validate vs. verify.) + + $ authority + (D) /PKI/ "An entity [that is] responsible for the issuance of + certificates." [X509] + + + + + + +Shirey Informational [Page 28] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Deprecated Usage: IDOCs SHOULD NOT use this term as a synonym for + attribute authority, certification authority, registration + authority, or similar terms; the shortened form may cause + confusion. Instead, use the full term at the first instance of + usage and then, if it is necessary to shorten text, use AA, CA, + RA, and other abbreviations defined in this Glossary. + + $ authority certificate + (D) "A certificate issued to an authority (e.g. either to a + certification authority or to an attribute authority)." [X509] + (See: authority.) + + Deprecated Term: IDOCs SHOULD NOT use this term because it is + ambiguous. Instead, use the full term "certification authority + certificate", "attribute authority certificate", "registration + authority certificate", etc. at the first instance of usage and + then, if it is necessary to shorten text, use AA, CA, RA, and + other abbreviations defined in this Glossary. + + $ Authority Information Access extension + (I) The private extension defined by PKIX for X.509 certificates + to indicate "how to access CA information and services for the + issuer of the certificate in which the extension appears. + Information and services may include on-line validation services + and CA policy data." [R3280] (See: private extension.) + + $ authorization + 1a. (I) An approval that is granted to a system entity to access a + system resource. (Compare: permission, privilege.) + + Usage: Some synonyms are "permission" and "privilege". Specific + terms are preferred in certain contexts: + - /PKI/ "Authorization" SHOULD be used, to align with + "certification authority" in the standard [X509]. + - /role-based access control/ "Permission" SHOULD be used, to + align with the standard [ANSI]. + - /computer operating systems/ "Privilege" SHOULD be used, to + align with the literature. (See: privileged process, privileged + user.) + + Tutorial: The semantics and granularity of authorizations depend + on the application and implementation (see: "first law" under + "Courtney's laws"). An authorization may specify a particular + access mode -- such as read, write, or execute -- for one or more + system resources. + + 1b. (I) A process for granting approval to a system entity to + access a system resource. + + + +Shirey Informational [Page 29] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + 2. (O) /SET/ "The process by which a properly appointed person or + persons grants permission to perform some action on behalf of an + organization. This process assesses transaction risk, confirms + that a given transaction does not raise the account holder's debt + above the account's credit limit, and reserves the specified + amount of credit. (When a merchant obtains authorization, payment + for the authorized amount is guaranteed -- provided, of course, + that the merchant followed the rules associated with the + authorization process.)" [SET2] + + $ authorization credential + (I) See: /access control/ under "credential". + + $ authorize + (I) Grant an authorization to a system entity. + + $ authorized user + (I) /access control/ A system entity that accesses a system + resource for which the entity has received an authorization. + (Compare: insider, outsider, unauthorized user.) + + Deprecated Usage: IDOCs that use this term SHOULD state a + definition for it because the term is used in many ways and could + easily be misunderstood. + + $ automated information system + See: information system. + + $ availability + 1. (I) The property of a system or a system resource being + accessible, or usable or operational upon demand, by an authorized + system entity, according to performance specifications for the + system; i.e., a system is available if it provides services + according to the system design whenever users request them. (See: + critical, denial of service. Compare: precedence, reliability, + survivability.) + + 2. (O) "The property of being accessible and usable upon demand by + an authorized entity." [I7498-2] + + 3. (D) "Timely, reliable access to data and information services + for authorized users." [C4009] + + Deprecated Definition: IDOCs SHOULD NOT use the term with + definition 3; the definition mixes "availability" with + "reliability", which is a different property. (See: reliability.) + + + + + +Shirey Informational [Page 30] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Tutorial: Availability requirements can be specified by + quantitative metrics, but sometimes are stated qualitatively, such + as in the following: + - "Flexible tolerance for delay" may mean that brief system + outages do not endanger mission accomplishment, but extended + outages may endanger the mission. + - "Minimum tolerance for delay" may mean that mission + accomplishment requires the system to provide requested + services in a short time. + + $ availability service + (I) A security service that protects a system to ensure its + availability. + + Tutorial: This service addresses the security concerns raised by + denial-of-service attacks. It depends on proper management and + control of system resources, and thus depends on access control + service and other security services. + + $ avoidance + (I) See: secondary definition under "security". + + $ B1, B2, or B3 computer system + (O) /TCSEC/ See: Tutorial under "Trusted Computer System + Evaluation Criteria". + + $ back door + 1. (I) /COMPUSEC/ A computer system feature -- which may be (a) an + unintentional flaw, (b) a mechanism deliberately installed by the + system's creator, or (c) a mechanism surreptitiously installed by + an intruder -- that provides access to a system resource by other + than the usual procedure and usually is hidden or otherwise not + well-known. (See: maintenance hook. Compare: Trojan Horse.) + + Example: A way to access a computer other than through a normal + login. Such an access path is not necessarily designed with + malicious intent; operating systems sometimes are shipped by the + manufacturer with hidden accounts intended for use by field + service technicians or the vendor's maintenance programmers. + + 2. (I) /cryptography/ A feature of a cryptographic system that + makes it easily possible to break or circumvent the protection + that the system is designed to provide. + + Example: A feature that makes it possible to decrypt cipher text + much more quickly than by brute-force cryptanalysis, without + having prior knowledge of the decryption key. + + + + +Shirey Informational [Page 31] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ back up + (I) /verb/ Create a reserve copy of data or, more generally, + provide alternate means to perform system functions despite loss + of system resources. (See: contingency plan. Compare: archive.) + + $ backup + (I) /noun or adjective/ Refers to alternate means of performing + system functions despite loss of system resources. (See: + contingency plan). + + Example: A reserve copy of data, preferably one that is stored + separately from the original, for use if the original becomes lost + or damaged. (Compare: archive.) + + $ bagbiter + (D) /slang/ "An entity, such as a program or a computer, that + fails to work or that works in a remarkably clumsy manner. A + person who has caused some trouble, inadvertently or otherwise, + typically by failing to program the computer properly." [NCSSG] + (See: flaw.) + + Deprecated Term: It is likely that other cultures use different + metaphors for these concepts. Therefore, to avoid international + misunderstanding, IDOCs SHOULD NOT use this term. (See: Deprecated + Usage under "Green Book".) + + $ baggage + (O) /SET/ An "opaque encrypted tuple, which is included in a SET + message but appended as external data to the PKCS encapsulated + data. This avoids superencryption of the previously encrypted + tuple, but guarantees linkage with the PKCS portion of the + message." [SET2] + + Deprecated Usage: IDOCs SHOULD NOT use this term to describe a + data element, except in the form "SET(trademark) baggage" with the + meaning given above. + + $ baked-in security + (D) The inclusion of security mechanisms in an information system + beginning at an early point in the system's lifecycle, i.e., + during the design phase, or at least early in the implementation + phase. (Compare: add-on security.) + + Deprecated Term: It is likely that other cultures use different + metaphors for this concept. Therefore, to avoid international + misunderstanding, IDOCs SHOULD NOT use this term (unless they also + provide a definition like this one). (See: Deprecated Usage under + "Green Book".) + + + +Shirey Informational [Page 32] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ bandwidth + (I) The total width of the frequency band that is available to or + used by a communication channel; usually expressed in Hertz (Hz). + (RFC 3753) (Compare: channel capacity.) + + $ bank identification number (BIN) + 1. (O) The digits of a credit card number that identify the + issuing bank. (See: primary account number.) + + 2. (O) /SET/ The first six digits of a primary account number. + + $ Basic Encoding Rules (BER) + (I) A standard for representing ASN.1 data types as strings of + octets. [X690] (See: Distinguished Encoding Rules.) + + Deprecated Usage: Sometimes incorrectly treated as part of ASN.1. + However, ASN.1 properly refers only to a syntax description + language, and not to the encoding rules for the language. + + $ Basic Security Option + (I) See: secondary definition under "IPSO". + + $ bastion host + (I) A strongly protected computer that is in a network protected + by a firewall (or is part of a firewall) and is the only host (or + one of only a few) in the network that can be directly accessed + from networks on the other side of the firewall. (See: firewall.) + + Tutorial: Filtering routers in a firewall typically restrict + traffic from the outside network to reaching just one host, the + bastion host, which usually is part of the firewall. Since only + this one host can be directly attacked, only this one host needs + to be very strongly protected, so security can be maintained more + easily and less expensively. However, to allow legitimate internal + and external users to access application resources through the + firewall, higher-layer protocols and services need to be relayed + and forwarded by the bastion host. Some services (e.g., DNS and + SMTP) have forwarding built in; other services (e.g., TELNET and + FTP) require a proxy server on the bastion host. + + $ BBN Technologies Corp. (BBN) + (O) The research-and-development company (originally called Bolt + Baranek and Newman, Inc.) that built the ARPANET. + + $ BCA + (O) See: brand certification authority. + + + + + +Shirey Informational [Page 33] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ BCR + (O) See: BLACK/Crypto/RED. + + $ BCI + (O) See: brand CRL identifier. + + $ Bell-LaPadula model + (N) A formal, mathematical, state-transition model of + confidentiality policy for multilevel-secure computer systems + [Bell]. (Compare: Biba model, Brewer-Nash model.) + + Tutorial: The model, devised by David Bell and Leonard LaPadula at + The MITRE Corporation in 1973, characterizes computer system + elements as subjects and objects. To determine whether or not a + subject is authorized for a particular access mode on an object, + the clearance of the subject is compared to the classification of + the object. The model defines the notion of a "secure state", in + which the only permitted access modes of subjects to objects are + in accordance with a specified security policy. It is proven that + each state transition preserves security by moving from secure + state to secure state, thereby proving that the system is secure. + In this model, a multilevel-secure system satisfies several rules, + including the "confinement property" (a.k.a. the "*-property"), + the "simple security property", and the "tranquility property". + + $ benign + 1. (N) /COMSEC/ "Condition of cryptographic data [such] that [the + data] cannot be compromised by human access [to the data]." + [C4009] + + 2. (O) /COMPUSEC/ See: secondary definition under "trust". + + $ benign fill + (N) Process by which keying material is generated, distributed, + and placed into an ECU without exposure to any human or other + system entity, except the cryptographic module that consumes and + uses the material. (See: benign.) + + $ BER + (I) See: Basic Encoding Rules. + + $ beyond A1 + 1. (O) /formal/ A level of security assurance that is beyond the + highest level (level A1) of criteria specified by the TCSEC. (See: + Tutorial under "Trusted Computer System Evaluation Criteria".) + + + + + + +Shirey Informational [Page 34] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + 2. (O) /informal/ A level of trust so high that it is beyond + state-of-the-art technology; i.e., it cannot be provided or + verified by currently available assurance methods, and especially + not by currently available formal methods. + + $ Biba integrity + (N) Synonym for "source integrity". + + $ Biba model + (N) A formal, mathematical, state-transition model of integrity + policy for multilevel-secure computer systems [Biba]. (See: source + integrity. Compare: Bell-LaPadula model.) + + Tutorial: This model for integrity control is analogous to the + Bell-LaPadula model for confidentiality control. Each subject and + object is assigned an integrity level and, to determine whether or + not a subject is authorized for a particular access mode on an + object, the integrity level of the subject is compared to that of + the object. The model prohibits the changing of information in an + object by a subject with a lesser or incomparable level. The rules + of the Biba model are duals of the corresponding rules in the + Bell-LaPadula model. + + $ billet + (N) "A personnel position or assignment that may be filled by one + person." [JCP1] (Compare: principal, role, user.) + + Tutorial: In an organization, a "billet" is a populational + position, of which there is exactly one instance; but a "role" is + functional position, of which there can be multiple instances. + System entities are in one-to-one relationships with their + billets, but may be in many-to-one and one-to-many relationships + with their roles. + + $ BIN + (O) See: bank identification number. + + $ bind + (I) To inseparably associate by applying some security mechanism. + + Example: A CA creates a public-key certificate by using a digital + signature to bind together (a) a subject name, (b) a public key, + and usually (c) some additional data items (e.g., "X.509 public- + key certificate"). + + $ biometric authentication + (I) A method of generating authentication information for a person + by digitizing measurements of a physical or behavioral + + + +Shirey Informational [Page 35] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + characteristic, such as a fingerprint, hand shape, retina pattern, + voiceprint, handwriting style, or face. + + $ birthday attack + (I) A class of attacks against cryptographic functions, including + both encryption functions and hash functions. The attacks take + advantage of a statistical property: Given a cryptographic + function having an N-bit output, the probability is greater than + 1/2 that for 2**(N/2) randomly chosen inputs, the function will + produce at least two outputs that are identical. (See: Tutorial + under "hash function".) + + Derivation: From the somewhat surprising fact (often called the + "birthday paradox") that although there are 365 days in a year, + the probability is greater than 1/2 that two of more people share + the same birthday in any randomly chosen group of 23 people. + + Birthday attacks enable an adversary to find two inputs for which + a cryptographic function produces the same cipher text (or find + two inputs for which a hash functions produces the same hash + result) much faster than a brute-force attack can; and a clever + adversary can use such a capability to create considerable + mischief. However, no birthday attack can enable an adversary to + decrypt a given cipher text (or find a hash input that results in + a given hash result) any faster than a brute-force attack can. + + $ bit + (I) A contraction of the term "binary digit"; the smallest unit of + information storage, which has two possible states or values. The + values usually are represented by the symbols "0" (zero) and "1" + (one). (See: block, byte, nibble, word.) + + $ bit string + (I) A sequence of bits, each of which is either "0" or "1". + + $ BLACK + 1. (N) Designation for data that consists only of cipher text, and + for information system equipment items or facilities that handle + only cipher text. Example: "BLACK key". (See: BCR, color change, + RED/BLACK separation. Compare: RED.) + + 2. (O) /U.S. Government/ "Designation applied to information + systems, and to associated areas, circuits, components, and + equipment, in which national security information is encrypted or + is not processed." [C4009] + + 3. (D) Any data that can be disclosed without harm. + + + + +Shirey Informational [Page 36] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Deprecated Definition: IDOCs SHOULD NOT use the term with + definition 3 because the definition is ambiguous with regard to + whether or not the data is protected. + + $ BLACK/Crypto/RED (BCR) + (N) An experimental, end-to-end, network packet encryption system + developed in a working prototype form by BBN and the Collins Radio + division of Rockwell Corporation in the 1975-1980 time frame for + the U.S. DoD. BCR was the first network security system to support + TCP/IP traffic, and it incorporated the first DES chips that were + validated by the U.S. National Bureau of Standards (now called + NIST). BCR also was the first to use a KDC and an ACC to manage + connections. + + $ BLACK key + (N) A key that is protected with a key-encrypting key and that + must be decrypted before use. (See: BLACK. Compare: RED key.) + + $ BLACKER + (O) An end-to-end encryption system for computer data networks + that was developed by the U.S. DoD in the 1980s to provide host- + to-host data confidentiality service for datagrams at OSIRM Layer + 3. [Weis] (Compare: CANEWARE, IPsec.) + + Tutorial: Each user host connects to its own bump-in-the-wire + encryption device called a BLACKER Front End (BFE, TSEC/KI-111), + through which the host connects to the subnetwork. The system also + includes two types of centralized devices: one or more KDCs + connect to the subnetwork and communicate with assigned sets of + BFEs, and one or more ACCs connect to the subnetwork and + communicate with assigned KDCs. BLACKER uses only symmetric + encryption. A KDC distributes session keys to BFE pairs as + authorized by an ACC. Each ACC maintains a database for a set of + BFEs, and the database determines which pairs from that set (i.e., + which pairs of user hosts behind the BFEs) are authorized to + communicate and at what security levels. + + The BLACKER system is MLS in three ways: (a) The BFEs form a + security perimeter around a subnetwork, separating user hosts from + the subnetwork, so that the subnetwork can operate at a different + security level (possibly a lower, less expensive level) than the + hosts. (b) The BLACKER components are trusted to separate + datagrams of different security levels, so that each datagram of a + given security level can be received only by a host that is + authorized for that security level; and thus BLACKER can separate + host communities that operate at different security levels. (c) + The host side of a BFE is itself MLS and can recognize a security + label on each packet, so that an MLS user host can be authorized + + + +Shirey Informational [Page 37] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + to successively transmit datagrams that are labeled with different + security levels. + + $ blind attack + (I) A type of network-based attack method that does not require + the attacking entity to receive data traffic from the attacked + entity; i.e., the attacker does not need to "see" data packets + sent by the victim. Example: SYN flood. + + Tutorial: If an attack method is blind, the attacker's packets can + carry (a) a false IP source address (making it difficult for the + victim to find the attacker) and (b) a different address on every + packet (making it difficult for the victim to block the attack). + If the attacker needs to receive traffic from the victim, the + attacker must either (c) reveal its own IP address to the victim + (which enables the victim to find the attacker or block the attack + by filtering) or (d) provide a false address and also subvert + network routing mechanisms to divert the returning packets to the + attacker (which makes the attack more complex, more difficult, or + more expensive). [R3552] + + $ block + (I) A bit string or bit vector of finite length. (See: bit, block + cipher. Compare: byte, word.) + + Usage: An "N-bit block" contains N bits, which usually are + numbered from left to right as 1, 2, 3, ..., N. + + $ block cipher + (I) An encryption algorithm that breaks plain text into fixed-size + segments and uses the same key to transform each plaintext segment + into a fixed-size segment of cipher text. Examples: AES, Blowfish, + DEA, IDEA, RC2, and SKIPJACK. (See: block, mode. Compare: stream + cipher.) + + Tutorial: A block cipher can be adapted to have a different + external interface, such as that of a stream cipher, by using a + mode of cryptographic operation to package the basic algorithm. + (See: CBC, CCM, CFB, CMAC, CTR, DEA, ECB, OFB.) + + $ Blowfish + (N) A symmetric block cipher with variable-length key (32 to 448 + bits) designed in 1993 by Bruce Schneier as an unpatented, + license-free, royalty-free replacement for DES or IDEA. [Schn] + (See: Twofish.) + + + + + + +Shirey Informational [Page 38] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ brain-damaged + (D) /slang/ "Obviously wrong: extremely poorly designed. Calling + something brain-damaged is very extreme. The word implies that the + thing is completely unusable, and that its failure to work is due + to poor design, not accident." [NCSSG] (See: flaw.) + + Deprecated Term: It is likely that other cultures use different + metaphors for this concept. Therefore, to avoid international + misunderstanding, IDOCs SHOULD NOT use this term. (See: Deprecated + Usage under "Green Book".) + + $ brand + 1. (I) A distinctive mark or name that identifies a product or + business entity. + + 2. (O) /SET/ The name of a payment card. (See: BCA.) + + Tutorial: Financial institutions and other companies have founded + payment card brands, protect and advertise the brands, establish + and enforce rules for use and acceptance of their payment cards, + and provide networks to interconnect the financial institutions. + These brands combine the roles of issuer and acquirer in + interactions with cardholders and merchants. [SET1] + + $ brand certification authority (BCA) + (O) /SET/ A CA owned by a payment card brand, such as MasterCard, + Visa, or American Express. [SET2] (See: certification hierarchy, + SET.) + + $ brand CRL identifier (BCI) + (O) /SET/ A digitally signed list, issued by a BCA, of the names + of CAs for which CRLs need to be processed when verifying + signatures in SET messages. [SET2] + + $ break + (I) /cryptography/ To successfully perform cryptanalysis and thus + succeed in decrypting data or performing some other cryptographic + function, without initially having knowledge of the key that the + function requires. (See: penetrate, strength, work factor.) + + Usage: This term applies to encrypted data or, more generally, to + a cryptographic algorithm or cryptographic system. Also, while the + most common use is to refer to completely breaking an algorithm, + the term is also used when a method is found that substantially + reduces the work factor. + + + + + + +Shirey Informational [Page 39] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ Brewer-Nash model + (N) A security model [BN89] to enforce the Chinese wall policy. + (Compare: Bell-LaPadula model, Clark-Wilson model.) + + Tutorial: All proprietary information in the set of commercial + firms F(1), F(2), ..., F(N) is categorized into mutually exclusive + conflict-of-interest classes I(1), I(2), ..., I(M) that apply + across all firms. Each firm belongs to exactly one class. The + Brewer-Nash model has the following mandatory rules: + - Brewer-Nash Read Rule: Subject S can read information object O + from firm F(i) only if either (a) O is from the same firm as + some object previously read by S *or* (b) O belongs to a class + I(i) from which S has not previously read any object. (See: + object, subject.) + - Brewer-Nash Write Rule: Subject S can write information object + O to firm F(i) only if (a) S can read O by the Brewer-Nash Read + Rule *and* (b) no object can be read by S from a different firm + F(j), no matter whether F(j) belongs to the same class as F(i) + or to a different class. + + $ bridge + (I) A gateway for traffic flowing at OSIRM Layer 2 between two + networks (usually two LANs). (Compare: bridge CA, router.) + + $ bridge CA + (I) A PKI consisting of only a CA that cross-certifies with CAs of + some other PKIs. (See: cross-certification. Compare: bridge.) + + Tutorial: A bridge CA functions as a hub that enables a + certificate user in any of the PKIs that attach to the bridge, to + validate certificates issued in the other attached PKIs. + + For example, a bridge CA (BCA) CA1 + could cross-certify with four ^ + PKIs that have the roots CA1, | + CA2, CA3, and CA4. The cross- v + certificates that the roots CA2 <-> BCA <-> CA3 + exchange with the BCA enable an ^ + end entity EE1 certified under | + under CA1 in PK1 to construct v + a certification path needed to CA4 + validate the certificate of + end entity EE2 under CA2, CA1 -> BCA -> CA2 -> EE2 + or vice versa. CA2 -> BCA -> CA1 -> EE1 + + + + + + + +Shirey Informational [Page 40] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ British Standard 7799 + (N) Part 1 of the standard is a code of practice for how to secure + an information system. Part 2 specifies the management framework, + objectives, and control requirements for information security + management systems. [BS7799] (See: ISO 17799.) + + $ browser + (I) A client computer program that can retrieve and display + information from servers on the World Wide Web. Examples: Netscape + Navigator and Microsoft Internet Explorer. + + $ brute force + (I) A cryptanalysis technique or other kind of attack method + involving an exhaustive procedure that tries a large number of + possible solutions to the problem. (See: impossible, strength, + work factor.) + + Tutorial: In some cases, brute force involves trying all of the + possibilities. For example, for cipher text where the analyst + already knows the decryption algorithm, a brute-force technique + for finding matching plain text is to decrypt the message with + every possible key. In other cases, brute force involves trying a + large number of possibilities but substantially fewer than all of + them. For example, given a hash function that produces an N-bit + hash result, the probability is greater than 1/2 that the analyst + will find two inputs that have the same hash result after trying + only 2**(N/2) randomly chosen inputs. (See: birthday attack.) + + $ BS7799 + (N) See: British Standard 7799. + + $ buffer overflow + (I) Any attack technique that exploits a vulnerability resulting + from computer software or hardware that does not check for + exceeding the bounds of a storage area when data is written into a + sequence of storage locations beginning in that area. + + Tutorial: By causing a normal system operation to write data + beyond the bounds of a storage area, the attacker seeks to either + disrupt system operation or cause the system to execute malicious + software inserted by the attacker. + + $ buffer zone + (I) A neutral internetwork segment used to connect other segments + that each operate under a different security policy. + + + + + + +Shirey Informational [Page 41] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Tutorial: To connect a private network to the Internet or some + other relatively public network, one could construct a small, + separate, isolated LAN and connect it to both the private network + and the public network; one or both of the connections would + implement a firewall to limit the traffic that could pass through + the buffer zone. + + $ bulk encryption + 1. (I) Encryption of multiple channels by aggregating them into a + single transfer path and then encrypting that path. (See: + channel.) + + 2. (O) "Simultaneous encryption of all channels of a multichannel + telecommunications link." [C4009] (Compare: bulk keying material.) + + Usage: The use of "simultaneous" in definition 2 could be + interpreted to mean that multiple channels are encrypted + separately but at the same time. However, the common meaning of + the term is that multiple data flows are combined into a single + stream and then that stream is encrypted as a whole. + + $ bulk key + (D) In a few published descriptions of hybrid encryption for SSH, + Windows 2000, and other applications, this term refers to a + symmetric key that (a) is used to encrypt a relatively large + amount of data and (b) is itself encrypted with a public key. + (Compare: bulk keying material, session key.) + + Example: To send a large file to Bob, Alice (a) generates a + symmetric key and uses it to encrypt the file (i.e., encrypt the + bulk of the information that is to be sent) and then (b) encrypts + that symmetric key (the "bulk key") with Bob's public key. + + Deprecated Term: IDOCs SHOULD NOT use this term or definition; the + term is not well-established and could be confused with the + established term "bulk keying material". Instead, use "symmetric + key" and carefully explain how the key is applied. + + $ bulk keying material + (N) Refers to handling keying material in large quantities, e.g., + as a dataset that contains many items of keying material. (See: + type 0. Compare: bulk key, bulk encryption.) + + $ bump-in-the-stack + (I) An implementation approach that places a network security + mechanism inside the system that is to be protected. (Compare: + bump-in-the-wire.) + + + + +Shirey Informational [Page 42] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Example: IPsec can be implemented inboard, in the protocol stack + of an existing system or existing system design, by placing a new + layer between the existing IP layer and the OSIRM Layer 3 drivers. + Source code access for the existing stack is not required, but the + system that contains the stack does need to be modified [R4301]. + + $ bump-in-the-wire + (I) An implementation approach that places a network security + mechanism outside of the system that is to be protected. (Compare: + bump-in-the-stack.) + + Example: IPsec can be implemented outboard, in a physically + separate device, so that the system that receives the IPsec + protection does not need to be modified at all [R4301]. Military- + grade link encryption has mainly been implemented as bump-in-the- + wire devices. + + $ business-case analysis + (N) An extended form of cost-benefit analysis that considers + factors beyond financial metrics, including security factors such + as the requirement for security services, their technical and + programmatic feasibility, their qualitative benefits, and + associated risks. (See: risk analysis.) + + $ byte + (I) A fundamental unit of computer storage; the smallest + addressable unit in a computer's architecture. Usually holds one + character of information and, today, usually means eight bits. + (Compare: octet.) + + Usage: Understood to be larger than a "bit", but smaller than a + "word". Although "byte" almost always means "octet" today, some + computer architectures have had bytes in other sizes (e.g., six + bits, nine bits). Therefore, an STD SHOULD state the number of + bits in a byte where the term is first used in the STD. + + $ C field + (D) See: Compartments field. + + $ C1 or C2 computer system + (O) /TCSEC/ See: Tutorial under "Trusted Computer System + Evaluation Criteria". + + $ CA + (I) See: certification authority. + + + + + + +Shirey Informational [Page 43] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ CA certificate + (D) "A [digital] certificate for one CA issued by another CA." + [X509] + + Deprecated Definition: IDOCs SHOULD NOT use the term with this + definition; the definition is ambiguous with regard to how the + certificate is constructed and how it is intended to be used. + IDOCs that use this term SHOULD provide a technical definition for + it. (See: certificate profile.) + + Tutorial: There is no single, obvious choice for a technical + definition of this term. Different PKIs can use different + certificate profiles, and X.509 provides several choices of how to + issue certificates to CAs. For example, one possible definition is + the following: A v3 X.509 public-key certificate that has a + "basicConstraints" extension containing a "cA" value of "TRUE". + That would specifically indicate that "the certified public key + may be used to verify certificate signatures", i.e., that the + private key may be used by a CA. + + However, there also are other ways to indicate such usage. The + certificate may have a "key Usage" extension that indicates the + purposes for which the public key may be used, and one of the + values that X.509 defines for that extension is "keyCertSign", to + indicate that the certificate may be used for verifying a CA's + signature on certificates. If "keyCertSign" is present in a + certificate that also has a "basicConstraints" extension, then + "cA" is set to "TRUE" in that extension. Alternatively, a CA could + be issued a certificate in which "keyCertSign" is asserted without + "basicConstraints" being present; and an entity that acts as a CA + could be issued a certificate with "keyUsage" set to other values, + either with or without "keyCertSign". + + $ CA domain + (N) /PKI/ A security policy domain that "consists of a CA and its + subjects [i.e., the entities named in the certificates issued by + the CA]. Sometimes referred to as a PKI domain." [PAG] (See: + domain.) + + $ Caesar cipher + (I) A cipher that is defined for an alphabet of N characters, + A(1), A(2), ..., A(N), and creates cipher text by replacing each + plaintext character A(i) by A(i+K, mod N) for some 0<K<N+1. [Schn] + + Examples: (a) During the Gallic wars, Julius Caesar used a cipher + with K=3. In a Caesar cipher with K=3 for the English alphabet, A + is replaced by D, B by E, C by F, ..., W by Z, X by A, Y by B, Z + + + + +Shirey Informational [Page 44] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + by C. (b) UNIX systems sometimes include "ROT13" software that + implements a Caesar cipher with K=13 (i.e., ROTate by 13). + + $ call back + (I) An authentication technique for terminals that remotely access + a computer via telephone lines; the host system disconnects the + caller and then reconnects on a telephone number that was + previously authorized for that terminal. + + $ CAM + (O) See: Certificate Arbitrator Module. + + $ CANEWARE + (O) An end-to-end encryption system for computer data networks + that was developed by the U.S. DoD in the 1980s to provide host- + to-host data confidentiality service for datagrams in OSIRM Layer + 3. [Roge] (Compare: BLACKER, IPsec.) + + Tutorial: Each user host connects to its own bump-in-the-wire + encryption device called a CANEWARE Front End (CFE), through which + the host connects to the subnetwork. CANEWARE uses symmetric + encryption for CFE-to-CFE traffic, but also uses FIREFLY to + establish those session keys. The public-key certificates issued + by the FIREFLY system include credentials for mandatory access + control. For discretionary access control, the system also + includes one or more centralized CANEWARE Control Processors + (CCPs) that connect to the subnetwork, maintain a database for + discretionary access control authorizations, and communicate those + authorizations to assigned sets of CFEs. + + The CANEWARE system is MLS in only two of the three ways that + BLACKER is MLS: (a) Like BLACKER BFEs, CFEs form a security + perimeter around a subnetwork, separating user hosts from the + subnetwork, so that the subnetwork can operate at a different + security level than the hosts. (b) Like BLACKER, the CANEWARE + components are trusted to separate datagrams of different security + levels, so that each datagram of a given security level can be + received only by a host that is authorized for that security + level; and thus CANEWARE can separate host communities that + operate at different security levels. (c) Unlike a BFE, the host + side of a CFE is not MLS, and treats all packets received from a + user host as being at the same mandatory security level. + + $ capability list + (I) /information system/ A mechanism that implements access + control for a system entity by enumerating the system resources + that the entity is permitted to access and, either implicitly or + explicitly, the access modes granted for each resource. (Compare: + + + +Shirey Informational [Page 45] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + access control list, access control matrix, access profile, + capability token.) + + $ capability token + (I) A token (usually an unforgeable data object) that gives the + bearer or holder the right to access a system resource. Possession + of the token is accepted by a system as proof that the holder has + been authorized to access the resource indicated by the token. + (See: attribute certificate, capability list, credential, digital + certificate, ticket, token.) + + $ Capability Maturity Model (CMM) + (N) Method for judging the maturity of software processes in an + organization and for identifying crucial practices needed to + increase process maturity. [Chris] (Compare: Common Criteria.) + + Tutorial: The CMM does not specify security evaluation criteria + (see: assurance level), but its use may improve security + assurance. The CMM describes principles and practices that can + improve software processes in terms of evolving from ad hoc + processes to disciplined processes. The CMM has five levels: + - Initial: Software processes are ad hoc or chaotic, and few are + well-defined. Success depends on individual effort and heroics. + - Repeatable: Basic project management processes are established + to track cost, schedule, and functionality. Necessary process + discipline is in place to repeat earlier successes on projects + with similar applications. + - Defined: Software process for both management and engineering + activities is documented, standardized, and integrated into a + standard software process for the organization. Each project + uses an approved, tailored version of the organization's + standard process for developing and maintaining software. + - Managed: Detailed measures of software process and product + quality are collected. Both software process and products are + quantitatively understood and controlled. + - Optimizing: Continuous process improvement is enabled by + quantitative feedback from the process and from piloting + innovative ideas and technologies. + + $ CAPI + (I) See: cryptographic application programming interface. + + $ CAPSTONE + (N) An integrated microcircuit (in MYK-8x series manufactured by + Mykotronx, Inc.) that implements SKIPJACK, KEA, DSA, SHA, and + basic mathematical functions needed to support asymmetric + cryptography; has a non-deterministic random number generator; and + supports key escrow. (See: FORTEZZA. Compare: CLIPPER.) + + + +Shirey Informational [Page 46] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ card + See: cryptographic card, FORTEZZA, payment card, PC card, smart + card, token. + + $ card backup + See: token backup. + + $ card copy + See: token copy. + + $ card restore + See: token restore. + + $ cardholder + 1. (I) An entity to whom or to which a card has been issued. + + Usage: Usually refers to a living human being, but might refer (a) + to a position (see: billet, role) in an organization or (b) to an + automated process. (Compare: user.) + + 2. (O) /SET/ "The holder of a valid payment card account and user + of software supporting electronic commerce." [SET2] A cardholder + is issued a payment card by an issuer. SET ensures that in the + cardholder's interactions with merchants, the payment card account + information remains confidential. [SET1] + + $ cardholder certificate + (O) /SET/ A digital certificate that is issued to a cardholder + upon approval of the cardholder's issuing financial institution + and that is transmitted to merchants with purchase requests and + encrypted payment instructions, carrying assurance that the + account number has been validated by the issuing financial + institution and cannot be altered by a third party. [SET1] + + $ cardholder certification authority (CCA) + (O) /SET/ A CA responsible for issuing digital certificates to + cardholders and operated on behalf of a payment card brand, an + issuer, or another party according to brand rules. A CCA maintains + relationships with card issuers to allow for the verification of + cardholder accounts. A CCA does not issue a CRL but does + distribute CRLs issued by root CAs, brand CAs, geopolitical CAs, + and payment gateway CAs. [SET2] + + $ CAST + (N) A design procedure for symmetric encryption algorithms, and a + resulting family of algorithms, invented by Carlisle Adams (C.A.) + and Stafford Tavares (S.T.). [R2144, R2612] + + + + +Shirey Informational [Page 47] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ category + (I) A grouping of sensitive information items to which a non- + hierarchical restrictive security label is applied to increase + protection of the data. (See: formal access approval. Compare: + compartment, classification.) + + $ CAW + (N) See: certification authority workstation. + + $ CBC + (N) See: cipher block chaining. + + $ CCA + (O) See: cardholder certification authority. + + $ CCEP + (O) See: Commercial COMSEC Endorsement Program. + + $ CCI + (O) See: Controlled Cryptographic Item. + + $ CCITT + (N) Acronym for French translation of International Telephone and + Telegraph Consultative Committee. Now renamed ITU-T. + + $ CCM + (N) See: Counter with Cipher Block Chaining-Message Authentication + Code. + + $ CERIAS + (O) Purdue University's Center for Education and Research in + Information Assurance and Security, which includes faculty from + multiple schools and departments and takes a multidisciplinary + approach to security problems ranging from technical to ethical, + legal, educational, communicational, linguistic, and economic. + + $ CERT + (I) See: computer emergency response team. + + $ certificate + 1. (I) /general English/ A document that attests to the truth of + something or the ownership of something. + + 2. (I) /general security/ See: capability token, digital + certificate. + + 3. (I) /PKI/ See: attribute certificate, public-key certificate. + + + + +Shirey Informational [Page 48] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ Certificate Arbitrator Module (CAM) + (O) An open-source software module that is designed to be + integrated with an application for routing, replying to, and + otherwise managing and meditating certificate validation requests + between that application and the CAs in the ACES PKI. + + $ certificate authority + (D) Synonym for "certification authority". + + Deprecated Term: IDOCs SHOULD NOT use this term; it suggests + careless use of the term "certification authority", which is + preferred in PKI standards (e.g., [X509, R3280]). + + $ certificate chain + (D) Synonym for "certification path". (See: trust chain.) + + Deprecated Term: IDOCs SHOULD NOT use this term; it duplicates the + meaning of a standardized term. Instead, use "certification path". + + $ certificate chain validation + (D) Synonym for "certificate validation" or "path validation". + + Deprecated Term: IDOCs SHOULD NOT use this term; it duplicates the + meaning of standardized terms and mixes concepts in a potentially + misleading way. Instead, use "certificate validation" or "path + validation", depending on what is meant. (See: validate vs. + verify.) + + $ certificate creation + (I) The act or process by which a CA sets the values of a digital + certificate's data fields and signs it. (See: issue.) + + $ certificate expiration + (I) The event that occurs when a certificate ceases to be valid + because its assigned lifetime has been exceeded. (See: certificate + revocation, expire.) + + Tutorial: The assigned lifetime of an X.509 certificate is stated + in the certificate itself. (See: validity period.) + + $ certificate extension + (I) See: extension. + + $ certificate holder + (D) Synonym for the "subject" of a digital certificate. (Compare: + certificate owner, certificate user.) + + + + + +Shirey Informational [Page 49] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Deprecated Definition: IDOCs SHOULD NOT use this term as a synonym + for the subject of a digital certificate; the term is potentially + ambiguous. For example, the term could be misunderstood as + referring to a system entity or component, such as a repository, + that simply has possession of a copy of the certificate. + + $ certificate management + (I) The functions that a CA may perform during the lifecycle of a + digital certificate, including the following: + - Acquire and verify data items to bind into the certificate. + - Encode and sign the certificate. + - Store the certificate in a directory or repository. + - Renew, rekey, and update the certificate. + - Revoke the certificate and issue a CRL. + (See: archive management, certificate management, key management, + security architecture, token management.) + + $ certificate management authority (CMA) + (D) /U.S. DoD/ Used to mean either a CA or an RA. [DoD7, SP32] + + Deprecated Term: IDOCs SHOULD NOT use this term because it is + potentially ambiguous, such as in a context involving ICRLs. + Instead, use CA, RA, or both, depending on what is meant. + + $ certificate owner + (D) Synonym for the "subject" of a digital certificate. (Compare: + certificate holder, certificate user.) + + Deprecated Definition: IDOCs SHOULD NOT use this term as a synonym + for the subject of a digital certificate; the term is potentially + ambiguous. For example, the term could refer to a system entity, + such as a corporation, that has purchased a certificate to operate + equipment, such as a Web server. + + $ certificate path + (D) Synonym for "certification path". + + Deprecated Term: IDOCs SHOULD NOT use this term; it suggests + careless use of "certification path", which is preferred in PKI + standards (e.g., [X509, R3280]). + + $ certificate policy + (I) "A named set of rules that indicates the applicability of a + certificate to a particular community and/or class of application + with common security requirements." [X509] (Compare: CPS, security + policy.) + + + + + +Shirey Informational [Page 50] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Example: U.S. DoD's certificate policy [DoD7] defined four classes + (i.e., assurance levels) for X.509 public-key certificates and + defines the applicability of those classes. (See: class 2.) + + Tutorial: A certificate policy can help a certificate user to + decide whether a certificate should be trusted in a particular + application. "For example, a particular certificate policy might + indicate applicability of a type of certificate for the + authentication of electronic data interchange transactions for the + trading of goods within a given price range." [R3647] + + A v3 X.509 public-key certificate may have a "certificatePolicies" + extension that lists certificate policies, recognized by the + issuing CA, that apply to the certificate and govern its use. Each + policy is denoted by an object identifier and may optionally have + certificate policy qualifiers. (See: certificate profile.) + + Each SET certificate specifies at least one certificate policy, + that of the SET root CA. SET uses certificate policy qualifiers to + point to the actual policy statement and to add qualifying + policies to the root policy. (See: SET qualifier.) + + $ certificate policy qualifier + (I) Information that pertains to a certificate policy and is + included in a "certificatePolicies" extension in a v3 X.509 + public-key certificate. + + $ certificate profile + (I) A specification (e.g., [DoD7, R3280]) of the format and + semantics of public-key certificates or attribute certificates, + constructed for use in a specific application context by selecting + from among options offered by a broader standard. (Compare: + protection profile.) + + $ certificate reactivation + (I) The act or process by which a digital certificate, that a CA + has designated for revocation but not yet listed on a CRL, is + returned to the valid state. + + $ certificate rekey + 1. (I) The act or process by which an existing public-key + certificate has its key value changed by issuing a new certificate + with a different (usually new) public key. (See: certificate + renewal, certificate update, rekey.) + + Tutorial: For an X.509 public-key certificate, the essence of + rekey is that the subject stays the same and a new public key is + bound to that subject. Other changes are made, and the old + + + +Shirey Informational [Page 51] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + certificate is revoked, only as required by the PKI and CPS in + support of the rekey. If changes go beyond that, the process is a + "certificate update". + + 2. (O) /MISSI/ The act or process by which a MISSI CA creates a + new X.509 public-key certificate that is identical to the old one, + except the new one has (a) a new, different KEA key or (b) a new, + different DSS key or (c) new, different KEA and DSS keys. The new + certificate also has a different serial number and may have a + different validity period. A new key creation date and maximum key + lifetime period are assigned to each newly generated key. If a new + KEA key is generated, that key is assigned a new KMID. The old + certificate remains valid until it expires, but may not be further + renewed, rekeyed, or updated. + + $ certificate renewal + (I) The act or process by which the validity of the binding + asserted by an existing public-key certificate is extended in time + by issuing a new certificate. (See: certificate rekey, certificate + update.) + + Tutorial: For an X.509 public-key certificate, this term means + that the validity period is extended (and, of course, a new serial + number is assigned) but the binding of the public key to the + subject and to other data items stays the same. The other data + items are changed, and the old certificate is revoked, only as + required by the PKI and CPS to support the renewal. If changes go + beyond that, the process is a "certificate rekey" or "certificate + update". + + $ certificate request + (D) Synonym for "certification request". + + Deprecated Term: IDOCs SHOULD NOT use this term; it suggests + careless use of the term "certification request", which is + preferred in PKI standards (e.g., see PKCS #10). + + $ certificate revocation + (I) The event that occurs when a CA declares that a previously + valid digital certificate issued by that CA has become invalid; + usually stated with an effective date. + + Tutorial: In X.509, a revocation is announced to potential + certificate users by issuing a CRL that mentions the certificate. + Revocation and listing on a CRL is only necessary prior to the + certificate's scheduled expiration. + + + + + +Shirey Informational [Page 52] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ certificate revocation list (CRL) + 1. (I) A data structure that enumerates digital certificates that + have been invalidated by their issuer prior to when they were + scheduled to expire. (See: certificate expiration, delta CRL, + X.509 certificate revocation list.) + + 2. (O) "A signed list indicating a set of certificates that are no + longer considered valid by the certificate issuer. In addition to + the generic term CRL, some specific CRL types are defined for CRLs + that cover particular scopes." [X509] + + $ certificate revocation tree + (N) A mechanism for distributing notices of certificate + revocations; uses a tree of hash results that is signed by the + tree's issuer. Offers an alternative to issuing a CRL, but is not + supported in X.509. (See: certificate status responder.) + + $ certificate serial number + 1. (I) An integer value that (a) is associated with, and may be + carried in, a digital certificate; (b) is assigned to the + certificate by the certificate's issuer; and (c) is unique among + all the certificates produced by that issuer. + + 2. (O) "An integer value, unique within the issuing CA, [that] is + unambiguously associated with a certificate issued by that CA." + [X509] + + $ certificate status authority + (D) /U.S. DoD/ "A trusted entity that provides on-line + verification to a Relying Party of a subject certificate's + trustworthiness [should instead say 'validity'], and may also + provide additional attribute information for the subject + certificate." [DoD7] + + Deprecated Term: IDOCs SHOULD NOT use this term because it is not + widely accepted; instead, use "certificate status responder" or + "OCSP server", or otherwise explain what is meant. + + $ certificate status responder + (N) /FPKI/ A trusted online server that acts for a CA to provide + authenticated certificate status information to certificate users + [FPKI]. Offers an alternative to issuing a CR. (See: certificate + revocation tree, OCSP.) + + $ certificate update + (I) The act or process by which non-key data items bound in an + existing public-key certificate, especially authorizations granted + + + + +Shirey Informational [Page 53] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + to the subject, are changed by issuing a new certificate. (See: + certificate rekey, certificate renewal.) + + Usage: For an X.509 public-key certificate, the essence of this + process is that fundamental changes are made in the data that is + bound to the public key, such that it is necessary to revoke the + old certificate. (Otherwise, the process is only a "certificate + rekey" or "certificate renewal".) + + $ certificate user + 1. (I) A system entity that depends on the validity of information + (such as another entity's public key value) provided by a digital + certificate. (See: relying party. Compare: /digital certificate/ + subject.) + + Usage: The depending entity may be a human being or an + organization, or a device or process controlled by a human or + organization. (See: user.) + + 2. (O) "An entity that needs to know, with certainty, the public + key of another entity." [X509] + + 3. (D) Synonym for "subject" of a digital certificate. + + Deprecated Definition: IDOCs SHOULD NOT use this term with + definition 3; the term could be confused with one of the other two + definitions given above. + + $ certificate validation + 1. (I) An act or process by which a certificate user establishes + that the assertions made by a digital certificate can be trusted. + (See: valid certificate, validate vs. verify.) + + 2. (O) "The process of ensuring that a certificate was valid at a + given time, including possibly the construction and processing of + a certification path [R4158], and ensuring that all certificates + in that path were valid (i.e. were not expired or revoked) at that + given time." [X509] + + Tutorial: To validate a certificate, a certificate user checks + that the certificate is properly formed and signed and is + currently in force: + - Checks the syntax and semantics: Parses the certificate's + syntax and interprets its semantics, applying rules specified + for and by its data fields, such as for critical extensions in + an X.509 certificate. + + + + + +Shirey Informational [Page 54] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + - Checks the signature: Uses the issuer's public key to verify + the digital signature of the CA who issued the certificate in + question. If the verifier obtains the issuer's public key from + the issuer's own public-key certificate, that certificate + should be validated, too. That validation may lead to yet + another certificate to be validated, and so on. Thus, in + general, certificate validation involves discovering and + validating a certification path. + - Checks currency and revocation: Verifies that the certificate + is currently in force by checking that the current date and + time are within the validity period (if that is specified in + the certificate) and that the certificate is not listed on a + CRL or otherwise announced as invalid. (The CRLs also must be + checked by a similar validation process.) + + $ certification + 1. (I) /information system/ Comprehensive evaluation (usually made + in support of an accreditation action) of an information system's + technical security features and other safeguards to establish the + extent to which the system's design and implementation meet a set + of specified security requirements. [C4009, FP102, SP37] (See: + accreditation. Compare: evaluation.) + + 2. (I) /digital certificate/ The act or process of vouching for + the truth and accuracy of the binding between data items in a + certificate. (See: certify.) + + 3. (I) /PKI/ The act or process of vouching for the ownership of a + public key by issuing a public-key certificate that binds the key + to the name of the entity that possesses the matching private key. + Besides binding a key with a name, a public-key certificate may + bind those items with other restrictive or explanatory data items. + (See: X.509 public-key certificate.) + + 4. (O) /SET/ "The process of ascertaining that a set of + requirements or criteria has been fulfilled and attesting to that + fact to others, usually with some written instrument. A system + that has been inspected and evaluated as fully compliant with the + SET protocol by duly authorized parties and process would be said + to have been certified compliant." [SET2] + + $ certification authority (CA) + 1. (I) An entity that issues digital certificates (especially + X.509 certificates) and vouches for the binding between the data + items in a certificate. + + + + + + +Shirey Informational [Page 55] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + 2. (O) "An authority trusted by one or more users to create and + assign certificates. Optionally the certification authority may + create the user's keys." [X509] + + Tutorial: Certificate users depend on the validity of information + provided by a certificate. Thus, a CA should be someone that + certificate users trust and that usually holds an official + position created and granted power by a government, a corporation, + or some other organization. A CA is responsible for managing the + life cycle of certificates (see: certificate management) and, + depending on the type of certificate and the CPS that applies, may + be responsible for the lifecycle of key pairs associated with the + certificates (see: key management). + + $ certification authority workstation (CAW) + (N) A computer system that enables a CA to issue digital + certificates and supports other certificate management functions + as required. + + $ certification hierarchy + 1. (I) A tree-structured (loop-free) topology of relationships + between CAs and the entities to whom the CAs issue public-key + certificates. (See: hierarchical PKI, hierarchy management.) + + Tutorial: In this structure, one CA is the top CA, the highest + level of the hierarchy. (See: root, top CA.) The top CA may issue + public-key certificates to one or more additional CAs that form + the second-highest level. Each of these CAs may issue certificates + to more CAs at the third-highest level, and so on. The CAs at the + second-lowest level issue certificates only to non-CA entities + that form the lowest level (see: end entity). Thus, all + certification paths begin at the top CA and descend through zero + or more levels of other CAs. All certificate users base path + validations on the top CA's public key. + + 2. (I) /PEM/ A certification hierarchy for PEM has three levels of + CAs [R1422]: + - The highest level is the "Internet Policy Registration + Authority". + - A CA at the second-highest level is a "policy certification + authority". + - A CA at the third-highest level is a "certification authority". + + 3. (O) /MISSI/ A certification hierarchy for MISSI has three or + four levels of CAs: + - A CA at the highest level, the top CA, is a "policy approving + authority". + + + + +Shirey Informational [Page 56] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + - A CA at the second-highest level is a "policy creation + authority". + - A CA at the third-highest level is a local authority called a + "certification authority". + - A CA at the fourth-highest (optional) level is a "subordinate + certification authority". + + 4. (O) /SET/ A certification hierarchy for SET has three or four + levels of CAs: + - The highest level is a "SET root CA". + - A CA at the second-highest level is a "brand certification + authority". + - A CA at the third-highest (optional) level is a "geopolitical + certification authority". + - A CA at the fourth-highest level is a "cardholder CA", a + "merchant CA", or a "payment gateway CA". + + $ certification path + 1. (I) A linked sequence of one or more public-key certificates, + or one or more public-key certificates and one attribute + certificate, that enables a certificate user to verify the + signature on the last certificate in the path, and thus enables + the user to obtain (from that last certificate) a certified public + key, or certified attributes, of the system entity that is the + subject of that last certificate. (See: trust anchor, certificate + validation, valid certificate.) + + 2. (O) "An ordered sequence of certificates of objects in the + [X.500 Directory Information Tree] which, together with the public + key of the initial object in the path, can be processed to obtain + that of the final object in the path." [R3647, X509] + + Tutorial: The list is "linked" in the sense that the digital + signature of each certificate (except possibly the first) is + verified by the public key contained in the preceding certificate; + i.e., the private key used to sign a certificate and the public + key contained in the preceding certificate form a key pair that + has previously been bound to the authority that signed. + + The path is the "list of certificates needed to [enable] a + particular user to obtain the public key [or attributes] of + another [user]." [X509] Here, the word "particular" points out + that a certification path that can be validated by one certificate + user might not be able to be validated by another. That is because + either the first certificate needs to be a trusted certificate or + the signature on the first certificate needs to be verifiable by a + trusted key (e.g., a root key), but such trust is established only + + + + +Shirey Informational [Page 57] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + relative to a "particular" (i.e., specific) user, not absolutely + for all users. + + $ certification policy + (D) Synonym for either "certificate policy" or "certification + practice statement". + + Deprecated Term: IDOCs SHOULD NOT use this term as a synonym for + either of those terms; that would be duplicative and would mix + concepts in a potentially misleading way. Instead, use either + "certificate policy" or "certification practice statement", + depending on what is meant. + + $ certification practice statement (CPS) + (I) "A statement of the practices which a certification authority + employs in issuing certificates." [DSG, R3647] (See: certificate + policy.) + + Tutorial: A CPS is a published security policy that can help a + certificate user to decide whether a certificate issued by a + particular CA can be trusted enough to use in a particular + application. A CPS may be (a) a declaration by a CA of the details + of the system and practices it uses in its certificate management + operations, (b) part of a contract between the CA and an entity to + whom a certificate is issued, (c) a statute or regulation + applicable to the CA, or (d) a combination of these types + involving multiple documents. [DSG] + + A CPS is usually more detailed and procedurally oriented than a + certificate policy. A CPS applies to a particular CA or CA + community, while a certificate policy applies across CAs or + communities. A CA with its single CPS may support multiple + certificate policies, which may be used for different application + purposes or by different user communities. On the other hand, + multiple CAs, each with a different CPS, may support the same + certificate policy. [R3647] + + $ certification request + (I) An algorithm-independent transaction format (e.g., PKCS #10, + RFC 4211) that contains a DN, and a public key or, optionally, a + set of attributes, collectively signed by the entity requesting + certification, and sent to a CA, which transforms the request to + an X.509 public-key certificate or another type of certificate. + + $ certify + 1. (I) Issue a digital certificate and thus vouch for the truth, + accuracy, and binding between data items in the certificate (e.g., + "X.509 public-key certificate"), such as the identity of the + + + +Shirey Informational [Page 58] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + certificate's subject and the ownership of a public key. (See: + certification.) + + Usage: To "certify a public key" means to issue a public-key + certificate that vouches for the binding between the certificate's + subject and the key. + + 2. (I) The act by which a CA uses measures to verify the truth, + accuracy, and binding between data items in a digital certificate. + + Tutorial: A description of the measures used for verification + should be included in the CA's CPS. + + $ CFB + (N) See: cipher feedback. + + $ chain + (D) See: trust chain. + + $ Challenge Handshake Authentication Protocol (CHAP) + (I) A peer entity authentication method (employed by PPP and other + protocols, e.g., RFC 3720) that uses a randomly generated + challenge and requires a matching response that depends on a + cryptographic hash of some combination of the challenge and a + secret key. [R1994] (See: challenge-response, PAP.) + + $ challenge-response + (I) An authentication process that verifies an identity by + requiring correct authentication information to be provided in + response to a challenge. In a computer system, the authentication + information is usually a value that is required to be computed in + response to an unpredictable challenge value, but it might be just + a password. + + $ Challenge-Response Authentication Mechanism (CRAM) + (I) /IMAP4/ A mechanism [R2195], intended for use with IMAP4 + AUTHENTICATE, by which an IMAP4 client uses a keyed hash [R2104] + to authenticate itself to an IMAP4 server. (See: POP3 APOP.) + + Tutorial: The server includes a unique time stamp in its ready + response to the client. The client replies with the client's name + and the hash result of applying MD5 to a string formed from + concatenating the time stamp with a shared secret that is known + only to the client and the server. + + $ channel + 1. (I) An information transfer path within a system. (See: covert + channel.) + + + +Shirey Informational [Page 59] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + 2. (O) "A subdivision of the physical medium allowing possibly + shared independent uses of the medium." (RFC 3753) + + $ channel capacity + (I) The total capacity of a link to carry information; usually + expressed in bits per second. (RFC 3753) (Compare: bandwidth.) + + Tutorial: Within a given bandwidth, the theoretical maximum + channel capacity is given by Shannon's Law. The actual channel + capacity is determined by the bandwidth, the coding system used, + and the signal-to-noise ratio. + + $ CHAP + (I) See: Challenge Handshake Authentication Protocol. + + $ checksum + (I) A value that (a) is computed by a function that is dependent + on the contents of a data object and (b) is stored or transmitted + together with the object, for detecting changes in the data. (See: + cyclic redundancy check, data integrity service, error detection + code, hash, keyed hash, parity bit, protected checksum.) + + Tutorial: To gain confidence that a data object has not been + changed, an entity that later uses the data can independently + recompute the checksum value and compare the result with the value + that was stored or transmitted with the object. + + Computer systems and networks use checksums (and other mechanisms) + to detect accidental changes in data. However, active wiretapping + that changes data could also change an accompanying checksum to + match the changed data. Thus, some checksum functions by + themselves are not good countermeasures for active attacks. To + protect against active attacks, the checksum function needs to be + well-chosen (see: cryptographic hash), and the checksum result + needs to be cryptographically protected (see: digital signature, + keyed hash). + + $ Chinese wall policy + (I) A security policy to prevent conflict of interest caused by an + entity (e.g., a consultant) interacting with competing firms. + (See: Brewer-Nash model.) + + Tutorial: All information is categorized into mutually exclusive + conflict-of-interest classes I(1), I(2), ..., I(M), and each firm + F(1), F(2), ..., F(N) belongs to exactly one class. The policy + states that if a consultant has access to class I(i) information + from a firm in that class, then the consultant may not access + information from another firm in that same class, but may access + + + +Shirey Informational [Page 60] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + information from another firm that is in a different class. Thus, + the policy creates a barrier to communication between firms that + are in the same conflict-of-interest class. Brewer and Nash + modeled enforcement of this policy [BN89], including dealing with + policy violations that could occur because two or more consultants + work for the same firm. + + $ chosen-ciphertext attack + (I) A cryptanalysis technique in which the analyst tries to + determine the key from knowledge of plain text that corresponds to + cipher text selected (i.e., dictated) by the analyst. + + $ chosen-plaintext attack + (I) A cryptanalysis technique in which the analyst tries to + determine the key from knowledge of cipher text that corresponds + to plain text selected (i.e., dictated) by the analyst. + + $ CIAC + (O) See: Computer Incident Advisory Capability. + + $ CIK + (N) See: cryptographic ignition key. + + $ cipher + (I) A cryptographic algorithm for encryption and decryption. + + $ cipher block chaining (CBC) + (N) A block cipher mode that enhances ECB mode by chaining + together blocks of cipher text it produces. [FP081] (See: block + cipher, [R1829], [R2405], [R2451], [SP38A].) + + Tutorial: This mode operates by combining (exclusive OR-ing) the + algorithm's ciphertext output block with the next plaintext block + to form the next input block for the algorithm. + + $ cipher feedback (CFB) + (N) A block cipher mode that enhances ECB mode by chaining + together the blocks of cipher text it produces and operating on + plaintext segments of variable length less than or equal to the + block length. [FP081] (See: block cipher, [SP38A].) + + Tutorial: This mode operates by using the previously generated + ciphertext segment as the algorithm's input (i.e., by "feeding + back" the cipher text) to generate an output block, and then + combining (exclusive OR-ing) that output block with the next + plaintext segment (block length or less) to form the next + ciphertext segment. + + + + +Shirey Informational [Page 61] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ cipher text + 1. (I) /noun/ Data that has been transformed by encryption so that + its semantic information content (i.e., its meaning) is no longer + intelligible or directly available. (See: ciphertext. Compare: + clear text, plain text.) + + 2. (O) "Data produced through the use of encipherment. The + semantic content of the resulting data is not available." + [I7498-2] + + $ ciphertext + 1. (O) /noun/ Synonym for "cipher text" [I7498-2]. + + 2. (I) /adjective/ Referring to cipher text. Usage: Commonly used + instead of "cipher-text". (Compare: cleartext, plaintext.) + + $ ciphertext auto-key (CTAK) + (D) "Cryptographic logic that uses previous cipher text to + generate a key stream." [C4009, A1523] (See: KAK.) + + Deprecated Term: IDOCs SHOULD NOT use this term; it is neither + well-known nor precisely defined. Instead, use terms associated + with modes that are defined in standards, such as CBC, CFB, and + OFB. + + $ ciphertext-only attack + (I) A cryptanalysis technique in which the analyst tries to + determine the key solely from knowledge of intercepted cipher text + (although the analyst may also know other clues, such as the + cryptographic algorithm, the language in which the plain text was + written, the subject matter of the plain text, and some probable + plaintext words.) + + $ ciphony + (O) The process of encrypting audio information. + + $ CIPSO + (I) See: Common IP Security Option. + + $ CKL + (I) See: compromised key list. + + $ Clark-Wilson model + (N) A security model [Clark] to maintain data integrity in the + commercial world. (Compare: Bell-LaPadula model.) + + + + + + +Shirey Informational [Page 62] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ class 2, 3, 4, 5 + (O) /U.S. DoD/ Assurance levels for PKIs, and for X.509 public-key + certificates issued by a PKI. [DoD7] (See: "first law" under + "Courtney's laws".) + - "Class 2": Intended for applications handling unclassified, + low-value data in minimally or moderately protected + environments. + - "Class 3": Intended for applications handling unclassified, + medium-value data in moderately protected environments, or + handling unclassified or high-value data in highly protected + environments, and for discretionary access control of + classified data in highly protected environments. + - "Class 4": Intended for applications handling unclassified, + high-value data in minimally protected environments. + - "Class 5": Intended for applications handling classified data + in minimally protected environments, and for authentication of + material that would affect the security of classified systems. + + The environments are defined as follows: + - "Highly protected environment": Networks that are protected + either with encryption devices approved by NSA for protection + of classified data or via physical isolation, and that are + certified for processing system-high classified data, where + exposure of unencrypted data is limited to U.S. citizens + holding appropriate security clearances. + - "Moderately protected environment": + -- Physically isolated unclassified, unencrypted networks in + which access is restricted based on legitimate need. + -- Networks protected by NSA-approved, type 1 encryption, + accessible by U.S.-authorized foreign nationals. + - "Minimally protected environments": Unencrypted networks + connected to either the Internet or NIPRNET, either directly or + via a firewall. + + $ Class A1, B3, B2, B1, C2, or C1 computer system + (O) /TCSEC/ See: Tutorial under "Trusted Computer System + Evaluation Criteria". + + $ classification + 1. (I) A grouping of classified information to which a + hierarchical, restrictive security label is applied to increase + protection of the data from unauthorized disclosure. (See: + aggregation, classified, data confidentiality service. Compare: + category, compartment.) + + 2. (I) An authorized process by which information is determined to + be classified and assigned to a security level. (Compare: + declassification.) + + + +Shirey Informational [Page 63] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Usage: Usually understood to involve data confidentiality, but + IDOCs SHOULD make this clear when data also is sensitive in other + ways and SHOULD use other terms for those other sensitivity + concepts. (See: sensitive information, data integrity.) + + $ classification label + (I) A security label that tells the degree of harm that will + result from unauthorized disclosure of the labeled data, and may + also tell what countermeasures are required to be applied to + protect the data from unauthorized disclosure. Example: IPSO. + (See: classified, data confidentiality service. Compare: integrity + label.) + + Usage: Usually understood to involve data confidentiality, but + IDOCs SHOULD make this clear when data also is sensitive in other + ways and SHOULD use other terms for those other sensitivity + concepts. (See: sensitive information, data integrity.) + + $ classification level + (I) A hierarchical level of protection (against unauthorized + disclosure) that is required to be applied to certain classified + data. (See: classified. Compare: security level.) + + Usage: Usually understood to involve data confidentiality, but + IDOCs SHOULD make this clear when data also is sensitive in other + ways and SHOULD use other terms for those other sensitivity + concepts. (See: sensitive information, data integrity.) + + $ classified + 1. (I) Refers to information (stored or conveyed, in any form) + that is formally required by a security policy to receive data + confidentiality service and to be marked with a security label + (which, in some cases, might be implicit) to indicate its + protected status. (See: classify, collateral information, SAP, + security level. Compare: unclassified.) + + Usage: Usually understood to involve data confidentiality, but + IDOCs SHOULD make this clear when data also is sensitive in other + ways and SHOULD use other terms for those other sensitivity + concepts. (See: sensitive information, data integrity.) + + Mainly used by national governments, especially by the military, + but the underlying concept also applies outside of governments. + + 2. (O) /U.S. Government/ "Information that has been determined + pursuant to Executive Order 12958 or any predecessor Order, or by + the Atomic Energy Act of 1954, as amended, to require protection + + + + +Shirey Informational [Page 64] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + against unauthorized disclosure and is marked to indicate its + classified status." [C4009] + + $ classify + (I) To officially designate an information item or type of + information as being classified and assigned to a specific + security level. (See: classified, declassify, security level.) + + $ clean system + (I) A computer system in which the operating system and + application system software and files have been freshly installed + from trusted software distribution media. (Compare: secure state.) + + $ clear + (D) /verb/ Synonym for "erase". [C4009] + + Deprecated Definition: IDOCs SHOULD NOT use the term with this + definition; that could be confused with "clear text" in which + information is directly recoverable. + + $ clear text + 1. (I) /noun/ Data in which the semantic information content + (i.e., the meaning) is intelligible or is directly available, + i.e., not encrypted. (See: cleartext, in the clear. Compare: + cipher text, plain text.) + + 2. (O) /noun/ "Intelligible data, the semantic content of which is + available." [I7498-2] + + 3. (D) /noun/ Synonym for "plain text". + + Deprecated Definition: IDOCs SHOULD NOT use this term as a synonym + for "plain text", because the plain text that is input to an + encryption operation may itself be cipher text that was output + from a previous encryption operation. (See: superencryption.) + + $ clearance + See: security clearance. + + $ clearance level + (I) The security level of information to which a security + clearance authorizes a person to have access. + + $ cleartext + 1. (O) /noun/ Synonym for "clear text" [I7498-2]. + + 2. (I) /adjective/ Referring to clear text. Usage: Commonly used + instead of "clear-text". (Compare: ciphertext, plaintext.) + + + +Shirey Informational [Page 65] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + 3. (D) /adjective/ Synonym for "plaintext". + + Deprecated Definition: IDOCs SHOULD NOT use this term as a synonym + for "plaintext", because the plaintext data that is input to an + encryption operation may itself be ciphertext data that was output + from a previous encryption operation. (See: superencryption.) + + $ CLEF + (N) See: commercially licensed evaluation facility. + + $ client + (I) A system entity that requests and uses a service provided by + another system entity, called a "server". (See: server.) + + Tutorial: Usually, it is understood that the client and server are + automated components of the system, and the client makes the + request on behalf of a human user. In some cases, the server may + itself be a client of some other server. + + $ client-server system + (I) A distributed system in which one or more entities, called + clients, request a specific service from one or more other + entities, called servers, that provide the service to the clients. + + Example: The Word Wide Web, in which component servers provide + information that is requested by component clients called + "browsers". + + $ CLIPPER + (N) An integrated microcircuit (in MYK-7x series manufactured by + Mykotronx, Inc.) that implements SKIPJACK, has a non-deterministic + random number generator, and supports key escrow. (See: Escrowed + Encryption Standard. Compare: CLIPPER.) + + Tutorial: The chip was mainly intended for protecting + telecommunications over the public switched network. The key + escrow scheme for the chip involves a SKIPJACK key that is common + to all chips and that protects the unique serial number of the + chip, and a second SKIPJACK key unique to the chip that protects + all data encrypted by the chip. The second key is escrowed as + split key components held by NIST and the U.S. Treasury + Department. + + $ closed security environment + (O) /U.S. DoD/ A system environment that meets both of the + following conditions: (a) Application developers (including + maintainers) have sufficient clearances and authorizations to + provide an acceptable presumption that they have not introduced + + + +Shirey Informational [Page 66] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + malicious logic. (b) Configuration control provides sufficient + assurance that system applications and the equipment they run on + are protected against the introduction of malicious logic prior to + and during the operation of applications. [NCS04] (See: "first + law" under "Courtney's laws". Compare: open security environment.) + + $ CMA + (D) See: certificate management authority. + + $ CMAC + (N) A message authentication code [SP38B] that is based on a + symmetric block cipher. (See: block cipher.) + + Derivation: Cipher-based MAC. (Compare: HMAC.) + + Tutorial: Because CMAC is based on approved, symmetric-key block + ciphers, such as AES, CMAC can be considered a mode of operation + for those block ciphers. (See: mode of operation.) + + $ CMCS + (O) See: COMSEC Material Control System. + + $ CMM + (N) See: Capability Maturity Model. + + $ CMS + (I) See: Cryptographic Message Syntax. + + $ code + 1. (I) A system of symbols used to represent information, which + might originally have some other representation. Examples: ASCII, + BER, country code, Morse code. (See: encode, object code, source + code.) + + Deprecated Abbreviation: To avoid confusion with definition 1, + IDOCs SHOULD NOT use "code" as an abbreviation of "country code", + "cyclic redundancy code", "Data Authentication Code", "error + detection code", or "Message Authentication Code". To avoid + misunderstanding, use the fully qualified term in these other + cases, at least at the point of first usage. + + 2. (I) /cryptography/ An encryption algorithm based on + substitution; i.e., a system for providing data confidentiality by + using arbitrary groups (called "code groups") of letters, numbers, + or symbols to represent units of plain text of varying length. + (See: codebook, cryptography.) + + + + + +Shirey Informational [Page 67] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Deprecated Usage: To avoid confusion with definition 1, IDOCs + SHOULD NOT use "code" as a synonym for any of the following terms: + (a) "cipher", "hash", or other words that mean "a cryptographic + algorithm"; (b) "cipher text"; or (c) "encrypt", "hash", or other + words that refer to applying a cryptographic algorithm. + + 3. (I) An algorithm based on substitution, but used to shorten + messages rather than to conceal their content. + + 4. (I) /computer programming/ To write computer software. (See: + object code, source code.) + + Deprecated Abbreviation: To avoid confusion with definition 1, + IDOCs SHOULD NOT use "code" as an abbreviation of "object code" or + "source code". To avoid misunderstanding, use the fully qualified + term in these other cases, at least at the point of first usage. + + $ code book + 1. (I) Document containing a systematically arranged list of + plaintext units and their ciphertext equivalents. [C4009] + + 2. (I) An encryption algorithm that uses a word substitution + technique. [C4009] (See: code, ECB.) + + $ code signing + (I) A security mechanism that uses a digital signature to provide + data integrity and data origin authentication for software that is + being distributed for use. (See: mobile code, trusted + distribution.) + + Tutorial: In some cases, the signature on a software module may + imply some assertion that the signer makes about the software. For + example, a signature may imply that the software has been + designed, developed, or tested according to some criterion. + + $ code word + (O) /U.S. Government/ A single word that is used as a security + label (usually applied to classified information) but which itself + has a classified meaning. (See: classified, /U.S. Government/ + security label.) + + $ COI + (I) See: community of interest. + + $ cold start + (N) /cryptographic module/ A procedure for initially keying + cryptographic equipment. [C4009] + + + + +Shirey Informational [Page 68] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ collateral information + (O) /U.S. Government/ Information that is classified but is not + required to be protected by an SAP. (See: /U.S. Government/ + classified.) + + $ color change + (I) In a system being operated in periods-processing mode, the act + of purging all information from one processing period and then + changing over to the next processing period. (See: BLACK, RED.) + + $ Commercial COMSEC Evaluation Program (CCEP) + (O) "Relationship between NSA and industry in which NSA provides + the COMSEC expertise (i.e., standards, algorithms, evaluations, + and guidance) and industry provides design, development, and + production capabilities to produce a type 1 or type 2 product." + [C4009] + + $ commercially licensed evaluation facility (CLEF) + (N) An organization that has official approval to evaluate the + security of products and systems under the Common Criteria, ITSEC, + or some other standard. (Compare: KLIF.) + + $ Committee on National Security Systems (CNSS) + (O) /U.S. Government/ A Government, interagency, standing + committee of the President's Critical Infrastructure Protection + Board. The CNSS is chaired by the Secretary of Defense and + provides a forum for the discussion of policy issues, sets + national policy, and promulgates direction, operational + procedures, and guidance for the security of national security + systems. The Secretary of Defense and the Director of Central + Intelligence are responsible for developing and overseeing the + implementation of Government-wide policies, principles, standards, + and guidelines for the security of systems that handle national + security information. + + $ Common Criteria for Information Technology Security + (N) A standard for evaluating information technology (IT) products + and systems. It states requirements for security functions and for + assurance measures. [CCIB] (See: CLEF, EAL, packages, protection + profile, security target, TOE. Compare: CMM.) + + Tutorial: Canada, France, Germany, the Netherlands, the United + Kingdom, and the United States (NIST and NSA) began developing + this standard in 1993, based on the European ITSEC, the Canadian + Trusted Computer Product Evaluation Criteria (CTCPEC), and the + U.S. "Federal Criteria for Information Technology Security" and + its precursor, the TCSEC. Work was done in cooperation with + ISO/IEC Joint Technical Committee 1 (Information Technology), + + + +Shirey Informational [Page 69] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Subcommittee 27 (Security Techniques), Working Group 3 (Security + Criteria). Version 2.0 of the Criteria has been issued as ISO's + International Standard 15408. The U.S. Government intends this + standard to supersede both the TCSEC and FIPS PUB 140. (See: + NIAP.) + + The standard addresses data confidentiality, data integrity, and + availability and may apply to other aspects of security. It + focuses on threats to information arising from human activities, + malicious or otherwise, but may apply to non-human threats. It + applies to security measures implemented in hardware, firmware, or + software. It does not apply to (a) administrative security not + related directly to technical security, (b) technical physical + aspects of security such as electromagnetic emanation control, (c) + evaluation methodology or administrative and legal framework under + which the criteria may be applied, (d) procedures for use of + evaluation results, or (e) assessment of inherent qualities of + cryptographic algorithms. + + Part 1, Introduction and General Model, defines general concepts + and principles of IT security evaluation; presents a general model + of evaluation; and defines constructs for expressing IT security + objectives, for selecting and defining IT security requirements, + and for writing high-level specifications for products and + systems. + + Part 2, Security Functional Requirements, contains a catalog of + well-defined and well-understood functional requirement statements + that are intended to be used as a standard way of expressing the + security requirements for IT products and systems. + + Part 3, Security Assurance Requirements, contains a catalog of + assurance components for use as a standard way of expressing such + requirements for IT products and systems, and defines evaluation + criteria for protection profiles and security targets. + + $ Common IP Security Option (CIPSO) + (I) See: secondary definition under "IPSO". + + $ common name + (N) A character string that (a) may be a part of the X.500 DN of a + Directory object ("commonName" attribute), (b) is a (possibly + ambiguous) name by which the object is commonly known in some + limited scope (such as an organization), and (c) conforms to the + naming conventions of the country or culture with which it is + associated. [X520] (See: "subject" and "issuer" under "X.509 + public-key certificate".) + + + + +Shirey Informational [Page 70] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Examples: "Dr. Albert Einstein", "The United Nations", and "12-th + Floor Laser Printer". + + $ communications cover + (N) "Concealing or altering of characteristic communications + patterns to hide information that could be of value to an + adversary." [C4009] (See: operations security, traffic-flow + confidentiality, TRANSEC.) + + $ communication security (COMSEC) + (I) Measures that implement and assure security services in a + communication system, particularly those that provide data + confidentiality and data integrity and that authenticate + communicating entities. + + Usage: COMSEC is usually understood to include (a) cryptography + and its related algorithms and key management methods and + processes, devices that implement those algorithms and processes, + and the lifecycle management of the devices and keying material. + Also, COMSEC is sometimes more broadly understood as further + including (b) traffic-flow confidentiality, (c) TRANSEC, and (d) + steganography [Kahn]. (See: cryptology, signal security.) + + $ community of interest (COI) + 1. (I) A set of entities that operate under a common security + policy. (Compare: domain.) + + 2. (I) A set of entities that exchange information collaboratively + for some purpose. + + $ community risk + (N) Probability that a particular vulnerability will be exploited + within an interacting population and adversely affect some members + of that population. [C4009] (See: Morris worm, risk.) + + $ community string + (I) A community name in the form of an octet string that serves as + a cleartext password in SNMP version 1 (RFC 1157) and version 2 + (RFC 1901). (See: password, Simple Network Management Protocol.) + + Tutorial: The SNMPv1 and SNMPv2 protocols have been declared + "historic" and have been replaced by the more secure SNMPv3 + standard (RFCs 3410-3418), which does not use cleartext passwords. + + + + + + + + +Shirey Informational [Page 71] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ compartment + 1. (I) A grouping of sensitive information items that require + special access controls beyond those normally provided for the + basic classification level of the information. (See: compartmented + security mode. Compare: category, classification.) + + Usage: The term is usually understood to include the special + handling procedures to be used for the information. + + 2. (I) Synonym for "category". + + Deprecated Usage: This Glossary defines "category" with a slightly + narrower meaning than "compartment". That is, a security label is + assigned to a category because the data owner needs to handle the + data as a compartment. However, a compartment could receive + special protection in a system without being assigned a category + label. + + $ compartmented security mode + (N) A mode of system operation wherein all users having access to + the system have the necessary security clearance for the single, + hierarchical classification level of all data handled by the + system, but some users do not have the clearance for a non- + hierarchical category of some data handled by the system. (See: + category, /system operation/ under "mode", protection level, + security clearance.) + + Usage: Usually abbreviated as "compartmented mode". This term was + defined in U.S. Government policy on system accreditation. In this + mode, a system may handle (a) a single hierarchical classification + level and (b) multiple non-hierarchical categories within that + level. + + $ Compartments field + (I) A 16-bit field (the "C field") that specifies compartment + values in the security option (option type 130) of version 4 IP's + datagram header format. The valid field values are assigned by the + U.S. Government, as specified in RFC 791. + + Deprecated Abbreviation: IDOCs SHOULD NOT use the abbreviation "C + field"; the abbreviation is potentially ambiguous. Instead, use + "Compartments field". + + $ component + See: system component. + + + + + + +Shirey Informational [Page 72] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ compression + (I) A process that encodes information in a way that minimizes the + number of resulting code symbols and thus reduces storage space or + transmission time. + + Tutorial: A data compression algorithm may be "lossless", i.e., + retain all information that was encoded in the data, so that + decompression can recover all the information; or an algorithm may + be "lossy". Text usually needs to be compressed losslessly, but + images are often compressed with lossy schemes. + + Not all schemes that encode information losslessly for machine + processing are efficient in terms of minimizing the number of + output bits. For example, ASCII encoding is lossless, but ASCII + data can often be losslessly reencoded in fewer bits with other + schemes. These more efficient schemes take advantage of some sort + of inherent imbalance, redundancy, or repetition in the data, such + as by replacing a character string in which all characters are the + same by a shorter string consisting of only the single character + and a character count. + + Lossless compression schemes cannot effectively reduce the number + of bits in cipher text produced by a strong encryption algorithm, + because the cipher text is essentially a pseudorandom bit string + that does not contain patterns susceptible to reencoding. + Therefore, protocols that offer both encryption and compression + services (e.g., SSL) need to perform the compression operation + before the encryption operation. + + $ compromise + See: data compromise, security compromise. + + $ compromise recovery + (I) The process of regaining a secure state for a system after + detecting that the system has experienced a security compromise. + + $ compromised key list (CKL) + (N) /MISSI/ A list that identifies keys for which unauthorized + disclosure or alteration may have occurred. (See: compromise.) + + Tutorial: A CKL is issued by a CA, like a CRL is issued. But a CKL + lists only KMIDs, not subjects that hold the keys, and not + certificates in which the keys are bound. + + $ COMPUSEC + (I) See: computer security. + + + + + +Shirey Informational [Page 73] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ computer emergency response team (CERT) + (I) An organization that studies computer and network INFOSEC in + order to provide incident response services to victims of attacks, + publish alerts concerning vulnerabilities and threats, and offer + other information to help improve computer and network security. + (See: CSIRT, security incident.) + + Examples: CERT Coordination Center at Carnegie Mellon University + (sometimes called "the" CERT); CIAC. + + $ Computer Incident Advisory Capability (CIAC) + (O) The centralized CSIRT of the U.S. Department of Energy; a + member of FIRST. + + $ computer network + (I) A collection of host computers together with the subnetwork or + internetwork through which they can exchange data. + + Usage: This definition is intended to cover systems of all sizes + and types, ranging from the complex Internet to a simple system + composed of a personal computer dialing in as a remote terminal of + another computer. + + $ computer platform + (I) A combination of computer hardware and an operating system + (which may consist of software, firmware, or both) for that + hardware. (Compare: computer system.) + + $ computer security (COMPUSEC) + 1. (I) Measures to implement and assure security services in a + computer system, particularly those that assure access control + service. + + Usage: Usually refers to internal controls (functions, features, + and technical characteristics) that are implemented in software + (especially in operating systems); sometimes refers to internal + controls implemented in hardware; rarely used to refer to external + controls. + + 2. (O) "The protection afforded to an automated information system + in order to attain the applicable objectives of preserving the + integrity, availability and confidentiality of information system + resources (includes hardware, software, firmware, + information/data, and telecommunications)." [SP12] + + + + + + + +Shirey Informational [Page 74] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ computer security incident response team (CSIRT) + (I) An organization "that coordinates and supports the response to + security incidents that involve sites within a defined + constituency." [R2350] (See: CERT, FIRST, security incident.) + + Tutorial: To be considered a CSIRT, an organization must do as + follows: (a) Provide a (secure) channel for receiving reports + about suspected security incidents. (b) Provide assistance to + members of its constituency in handling the incidents. (c) + Disseminate incident-related information to its constituency and + other involved parties. + + $ computer security object + (I) The definition or representation of a resource, tool, or + mechanism used to maintain a condition of security in computerized + environments. Includes many items referred to in standards that + are either selected or defined by separate user communities. + [CSOR] (See: object identifier, Computer Security Objects + Register.) + + $ Computer Security Objects Register (CSOR) + (N) A service operated by NIST is establishing a catalog for + computer security objects to provide stable object definitions + identified by unique names. The use of this register will enable + the unambiguous specification of security parameters and + algorithms to be used in secure data exchanges. (See: object + identifier.) + + Tutorial: The CSOR follows registration guidelines established by + the international standards community and ANSI. Those guidelines + establish minimum responsibilities for registration authorities + and assign the top branches of an international registration + hierarchy. Under that international registration hierarchy, the + CSOR is responsible for the allocation of unique identifiers under + the branch: {joint-iso-ccitt(2) country(16) us(840) + organization(1) gov(101) csor(3)}. + + $ computer system + (I) Synonym for "information system", or a component thereof. + (Compare: computer platform.) + + $ Computers At Risk + (O) The 1991 report [NRC91] of the System Security Study + Committee, sponsored by the U.S. National Academy of Sciences and + supported by the Defense Advanced Research Projects Agency of the + U.S. DoD. It made many recommendations for industry and + governments to improve computer security and trustworthiness. Some + of the most important recommendations (e.g., establishing an + + + +Shirey Informational [Page 75] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Information Security Foundation chartered by the U.S. Government) + have not been implemented at all, and others (e.g., codifying + Generally Accepted System Security Principles similar to + accounting principles) have been implemented but not widely + adopted [SP14, SP27]. + + $ COMSEC + (I) See: communication security. + + $ COMSEC account + (O) /U.S. Government/ "Administrative entity, identified by an + account number, used to maintain accountability, custody, and + control of COMSEC material." [C4009] (See: COMSEC custodian.) + + $ COMSEC accounting + (O) /U.S. Government/ The process of creating, collecting, and + maintaining data records that describe the status and custody of + designated items of COMSEC material. (See: accounting legend + code.) + + Tutorial: Almost any secure information system needs to record a + security audit trail, but a system that manages COMSEC material + needs to record additional data about the status and custody of + COMSEC items. + - COMSEC tracking: The process of automatically collecting, + recording, and managing information that describes the status + of designated items of COMSEC material at all times during each + product's lifecycle. + - COMSEC controlling: The process of supplementing tracking data + with custody data, which consists of explicit acknowledgements + of system entities that they (a) have received specific COMSEC + items and (b) are responsible for preventing exposure of those + items. + + For example, a key management system that serves a large customer + base needs to record tracking data for the same reasons that a + national parcel delivery system does, i.e., to answer the question + "Where is that thing now?". If keys are encrypted immediately upon + generation and handled only in BLACK form between the point of + generation and the point of use, then tracking may be all that is + needed. However, in cases where keys are handled at least partly + in RED form and are potentially subject to exposure, then tracking + needs to be supplemented by controlling. + + Data that is used purely for tracking need be retained only + temporarily, until an item's status changes. Data that is used for + controlling is retained indefinitely to ensure accountability and + support compromise recovery. + + + +Shirey Informational [Page 76] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ COMSEC boundary + (N) "Definable perimeter encompassing all hardware, firmware, and + software components performing critical COMSEC functions, such as + key generation and key handling and storage." [C4009] (Compare: + cryptographic boundary.) + + $ COMSEC custodian + (O) /U.S. Government/ "Individual designated by proper authority + to be responsible for the receipt, transfer, accounting, + safeguarding, and destruction of COMSEC material assigned to a + COMSEC account." [C4009] + + $ COMSEC material + (N) /U.S. Government/ Items designed to secure or authenticate + communications or information in general; these items include (but + are not limited to) keys; equipment, devices, documents, firmware, + and software that embodies or describes cryptographic logic; and + other items that perform COMSEC functions. [C4009] (Compare: + keying material.) + + $ COMSEC Material Control System (CMCS) + (O) /U.S. Government/ "Logistics and accounting system through + which COMSEC material marked 'CRYPTO' is distributed, controlled, + and safeguarded." [C4009] (See: COMSEC account, COMSEC custodian.) + + $ confidentiality + See: data confidentiality. + + $ concealment system + (O) "A method of achieving confidentiality in which sensitive + information is hidden by embedding it in irrelevant data." [NCS04] + (Compare: steganography.) + + $ configuration control + (I) The process of regulating changes to hardware, firmware, + software, and documentation throughout the development and + operational life of a system. (See: administrative security, + harden, trusted distribution.) + + Tutorial: Configuration control helps protect against unauthorized + or malicious alteration of a system and thus provides assurance of + system integrity. (See: malicious logic.) + + $ confinement property + (N) /formal model/ Property of a system whereby a subject has + write access to an object only if the classification of the object + dominates the clearance of the subject. (See: *-property, Bell- + LaPadula model.) + + + +Shirey Informational [Page 77] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ constraint + (I) /access control/ A limitation on the function of an identity, + role, or privilege. (See: rule-based access control.) + + Tutorial: In effect, a constraint is a form of security policy and + may be either static or dynamic: + - "Static constraint": A constraint that must be satisfied at the + time the policy is defined, and then continues to be satisfied + until the constraint is removed. + - "Dynamic constraint": A constraint that may be defined to apply + at various times that the identity, role, or other object of + the constraint is active in the system. + + $ content filter + (I) /World Wide Web/ Application software used to prevent access + to certain Web servers, such as by parents who do not want their + children to access pornography. (See: filter, guard.) + + Tutorial: The filter is usually browser-based, but could be part + of an intermediate cache server. The two basic content filtering + techniques are (a) to block a specified list of URLs and (b) to + block material that contains specified words and phrases. + + $ contingency plan + (I) A plan for emergency response, backup operations, and post- + disaster recovery in a system as part of a security program to + ensure availability of critical system resources and facilitate + continuity of operations in a crisis. [NCS04] (See: availability.) + + $ control zone + (O) "The space, expressed in feet of radius, surrounding equipment + processing sensitive information, that is under sufficient + physical and technical control to preclude an unauthorized entry + or compromise." [NCSSG] (Compare: inspectable space, TEMPEST + zone.) + + $ controlled access protection + (O) /TCSEC/ The level of evaluation criteria for a C2 computer + system. + + Tutorial: The major features of the C2 level are individual + accountability, audit, access control, and object reuse. + + $ controlled cryptographic item (CCI) + (O) /U.S. Government/ "Secure telecommunications or information + handling equipment, or associated cryptographic component, that is + unclassified but governed by a special set of control + requirements." [C4009] (Compare: EUCI.) + + + +Shirey Informational [Page 78] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Tutorial: This category of equipment was established in 1985 to + promote broad use of secure equipment for protecting both + classified and unclassified information in the national interest. + CCI equipment uses a classified cryptographic logic, but the + hardware or firmware embodiment of that logic is unclassified. + Drawings, software implementations, and other descriptions of that + logic remain classified. [N4001] + + $ controlled interface + (I) A mechanism that facilitates the adjudication of the different + security policies of interconnected systems. (See: domain, guard.) + + $ controlled security mode + (D) /U.S. DoD/ A mode of system operation wherein (a) two or more + security levels of information are allowed to be handled + concurrently within the same system when some users having access + to the system have neither a security clearance nor need-to-know + for some of the data handled by the system, but (b) separation of + the users and the classified material on the basis, respectively, + of clearance and classification level are not dependent only on + operating system control (like they are in multilevel security + mode). (See: /system operation/ under "mode", protection level.) + + Deprecated Term: IDOCs SHOULD NOT use this term. It was defined in + a U.S. Government policy regarding system accreditation and was + subsumed by "partitioned security mode" in a later policy. Both + terms were dropped in still later policies. + + Tutorial: Controlled mode was intended to encourage ingenuity in + meeting data confidentiality requirements in ways less restrictive + than "dedicated security mode" and "system-high security mode", + but at a level of risk lower than that generally associated with + true "multilevel security mode". This was intended to be + accomplished by implementation of explicit augmenting measures to + reduce or remove a substantial measure of system software + vulnerability together with specific limitation of the security + clearance levels of users having concurrent access to the system. + + $ controlling authority + (O) /U.S. Government/ "Official responsible for directing the + operation of a cryptonet and for managing the operational use and + control of keying material assigned to the cryptonet." [C4009, + N4006] + + $ cookie + 1. (I) /HTTP/ Data exchanged between an HTTP server and a browser + (a client of the server) to store state information on the client + side and retrieve it later for server use. + + + +Shirey Informational [Page 79] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Tutorial: An HTTP server, when sending data to a client, may send + along a cookie, which the client retains after the HTTP connection + closes. A server can use this mechanism to maintain persistent + client-side state information for HTTP-based applications, + retrieving the state information in later connections. A cookie + may include a description of the range of URLs for which the state + is valid. Future requests made by the client in that range will + also send the current value of the cookie to the server. Cookies + can be used to generate profiles of web usage habits, and thus may + infringe on personal privacy. + + 2. (I) /IPsec/ Data objects exchanged by ISAKMP to prevent certain + denial-of-service attacks during the establishment of a security + association. + + 3. (D) /access control/ Synonym for "capability token" or + "ticket". + + Deprecated Definition: IDOCs SHOULD NOT use this term with + definition 3; that would duplicate the meaning of better- + established terms and mix concepts in a potentially misleading + way. + + $ Coordinated Universal Time (UTC) + (N) UTC is derived from International Atomic Time (TAI) by adding + a number of leap seconds. The International Bureau of Weights and + Measures computes TAI once each month by averaging data from many + laboratories. (See: GeneralizedTime, UTCTime.) + + $ correction + (I) /security/ A system change made to eliminate or reduce the + risk of reoccurrence of a security violation or threat + consequence. (See: secondary definition under "security".) + + $ correctness + (I) "The property of a system that is guaranteed as the result of + formal verification activities." [Huff] (See: correctness proof, + verification.) + + $ correctness integrity + (I) The property that the information represented by data is + accurate and consistent. (Compare: data integrity, source + integrity.) + + Tutorial: IDOCs SHOULD NOT use this term without providing a + definition; the term is neither well-known nor precisely defined. + Data integrity refers to the constancy of data values, and source + integrity refers to confidence in data values. However, + + + +Shirey Informational [Page 80] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + correctness integrity refers to confidence in the underlying + information that data values represent, and this property is + closely related to issues of accountability and error handling. + + $ correctness proof + (I) A mathematical proof of consistency between a specification + for system security and the implementation of that specification. + (See: correctness, formal specification.) + + $ corruption + (I) A type of threat action that undesirably alters system + operation by adversely modifying system functions or data. (See: + disruption.) + + Usage: This type of threat action includes the following subtypes: + - "Tampering": /corruption/ Deliberately altering a system's + logic, data, or control information to interrupt or prevent + correct operation of system functions. (See: misuse, main entry + for "tampering".) + - "Malicious logic": /corruption/ Any hardware, firmware, or + software (e.g., a computer virus) intentionally introduced into + a system to modify system functions or data. (See: + incapacitation, main entry for "malicious logic", masquerade, + misuse.) + - "Human error": /corruption/ Human action or inaction that + unintentionally results in the alteration of system functions + or data. + - "Hardware or software error": /corruption/ Error that results + in the alteration of system functions or data. + - "Natural disaster": /corruption/ Any "act of God" (e.g., power + surge caused by lightning) that alters system functions or + data. [FP031 Section 2] + + $ counter + 1. (N) /noun/ See: counter mode. + + 2. (I) /verb/ See: countermeasure. + + $ counter-countermeasure + (I) An action, device, procedure, or technique used by an attacker + to offset a defensive countermeasure. + + Tutorial: For every countermeasure devised to protect computers + and networks, some cracker probably will be able to devise a + counter-countermeasure. Thus, systems must use "defense in depth". + + + + + + +Shirey Informational [Page 81] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ counter mode (CTR) + (N) A block cipher mode that enhances ECB mode by ensuring that + each encrypted block is different from every other block encrypted + under the same key. [SP38A] (See: block cipher.) + + Tutorial: This mode operates by first encrypting a generated + sequence of blocks, called "counters", that are separate from the + input sequence of plaintext blocks which the mode is intended to + protect. The resulting sequence of encrypted counters is + exclusive-ORed with the sequence of plaintext blocks to produce + the final ciphertext output blocks. The sequence of counters must + have the property that each counter is different from every other + counter for all of the plain text that is encrypted under the same + key. + + $ Counter with Cipher Block Chaining-Message Authentication Code + (CCM) + (N) A block cipher mode [SP38C] that provides both data + confidentiality and data origin authentication, by combining the + techniques of CTR and a CBC-based message authentication code. + (See: block cipher.) + + $ countermeasure + (I) An action, device, procedure, or technique that meets or + opposes (i.e., counters) a threat, a vulnerability, or an attack + by eliminating or preventing it, by minimizing the harm it can + cause, or by discovering and reporting it so that corrective + action can be taken. + + Tutorial: In an Internet protocol, a countermeasure may take the + form of a protocol feature, a component function, or a usage + constraint. + + $ country code + (I) An identifier that is defined for a nation by ISO. [I3166] + + Tutorial: For each nation, ISO Standard 3166 defines a unique two- + character alphabetic code, a unique three-character alphabetic + code, and a three-digit code. Among many uses of these codes, the + two-character codes are used as top-level domain names. + + $ Courtney's laws + (N) Principles for managing system security that were stated by + Robert H. Courtney, Jr. + + + + + + + +Shirey Informational [Page 82] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Tutorial: Bill Murray codified Courtney's laws as follows: [Murr] + - Courtney's first law: You cannot say anything interesting + (i.e., significant) about the security of a system except in + the context of a particular application and environment. + - Courtney's second law: Never spend more money eliminating a + security exposure than tolerating it will cost you. (See: + acceptable risk, risk analysis.) + -- First corollary: Perfect security has infinite cost. + -- Second corollary: There is no such thing as zero risk. + - Courtney's third law: There are no technical solutions to + management problems, but there are management solutions to + technical problems. + + $ covert action + (I) An operation that is planned and executed in a way that + conceals the identity of the operator. + + $ covert channel + 1. (I) An unintended or unauthorized intra-system channel that + enables two cooperating entities to transfer information in a way + that violates the system's security policy but does not exceed the + entities' access authorizations. (See: covert storage channel, + covert timing channel, out-of-band, tunnel.) + + 2. (O) "A communications channel that allows two cooperating + processes to transfer information in a manner that violates the + system's security policy." [NCS04] + + Tutorial: The cooperating entities can be either two insiders or + an insider and an outsider. Of course, an outsider has no access + authorization at all. A covert channel is a system feature that + the system architects neither designed nor intended for + information transfer. + + $ covert storage channel + (I) A system feature that enables one system entity to signal + information to another entity by directly or indirectly writing a + storage location that is later directly or indirectly read by the + second entity. (See: covert channel.) + + $ covert timing channel + (I) A system feature that enables one system entity to signal + information to another by modulating its own use of a system + resource in such a way as to affect system response time observed + by the second entity. (See: covert channel.) + + $ CPS + (I) See: certification practice statement. + + + +Shirey Informational [Page 83] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ cracker + (I) Someone who tries to break the security of, and gain + unauthorized access to, someone else's system, often with + malicious intent. (See: adversary, intruder, packet monkey, script + kiddy. Compare: hacker.) + + Usage: Was sometimes spelled "kracker". [NCSSG] + + $ CRAM + (I) See: Challenge-Response Authentication Mechanism. + + $ CRC + (I) See: cyclic redundancy check. + + $ credential + 1. (I) /authentication/ "identifier credential": A data object + that is a portable representation of the association between an + identifier and a unit of authentication information, and that can + be presented for use in verifying an identity claimed by an entity + that attempts to access a system. Example: X.509 public-key + certificate. (See: anonymous credential.) + + 2. (I) /access control/ "authorization credential": A data object + that is a portable representation of the association between an + identifier and one or more access authorizations, and that can be + presented for use in verifying those authorizations for an entity + that attempts such access. Example: X.509 attribute certificate. + (See: capability token, ticket.) + + 3. (D) /OSIRM/ "Data that is transferred to establish the claimed + identity of an entity." [I7498-2] + + Deprecated Definition: IDOCs SHOULD NOT use the term with + definition 3. As explained in the tutorial below, an + authentication process can involve the transfer of multiple data + objects, and not all of those are credentials. + + 4. (D) /U.S. Government/ "An object that is verified when + presented to the verifier in an authentication transaction." + [M0404] + + Deprecated Definition: IDOCs SHOULD NOT use the term with + definition 4; it mixes concepts in a potentially misleading way. + For example, in an authentication process, it is the identity that + is "verified", not the credential; the credential is "validated". + (See: validate vs. verify.) + + + + + +Shirey Informational [Page 84] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Tutorial: In general English, "credentials" are evidence or + testimonials that (a) support a claim of identity or authorization + and (b) usually are intended to be used more than once (i.e., a + credential's life is long compared to the time needed for one + use). Some examples are a policeman's badge, an automobile + driver's license, and a national passport. An authentication or + access control process that uses a badge, license, or passport is + outwardly simple: the holder just shows the thing. + + The problem with adopting this term in Internet security is that + an automated process for authentication or access control usually + requires multiple steps using multiple data objects, and it might + not be immediately obvious which of those objects should get the + name "credential". + + For example, if the verification step in a user authentication + process employs public-key technology, then the process involves + at least three data items: (a) the user's private key, (b) a + signed value -- signed with that private key and passed to the + system, perhaps in response to a challenge from the system -- and + (c) the user's public-key certificate, which is validated by the + system and provides the public key needed to verify the signature. + - Private key: The private key is *not* a credential, because it + is never transferred or presented. Instead, the private key is + "authentication information", which is associated with the + user's identifier for a specified period of time and can be + used in multiple authentications during that time. + - Signed value: The signed value is *not* a credential; the + signed value is only ephemeral, not long lasting. The OSIRM + definition could be interpreted to call the signed value a + credential, but that would conflict with general English. + - Certificate: The user's certificate *is* a credential. It can + be "transferred" or "presented" to any person or process that + needs it at any time. A public-key certificate may be used as + an "identity credential", and an attribute certificate may be + used as an "authorization credential". + + $ critical + 1. (I) /system resource/ A condition of a system resource such + that denial of access to, or lack of availability of, that + resource would jeopardize a system user's ability to perform a + primary function or would result in other serious consequences, + such as human injury or loss of life. (See: availability, + precedence. Compare: sensitive.) + + 2. (N) /extension/ An indication that an application is not + permitted to ignore an extension. [X509] + + + + +Shirey Informational [Page 85] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Tutorial: Each extension of an X.509 certificate or CRL is flagged + as either "critical" or "non-critical". In a certificate, if a + computer program does not recognize an extension's type (i.e., + does not implement its semantics), then if the extension is + critical, the program is required to treat the certificate as + invalid; but if the extension is non-critical, the program is + permitted to ignore the extension. + + In a CRL, if a program does not recognize a critical extension + that is associated with a specific certificate, the program is + required to assume that the listed certificate has been revoked + and is no longer valid, and then take whatever action is required + by local policy. + + When a program does not recognize a critical extension that is + associated with the CRL as a whole, the program is required to + assume that all listed certificates have been revoked and are no + longer valid. However, since failing to process the extension may + mean that the list has not been completed, the program cannot + assume that other certificates are valid, and the program needs to + take whatever action is therefore required by local policy. + + $ critical information infrastructure + (I) Those systems that are so vital to a nation that their + incapacity or destruction would have a debilitating effect on + national security, the economy, or public health and safety. + + $ CRL + (I) See: certificate revocation list. + + $ CRL distribution point + (I) See: distribution point. + + $ CRL extension + (I) See: extension. + + $ cross-certificate + (I) A public-key certificate issued by a CA in one PKI to a CA in + another PKI. (See: cross-certification.) + + $ cross-certification + (I) The act or process by which a CA in one PKI issues a public- + key certificate to a CA in another PKI. [X509] (See: bridge CA.) + + Tutorial: X.509 says that a CA (say, CA1) may issue a "cross- + certificate" in which the subject is another CA (say, CA2). X.509 + calls CA2 the "subject CA" and calls CA1 an "intermediate CA", but + + + + +Shirey Informational [Page 86] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + this Glossary deprecates those terms. (See: intermediate CA, + subject CA). + + Cross-certification of CA2 by CA1 appears similar to certification + of a subordinate CA by a superior CA, but cross-certification + involves a different concept. The "subordinate CA" concept applies + when both CAs are in the same PKI, i.e., when either (a) CA1 and + CA2 are under the same root or (b) CA1 is itself a root. The + "cross-certification" concept applies in other cases: + + First, cross-certification applies when two CAs are in different + PKIs, i.e., when CA1 and CA2 are under different roots, or perhaps + are both roots themselves. Issuing the cross-certificate enables + end entities certified under CA1 in PK1 to construct the + certification paths needed to validate the certificates of end + entities certified under CA2 in PKI2. Sometimes, a pair of cross- + certificates is issued -- by CA1 to CA2, and by CA2 to CA1 -- so + that an end entity in either PKI can validate certificates issued + in the other PKI. + + Second, X.509 says that two CAs in some complex, multi-CA PKI can + cross-certify one another to shorten the certification paths + constructed by end entities. Whether or not a CA may perform this + or any other form of cross-certification, and how such + certificates may be used by end entities, should be addressed by + the local certificate policy and CPS. + + $ cross-domain solution + 1. (D) Synonym for "guard". + + Deprecated Term: IDOCs SHOULD NOT use this term as a synonym for + "guard"; this term unnecessarily (and verbosely) duplicates the + meaning of the long-established "guard". + + 2. (O) /U.S. Government/ A process or subsystem that provides a + capability (which could be either manual or automated) to access + two or more differing security domains in a system, or to transfer + information between such domains. (See: domain, guard.) + + $ cryptanalysis + 1. (I) The mathematical science that deals with analysis of a + cryptographic system to gain knowledge needed to break or + circumvent the protection that the system is designed to provide. + (See: cryptology, secondary definition under "intrusion".) + + 2. (O) "The analysis of a cryptographic system and/or its inputs + and outputs to derive confidential variables and/or sensitive data + including cleartext." [I7498-2] + + + +Shirey Informational [Page 87] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Tutorial: Definition 2 states the traditional goal of + cryptanalysis, i.e., convert cipher text to plain text (which + usually is clear text) without knowing the key; but that + definition applies only to encryption systems. Today, the term is + used with reference to all kinds of cryptographic algorithms and + key management, and definition 1 reflects that. In all cases, + however, a cryptanalyst tries to uncover or reproduce someone + else's sensitive data, such as clear text, a key, or an algorithm. + The basic cryptanalytic attacks on encryption systems are + ciphertext-only, known-plaintext, chosen-plaintext, and chosen- + ciphertext; and these generalize to the other kinds of + cryptography. + + $ crypto, CRYPTO + 1. (N) A prefix ("crypto-") that means "cryptographic". + + Usage: IDOCs MAY use this prefix when it is part of a term listed + in this Glossary. Otherwise, IDOCs SHOULD NOT use this prefix; + instead, use the unabbreviated adjective, "cryptographic". + + 2. (D) In lower case, "crypto" is an abbreviation for the + adjective "cryptographic", or for the nouns "cryptography" or + "cryptographic component". + + Deprecated Abbreviation: IDOCs SHOULD NOT use this abbreviation + because it could easily be misunderstood in some technical sense. + + 3. (O) /U.S. Government/ In upper case, "CRYPTO" is a marking or + designator that identifies "COMSEC keying material used to secure + or authenticate telecommunications carrying classified or + sensitive U.S. Government or U.S. Government-derived information." + [C4009] (See: security label, security marking.) + + $ cryptographic + (I) An adjective that refers to cryptography. + + $ cryptographic algorithm + (I) An algorithm that uses the science of cryptography, including + (a) encryption algorithms, (b) cryptographic hash algorithms, (c) + digital signature algorithms, and (d) key-agreement algorithms. + + $ cryptographic application programming interface (CAPI) + (I) The source code formats and procedures through which an + application program accesses cryptographic services, which are + defined abstractly compared to their actual implementation. + Example, see: PKCS #11, [R2628]. + + + + + +Shirey Informational [Page 88] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ cryptographic association + (I) A security association that involves the use of cryptography + to provide security services for data exchanged by the associated + entities. (See: ISAKMP.) + + $ cryptographic boundary + (I) See: secondary definition under "cryptographic module". + + $ cryptographic card + (I) A cryptographic token in the form of a smart card or a PC + card. + + $ cryptographic component + (I) A generic term for any system component that involves + cryptography. (See: cryptographic module.) + + $ cryptographic hash + (I) See: secondary definition under "hash function". + + $ cryptographic ignition key (CIK) + 1. (N) A physical (usually electronic) token used to store, + transport, and protect cryptographic keys and activation data. + (Compare: dongle, fill device.) + + Tutorial: A key-encrypting key could be divided (see: split key) + between a CIK and a cryptographic module, so that it would be + necessary to combine the two to regenerate the key, use it to + decrypt other keys and data contained in the module, and thus + activate the module. + + 2. (O) "Device or electronic key used to unlock the secure mode of + cryptographic equipment." [C4009] Usage: Abbreviated as "crypto- + ignition key". + + $ cryptographic key + (I) See: key. Usage: Usually shortened to just "key". + + $ Cryptographic Message Syntax (CMS) + (I) An encapsulation syntax (RFC 3852) for digital signatures, + hashes, and encryption of arbitrary messages. + + Tutorial: CMS derives from PKCS #7. CMS values are specified with + ASN.1 and use BER encoding. The syntax permits multiple + encapsulation with nesting, permits arbitrary attributes to be + signed along with message content, and supports a variety of + architectures for digital certificate-based key management. + + + + + +Shirey Informational [Page 89] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ cryptographic module + (I) A set of hardware, software, firmware, or some combination + thereof that implements cryptographic logic or processes, + including cryptographic algorithms, and is contained within the + module's "cryptographic boundary", which is an explicitly defined + contiguous perimeter that establishes the physical bounds of the + module. [FP140] + + $ cryptographic system + 1. (I) A set of cryptographic algorithms together with the key + management processes that support use of the algorithms in some + application context. + + Usage: IDOCs SHOULD use definition 1 because it covers a wider + range of algorithms than definition 2. + + 2. (O) "A collection of transformations from plain text into + cipher text and vice versa [which would exclude digital signature, + cryptographic hash, and key-agreement algorithms], the particular + transformation(s) to be used being selected by keys. The + transformations are normally defined by a mathematical algorithm." + [X509] + + $ cryptographic token + 1. (I) A portable, user-controlled, physical device (e.g., smart + card or PCMCIA card) used to store cryptographic information and + possibly also perform cryptographic functions. (See: cryptographic + card, token.) + + Tutorial: A smart token might implement some set of cryptographic + algorithms and might incorporate related key management functions, + such as a random number generator. A smart cryptographic token may + contain a cryptographic module or may not be explicitly designed + that way. + + $ cryptography + 1. (I) The mathematical science that deals with transforming data + to render its meaning unintelligible (i.e., to hide its semantic + content), prevent its undetected alteration, or prevent its + unauthorized use. If the transformation is reversible, + cryptography also deals with restoring encrypted data to + intelligible form. (See: cryptology, steganography.) + + 2. (O) "The discipline which embodies principles, means, and + methods for the transformation of data in order to hide its + information content, prevent its undetected modification and/or + prevent its unauthorized use.... Cryptography determines the + methods used in encipherment and decipherment." [I7498-2] + + + +Shirey Informational [Page 90] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Tutorial: Comprehensive coverage of applied cryptographic + protocols and algorithms is provided by Schneier [Schn]. + Businesses and governments use cryptography to make data + incomprehensible to outsiders; to make data incomprehensible to + both outsiders and insiders, the data is sent to lawyers for a + rewrite. + + $ Cryptoki + (N) A CAPI defined in PKCS #11. Pronunciation: "CRYPTO-key". + Derivation: Abbreviation of "cryptographic token interface". + + $ cryptology + (I) The science of secret communication, which includes both + cryptography and cryptanalysis. + + Tutorial: Sometimes the term is used more broadly to denote + activity that includes both rendering signals secure (see: signal + security) and extracting information from signals (see: signal + intelligence) [Kahn]. + + $ cryptonet + (I) A network (i.e., a communicating set) of system entities that + share a secret cryptographic key for a symmetric algorithm. (See: + controlling authority.) + + (O) "Stations holding a common key." [C4009] + + $ cryptoperiod + (I) The time span during which a particular key value is + authorized to be used in a cryptographic system. (See: key + management.) + + Usage: This term is long-established in COMPUSEC usage. In the + context of certificates and public keys, "key lifetime" and + "validity period" are often used instead. + + Tutorial: A cryptoperiod is usually stated in terms of calendar or + clock time, but sometimes is stated in terms of the maximum amount + of data permitted to be processed by a cryptographic algorithm + using the key. Specifying a cryptoperiod involves a tradeoff + between the cost of rekeying and the risk of successful + cryptoanalysis. + + $ cryptosystem + (I) Contraction of "cryptographic system". + + $ cryptovariable + (D) Synonym for "key". + + + +Shirey Informational [Page 91] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Deprecated Usage: In contemporary COMSEC usage, the term "key" has + replaced the term "cryptovariable". + + $ CSIRT + (I) See: computer security incident response team. + + $ CSOR + (N) See: Computer Security Objects Register. + + $ CTAK + (D) See: ciphertext auto-key. + + $ CTR + (N) See: counter mode. + + $ cut-and-paste attack + (I) An active attack on the data integrity of cipher text, + effected by replacing sections of cipher text with other cipher + text, such that the result appears to decrypt correctly but + actually decrypts to plain text that is forged to the satisfaction + of the attacker. + + $ cyclic redundancy check (CRC) + (I) A type of checksum algorithm that is not a cryptographic hash + but is used to implement data integrity service where accidental + changes to data are expected. Sometimes called "cyclic redundancy + code". + + $ DAC + (N) See: Data Authentication Code, discretionary access control. + + Deprecated Usage: IDOCs that use this term SHOULD state a + definition for it because this abbreviation is ambiguous. + + $ daemon + (I) A computer program that is not invoked explicitly but waits + until a specified condition occurs, and then runs with no + associated user (principal), usually for an administrative + purpose. (See: zombie.) + + $ dangling threat + (O) A threat to a system for which there is no corresponding + vulnerability and, therefore, no implied risk. + + $ dangling vulnerability + (O) A vulnerability of a system for which there is no + corresponding threat and, therefore, no implied risk. + + + + +Shirey Informational [Page 92] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ DASS + (I) See: Distributed Authentication Security Service. + + $ data + (I) Information in a specific representation, usually as a + sequence of symbols that have meaning. + + Usage: Refers to both (a) representations that can be recognized, + processed, or produced by a computer or other type of machine, and + (b) representations that can be handled by a human. + + $ Data Authentication Algorithm, data authentication algorithm + 1. (N) /capitalized/ The ANSI standard for a keyed hash function + that is equivalent to DES cipher block chaining with IV = 0. + [A9009] + + 2. (D) /not capitalized/ Synonym for some kind of "checksum". + + Deprecated Term: IDOCs SHOULD NOT use the uncapitalized form "data + authentication algorithm" as a synonym for any kind of checksum, + regardless of whether or not the checksum is based on a hash. + Instead, use "checksum", "Data Authentication Code", "error + detection code", "hash", "keyed hash", "Message Authentication + Code", "protected checksum", or some other specific term, + depending on what is meant. + + The uncapitalized term can be confused with the Data + Authentication Code and also mixes concepts in a potentially + misleading way. The word "authentication" is misleading because + the checksum may be used to perform a data integrity function + rather than a data origin authentication function. + + $ Data Authentication Code, data authentication code + 1. (N) /capitalized/ A specific U.S. Government standard [FP113] + for a checksum that is computed by the Data Authentication + Algorithm. Usage: a.k.a. Message Authentication Code [A9009].) + (See: DAC.) + + 2. (D) /not capitalized/ Synonym for some kind of "checksum". + + Deprecated Term: IDOCs SHOULD NOT use the uncapitalized form "data + authentication code" as a synonym for any kind of checksum, + regardless of whether or not the checksum is based on the Data + Authentication Algorithm. The uncapitalized term can be confused + with the Data Authentication Code and also mixes concepts in a + potentially misleading way (see: authentication code). + + + + + +Shirey Informational [Page 93] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ data compromise + 1. (I) A security incident in which information is exposed to + potential unauthorized access, such that unauthorized disclosure, + alteration, or use of the information might have occurred. + (Compare: security compromise, security incident.) + + 2. (O) /U.S. DoD/ A "compromise" is a "communication or physical + transfer of information to an unauthorized recipient." [DoD5] + + 3. (O) /U.S. Government/ "Type of [security] incident where + information is disclosed to unauthorized individuals or a + violation of the security policy of a system in which unauthorized + intentional or unintentional disclosure, modification, + destruction, or loss of an object may have occurred." [C4009] + + $ data confidentiality + 1. (I) The property that data is not disclosed to system entities + unless they have been authorized to know the data. (See: Bell- + LaPadula model, classification, data confidentiality service, + secret. Compare: privacy.) + + 2. (D) "The property that information is not made available or + disclosed to unauthorized individuals, entities, or processes + [i.e., to any unauthorized system entity]." [I7498-2]. + + Deprecated Definition: The phrase "made available" might be + interpreted to mean that the data could be altered, and that would + confuse this term with the concept of "data integrity". + + $ data confidentiality service + (I) A security service that protects data against unauthorized + disclosure. (See: access control, data confidentiality, datagram + confidentiality service, flow control, inference control.) + + Deprecated Usage: IDOCs SHOULD NOT use this term as a synonym for + "privacy", which is a different concept. + + $ Data Encryption Algorithm (DEA) + (N) A symmetric block cipher, defined in the U.S. Government's + DES. DEA uses a 64-bit key, of which 56 bits are independently + chosen and 8 are parity bits, and maps a 64-bit block into another + 64-bit block. [FP046] (See: AES, symmetric cryptography.) + + Usage: This algorithm is usually referred to as "DES". The + algorithm has also been adopted in standards outside the + Government (e.g., [A3092]). + + + + + +Shirey Informational [Page 94] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ data encryption key (DEK) + (I) A cryptographic key that is used to encipher application data. + (Compare: key-encrypting key.) + + $ Data Encryption Standard (DES) + (N) A U.S. Government standard [FP046] that specifies the DEA and + states policy for using the algorithm to protect unclassified, + sensitive data. (See: AES.) + + $ data integrity + 1. (I) The property that data has not been changed, destroyed, or + lost in an unauthorized or accidental manner. (See: data integrity + service. Compare: correctness integrity, source integrity.) + + 2. (O) "The property that information has not been modified or + destroyed in an unauthorized manner." [I7498-2] + + Usage: Deals with (a) constancy of and confidence in data values, + and not with either (b) information that the values represent + (see: correctness integrity) or (c) the trustworthiness of the + source of the values (see: source integrity). + + $ data integrity service + (I) A security service that protects against unauthorized changes + to data, including both intentional change or destruction and + accidental change or loss, by ensuring that changes to data are + detectable. (See: data integrity, checksum, datagram integrity + service.) + + Tutorial: A data integrity service can only detect a change and + report it to an appropriate system entity; changes cannot be + prevented unless the system is perfect (error-free) and no + malicious user has access. However, a system that offers data + integrity service might also attempt to correct and recover from + changes. + + The ability of this service to detect changes is limited by the + technology of the mechanisms used to implement the service. For + example, if the mechanism were a one-bit parity check across each + entire SDU, then changes to an odd number of bits in an SDU would + be detected, but changes to an even number of bits would not. + + Relationship between data integrity service and authentication + services: Although data integrity service is defined separately + from data origin authentication service and peer entity + authentication service, it is closely related to them. + Authentication services depend, by definition, on companion data + integrity services. Data origin authentication service provides + + + +Shirey Informational [Page 95] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + verification that the identity of the original source of a + received data unit is as claimed; there can be no such + verification if the data unit has been altered. Peer entity + authentication service provides verification that the identity of + a peer entity in a current association is as claimed; there can be + no such verification if the claimed identity has been altered. + + $ data origin authentication + (I) "The corroboration that the source of data received is as + claimed." [I7498-2] (See: authentication.) + + $ data origin authentication service + (I) A security service that verifies the identity of a system + entity that is claimed to be the original source of received data. + (See: authentication, authentication service.) + + Tutorial: This service is provided to any system entity that + receives or holds the data. Unlike peer entity authentication + service, this service is independent of any association between + the originator and the recipient, and the data in question may + have originated at any time in the past. + + A digital signature mechanism can be used to provide this service, + because someone who does not know the private key cannot forge the + correct signature. However, by using the signer's public key, + anyone can verify the origin of correctly signed data. + + This service is usually bundled with connectionless data integrity + service. (See: "relationship between data integrity service and + authentication services" under "data integrity service". + + $ data owner + (N) The organization that has the final statutory and operational + authority for specified information. + + $ data privacy + (D) Synonym for "data confidentiality". + + Deprecated Term: IDOCs SHOULD NOT use this term; it mixes concepts + in a potentially misleading way. Instead, use either "data + confidentiality" or "privacy" or both, depending on what is meant. + + $ data recovery + 1. (I) /cryptanalysis/ A process for learning, from some cipher + text, the plain text that was previously encrypted to produce the + cipher text. (See: recovery.) + + + + + +Shirey Informational [Page 96] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + 2. (I) /system integrity/ The process of restoring information + following damage or destruction. + + $ data security + (I) The protection of data from disclosure, alteration, + destruction, or loss that either is accidental or is intentional + but unauthorized. + + Tutorial: Both data confidentiality service and data integrity + service are needed to achieve data security. + + $ datagram + (I) "A self-contained, independent entity of data [i.e., a packet] + carrying sufficient information to be routed from the source + [computer] to the destination computer without reliance on earlier + exchanges between this source and destination computer and the + transporting network." [R1983] Example: A PDU of IP. + + $ datagram confidentiality service + (I) A data confidentiality service that preserves the + confidentiality of data in a single, independent, packet; i.e., + the service applies to datagrams one-at-a-time. Example: ESP. + (See: data confidentiality.) + + Usage: When a protocol is said to provide data confidentiality + service, this is usually understood to mean that only the SDU is + protected in each packet. IDOCs that use the term to mean that the + entire PDU is protected should include a highlighted definition. + + Tutorial: This basic form of network confidentiality service + suffices for protecting the data in a stream of packets in both + connectionless and connection-oriented protocols. Except perhaps + for traffic flow confidentiality, nothing further is needed to + protect the confidentiality of data carried by a packet stream. + The OSIRM distinguishes between connection confidentiality and + connectionless confidentiality. The IPS need not make that + distinction, because those services are just instances of the same + service (i.e., datagram confidentiality) being offered in two + different protocol contexts. (For data integrity service, however, + additional effort is needed to protect a stream, and the IPS does + need to distinguish between "datagram integrity service" and + "stream integrity service".) + + $ datagram integrity service + (I) A data integrity service that preserves the integrity of data + in a single, independent, packet; i.e., the service applies to + datagrams one-at-a-time. (See: data integrity. Compare: stream + integrity service.) + + + +Shirey Informational [Page 97] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Tutorial: The ability to provide appropriate data integrity is + important in many Internet security situations, and so there are + different kinds of data integrity services suited to different + applications. This service is the simplest kind; it is suitable + for connectionless data transfers. + + Datagram integrity service usually is designed only to attempt to + detect changes to the SDU in each packet, but it might also + attempt to detect changes to some or all of the PCI in each packet + (see: selective field integrity). In contrast to this simple, + one-at-a-time service, some security situations demand a more + complex service that also attempts to detect deleted, inserted, or + reordered datagrams within a stream of datagrams (see: stream + integrity service). + + $ DEA + (N) See: Data Encryption Algorithm. + + $ deception + (I) A circumstance or event that may result in an authorized + entity receiving false data and believing it to be true. (See: + authentication.) + + Tutorial: This is a type of threat consequence, and it can be + caused by the following types of threat actions: masquerade, + falsification, and repudiation. + + $ decipher + (D) Synonym for "decrypt". + + Deprecated Definition: IDOCs SHOULD NOT use this term as a synonym + for "decrypt". However, see usage note under "encryption". + + $ decipherment + (D) Synonym for "decryption". + + Deprecated Definition: IDOCs SHOULD NOT use this term as a synonym + for "decryption". However, see the Usage note under "encryption". + + $ declassification + (I) An authorized process by which information is declassified. + (Compare: classification.) + + $ declassify + (I) To officially remove the security level designation of a + classified information item or information type, such that the + information is no longer classified (i.e., becomes unclassified). + (See: classified, classify, security level. Compare: downgrade.) + + + +Shirey Informational [Page 98] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ decode + 1. (I) Convert encoded data back to its original form of + representation. (Compare: decrypt.) + + 2. (D) Synonym for "decrypt". + + Deprecated Definition: Encoding is not usually meant to conceal + meaning. Therefore, IDOCs SHOULD NOT use this term as a synonym + for "decrypt", because that would mix concepts in a potentially + misleading way. + + $ decrypt + (I) Cryptographically restore cipher text to the plaintext form it + had before encryption. + + $ decryption + (I) See: secondary definition under "encryption". + + $ dedicated security mode + (I) A mode of system operation wherein all users having access to + the system possess, for all data handled by the system, both (a) + all necessary authorizations (i.e., security clearance and formal + access approval) and (b) a need-to-know. (See: /system operation/ + under "mode", formal access approval, need to know, protection + level, security clearance.) + + Usage: Usually abbreviated as "dedicated mode". This mode was + defined in U.S. Government policy on system accreditation, but the + term is also used outside the Government. In this mode, the system + may handle either (a) a single classification level or category of + information or (b) a range of levels and categories. + + $ default account + (I) A system login account (usually accessed with a user + identifier and password) that has been predefined in a + manufactured system to permit initial access when the system is + first put into service. (See: harden.) + + Tutorial: A default account becomes a serious vulnerability if not + properly administered. Sometimes, the default identifier and + password are well-known because they are the same in each copy of + the system. In any case, when a system is put into service, any + default password should immediately be changed or the default + account should be disabled. + + $ defense in depth + (N) "The siting of mutually supporting defense positions designed + to absorb and progressively weaken attack, prevent initial + + + +Shirey Informational [Page 99] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + observations of the whole position by the enemy, and [enable] the + commander to maneuver the reserve." [JP1] + + Tutorial: In information systems, defense in depth means + constructing a system's security architecture with layered and + complementary security mechanisms and countermeasures, so that if + one security mechanism is defeated, one or more other mechanisms + (which are "behind" or "beneath" the first mechanism) still + provide protection. + + This architectural concept is appealing because it aligns with + traditional warfare doctrine, which applies defense in depth to + physical, geospatial structures; but applying the concept to + logical, cyberspace structures of computer networks is more + difficult. The concept assumes that networks have a spatial or + topological representation. It also assumes that there can be + implemented -- from the "outer perimeter" of a network, through + its various "layers" of components, to its "center" (i.e., to the + subscriber application systems supported by the network) -- a + varied series of countermeasures that together provide adequate + protection. However, it is more difficult to map the topology of + networks and make certain that no path exists by which an attacker + could bypass all defensive layers. + + $ Defense Information Infrastructure (DII) + (O) /U.S. DoD/ The U.S. DoD's shared, interconnected system of + computers, communications, data, applications, security, people, + training, and support structures, serving information needs + worldwide. (See: DISN.) Usage: Has evolved to be called the GIG. + + Tutorial: The DII connects mission support, command and control, + and intelligence computers and users through voice, data, imagery, + video, and multimedia services, and provides information + processing and value-added services to subscribers over the DISN. + Users' own data and application software are not considered part + of the DII. + + $ Defense Information Systems Network (DISN) + (O) /U.S. DoD/ The U.S. DoD's consolidated, worldwide, enterprise + level telecommunications infrastructure that provides end-to-end + information transfer for supporting military operations; a part of + the DII. (Compare: GIG.) + + $ degauss + 1a. (N) Apply a magnetic field to permanently remove data from a + magnetic storage medium, such as a tape or disk [NCS25]. (Compare: + erase, purge, sanitize.) + + + + +Shirey Informational [Page 100] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + 1b. (N) Reduce magnetic flux density to zero by applying a + reversing magnetic field. (See: magnetic remanence.) + + $ degausser + (N) An electrical device that can degauss magnetic storage media. + + $ DEK + (I) See: data encryption key. + + $ delay + (I) /packet/ See: secondary definition under "stream integrity + service". + + $ deletion + (I) /packet/ See: secondary definition under "stream integrity + service". + + $ deliberate exposure + (I) /threat action/ See: secondary definition under "exposure". + + $ delta CRL + (I) A partial CRL that only contains entries for certificates that + have been revoked since the issuance of a prior, base CRL [X509]. + This method can be used to partition CRLs that become too large + and unwieldy. (Compare: CRL distribution point.) + + $ demilitarized zone (DMZ) + (D) Synonym for "buffer zone". + + Deprecated Term: IDOCs SHOULD NOT use this term because it mixes + concepts in a potentially misleading way. (See: Deprecated Usage + under "Green Book".) + + $ denial of service + (I) The prevention of authorized access to a system resource or + the delaying of system operations and functions. (See: + availability, critical, flooding.) + + Tutorial: A denial-of-service attack can prevent the normal + conduct of business on the Internet. There are four types of + solutions to this security problem: + - Awareness: Maintaining cognizance of security threats and + vulnerabilities. (See: CERT.) + - Detection: Finding attacks on end systems and subnetworks. + (See: intrusion detection.) + - Prevention: Following defensive practices on network-connected + systems. (See: [R2827].) + + + + +Shirey Informational [Page 101] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + - Response: Reacting effectively when attacks occur. (See: CSIRT, + contingency plan.) + + $ DES + (N) See: Data Encryption Standard. + + $ designated approving authority (DAA) + (O) /U.S. Government/ Synonym for "accreditor". + + $ detection + (I) See: secondary definition under "security". + + $ deterrence + (I) See: secondary definition under "security". + + $ dictionary attack + (I) An attack that uses a brute-force technique of successively + trying all the words in some large, exhaustive list. + + Examples: Attack an authentication service by trying all possible + passwords. Attack an encryption service by encrypting some known + plaintext phrase with all possible keys so that the key for any + given encrypted message containing that phrase may be obtained by + lookup. + + $ Diffie-Hellman + $ Diffie-Hellman-Merkle + (N) A key-agreement algorithm published in 1976 by Whitfield + Diffie and Martin Hellman [DH76, R2631]. + + Usage: The algorithm is most often called "Diffie-Hellman". + However, in the November 1978 issue of "IEEE Communications + Magazine", Hellman wrote that the algorithm "is a public key + distribution system, a concept developed by [Ralph C.] Merkle, and + hence should be called 'Diffie-Hellman-Merkle' ... to recognize + Merkle's equal contribution to the invention of public key + cryptography." + + Tutorial: Diffie-Hellman-Merkle does key establishment, not + encryption. However, the key that it produces may be used for + encryption, for further key management operations, or for any + other cryptography. + + The algorithm is described in [R2631] and [Schn]. In brief, Alice + and Bob together pick large integers that satisfy certain + mathematical conditions, and then use the integers to each + separately compute a public-private key pair. They send each other + their public key. Each person uses their own private key and the + + + +Shirey Informational [Page 102] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + other person's public key to compute a key, k, that, because of + the mathematics of the algorithm, is the same for each of them. + Passive wiretapping cannot learn the shared k, because k is not + transmitted, and neither are the private keys needed to compute k. + + The difficulty of breaking Diffie-Hellman-Merkle is considered to + be equal to the difficulty of computing discrete logarithms modulo + a large prime. However, without additional mechanisms to + authenticate each party to the other, a protocol based on the + algorithm may be vulnerable to a man-in-the-middle attack. + + $ digest + See: message digest. + + $ digital certificate + (I) A certificate document in the form of a digital data object (a + data object used by a computer) to which is appended a computed + digital signature value that depends on the data object. (See: + attribute certificate, public-key certificate.) + + Deprecated Usage: IDOCs SHOULD NOT use this term to refer to a + signed CRL or CKL. Although the recommended definition can be + interpreted to include other signed items, the security community + does not use the term with those meanings. + + $ digital certification + (D) Synonym for "certification". + + Deprecated Definition: IDOCs SHOULD NOT use this definition unless + the context is not sufficient to distinguish between digital + certification and another kind of certification, in which case it + would be better to use "public-key certification" or another + phrase that indicates what is being certified. + + $ digital document + (I) An electronic data object that represents information + originally written in a non-electronic, non-magnetic medium + (usually ink on paper) or is an analogue of a document of that + type. + + $ digital envelope + (I) A combination of (a) encrypted content data (of any kind) + intended for a recipient and (b) the content encryption key in an + encrypted form that has been prepared for the use of the + recipient. + + + + + + +Shirey Informational [Page 103] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Usage: In IDOCs, the term SHOULD be defined at the point of first + use because, although the term is defined in PKCS #7 and used in + S/MIME, it is not widely known. + + Tutorial: Digital enveloping is not simply a synonym for + implementing data confidentiality with encryption; digital + enveloping is a hybrid encryption scheme to "seal" a message or + other data, by encrypting the data and sending both it and a + protected form of the key to the intended recipient, so that no + one other than the intended recipient can "open" the message. In + PKCS #7, it means first encrypting the data using a symmetric + encryption algorithm and a secret key, and then encrypting the + secret key using an asymmetric encryption algorithm and the public + key of the intended recipient. In S/MIME, additional methods are + defined for encrypting the content encryption key. + + $ Digital ID(service mark) + (D) Synonym for "digital certificate". + + Deprecated Term: IDOCs SHOULD NOT use this term. It is a service + mark of a commercial firm, and it unnecessarily duplicates the + meaning of a better-established term. (See: credential.) + + $ digital key + (D) Synonym for an input parameter of a cryptographic algorithm or + other process. (See: key.) + + Deprecated Usage: The adjective "digital" need not be used with + "key" or "cryptographic key", unless the context is insufficient + to distinguish the digital key from another kind of key, such as a + metal key for a door lock. + + $ digital notary + (I) An electronic functionary analogous to a notary public. + Provides a trusted timestamp for a digital document, so that + someone can later prove that the document existed at that point in + time; verifies the signature(s) on a signed document before + applying the stamp. (See: notarization.) + + $ digital signature + 1. (I) A value computed with a cryptographic algorithm and + associated with a data object in such a way that any recipient of + the data can use the signature to verify the data's origin and + integrity. (See: data origin authentication service, data + integrity service, signer. Compare: digitized signature, + electronic signature.) + + + + + +Shirey Informational [Page 104] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + 2. (O) "Data appended to, or a cryptographic transformation of, a + data unit that allows a recipient of the data unit to prove the + source and integrity of the data unit and protect against forgery, + e.g. by the recipient." [I7498-2] + + Tutorial: A digital signature should have these properties: + - Be capable of being verified. (See: validate vs. verify.) + - Be bound to the signed data object in such a way that if the + data is changed, then when an attempt is made to verify the + signature, it will be seen as not authentic. (In some schemes, + the signature is appended to the signed object as stated by + definition 2, but in other it, schemes is not.) + - Uniquely identify a system entity as being the signer. + - Be under the signer's sole control, so that it cannot be + created by any other entity. + + To achieve these properties, the data object is first input to a + hash function, and then the hash result is cryptographically + transformed using a private key of the signer. The final resulting + value is called the digital signature of the data object. The + signature value is a protected checksum, because the properties of + a cryptographic hash ensure that if the data object is changed, + the digital signature will no longer match it. The digital + signature is unforgeable because one cannot be certain of + correctly creating or changing the signature without knowing the + private key of the supposed signer. + + Some digital signature schemes use an asymmetric encryption + algorithm (e.g., "RSA") to transform the hash result. Thus, when + Alice needs to sign a message to send to Bob, she can use her + private key to encrypt the hash result. Bob receives both the + message and the digital signature. Bob can use Alice's public key + to decrypt the signature, and then compare the plaintext result to + the hash result that he computes by hashing the message himself. + If the values are equal, Bob accepts the message because he is + certain that it is from Alice and has arrived unchanged. If the + values are not equal, Bob rejects the message because either the + message or the signature was altered in transit. + + Other digital signature schemes (e.g., "DSS") transform the hash + result with an algorithm (e.g., "DSA", "El Gamal") that cannot be + directly used to encrypt data. Such a scheme creates a signature + value from the hash and provides a way to verify the signature + value, but does not provide a way to recover the hash result from + the signature value. In some countries, such a scheme may improve + exportability and avoid other legal constraints on usage. Alice + sends the signature value to Bob along with both the message and + its hash result. The algorithm enables Bob to use Alice's public + + + +Shirey Informational [Page 105] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + signature key and the signature value to verify the hash result he + receives. Then, as before, he compares that hash result she sent + to the one that he computes by hashing the message himself. + + $ Digital Signature Algorithm (DSA) + (N) An asymmetric cryptographic algorithm for a digital signature + in the form of a pair of large numbers. The signature is computed + using rules and parameters such that the identity of the signer + and the integrity of the signed data can be verified. (See: DSS.) + + $ Digital Signature Standard (DSS) + (N) The U.S. Government standard [FP186] that specifies the DSA. + + $ digital watermarking + (I) Computing techniques for inseparably embedding unobtrusive + marks or labels as bits in digital data -- text, graphics, images, + video, or audio -- and for detecting or extracting the marks + later. + + Tutorial: A "digital watermark", i.e., the set of embedded bits, + is sometimes hidden, usually imperceptible, and always intended to + be unobtrusive. Depending on the particular technique that is + used, digital watermarking can assist in proving ownership, + controlling duplication, tracing distribution, ensuring data + integrity, and performing other functions to protect intellectual + property rights. [ACM] + + $ digitized signature + (D) Denotes various forms of digitized images of handwritten + signatures. (Compare: digital signature). + + Deprecated Term: IDOCs SHOULD NOT use this term without including + this definition. This term suggests careless use of "digital + signature", which is the term standardized by [I7498-2]. (See: + electronic signature.) + + $ DII + (O) See: Defense Information Infrastructure. + + $ direct attack + (I) See: secondary definition under "attack". (Compare: indirect + attack.) + + $ directory, Directory + 1. (I) /not capitalized/ Refers generically to a database server + or other system that stores and provides access to values of + descriptive or operational data items that are associated with the + components of a system. (Compare: repository.) + + + +Shirey Informational [Page 106] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + 2. (N) /capitalized/ Refers specifically to the X.500 Directory. + (See: DN, X.500.) + + $ Directory Access Protocol (DAP) + (N) An OSI protocol [X519] for communication between a Directory + User Agent (a type of X.500 client) and a Directory System Agent + (a type of X.500 server). (See: LDAP.) + + $ disaster plan + (O) Synonym for "contingency plan". + + Deprecated Term: IDOCs SHOULD NOT use this term; instead, for + consistency and neutrality of language, IDOCs SHOULD use + "contingency plan". + + $ disclosure + See: unauthorized disclosure. Compare: exposure. + + $ discretionary access control + 1a. (I) An access control service that (a) enforces a security + policy based on the identity of system entities and the + authorizations associated with the identities and (b) incorporates + a concept of ownership in which access rights for a system + resource may be granted and revoked by the entity that owns the + resource. (See: access control list, DAC, identity-based security + policy, mandatory access control.) + + Derivation: This service is termed "discretionary" because an + entity can be granted access rights to a resource such that the + entity can by its own volition enable other entities to access the + resource. + + 1b. (O) /formal model/ "A means of restricting access to objects + based on the identity of subjects and/or groups to which they + belong. The controls are discretionary in the sense that a subject + with a certain access permission is capable of passing that + permission (perhaps indirectly) on to any other subject." [DoD1] + + $ DISN + (O) See: Defense Information Systems Network (DISN). + + $ disruption + (I) A circumstance or event that interrupts or prevents the + correct operation of system services and functions. (See: + availability, critical, system integrity, threat consequence.) + + + + + + +Shirey Informational [Page 107] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Tutorial: Disruption is a type of threat consequence; it can be + caused by the following types of threat actions: incapacitation, + corruption, and obstruction. + + $ Distinguished Encoding Rules (DER) + (N) A subset of the Basic Encoding Rules that always provides only + one way to encode any data structure defined by ASN.1. [X690]. + + Tutorial: For a data structure defined abstractly in ASN.1, BER + often provides for encoding the structure into an octet string in + more than one way, so that two separate BER implementations can + legitimately produce different octet strings for the same ASN.1 + definition. However, some applications require all encodings of a + structure to be the same, so that encodings can be compared for + equality. Therefore, DER is used in applications in which unique + encoding is needed, such as when a digital signature is computed + on a structure defined by ASN.1. + + $ distinguished name (DN) + (N) An identifier that uniquely represents an object in the X.500 + Directory Information Tree (DIT) [X501]. (Compare: domain name, + identity, naming authority.) + + Tutorial: A DN is a set of attribute values that identify the path + leading from the base of the DIT to the object that is named. An + X.509 public-key certificate or CRL contains a DN that identifies + its issuer, and an X.509 attribute certificate contains a DN or + other form of name that identifies its subject. + + $ distributed attack + 1a. (I) An attack that is implemented with distributed computing. + (See: zombie.) + + 1b. (I) An attack that deploys multiple threat agents. + + $ Distributed Authentication Security Service (DASS) + (I) An experimental Internet protocol [R1507] that uses + cryptographic mechanisms to provide strong, mutual authentication + services in a distributed environment. + + $ distributed computing + (I) A technique that disperses a single, logically related set of + tasks among a group of geographically separate yet cooperating + computers. (See: distributed attack.) + + + + + + + +Shirey Informational [Page 108] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ distribution point + (I) An X.500 Directory entry or other information source that is + named in a v3 X.509 public-key certificate extension as a location + from which to obtain a CRL that may list the certificate. + + Tutorial: A v3 X.509 public-key certificate may have a + "cRLDistributionPoints" extension that names places to get CRLs on + which the certificate might be listed. (See: certificate profile.) + A CRL obtained from a distribution point may (a) cover either all + reasons for which a certificate might be revoked or only some of + the reasons, (b) be issued by either the authority that signed the + certificate or some other authority, and (c) contain revocation + entries for only a subset of the full set of certificates issued + by one CA or (d) contain revocation entries for multiple CAs. + + $ DKIM + (I) See: Domain Keys Identified Mail. + + $ DMZ + (D) See: demilitarized zone. + + $ DN + (N) See: distinguished name. + + $ DNS + (I) See: Domain Name System. + + $ doctrine + See: security doctrine. + + $ DoD + (N) Department of Defense. + + Usage: To avoid international misunderstanding, IDOCs SHOULD use + this abbreviation only with a national qualifier (e.g., U.S. DoD). + + $ DOI + (I) See: Domain of Interpretation. + + $ domain + 1a. (I) /general security/ An environment or context that (a) + includes a set of system resources and a set of system entities + that have the right to access the resources and (b) usually is + defined by a security policy, security model, or security + architecture. (See: CA domain, domain of interpretation, security + perimeter. Compare: COI, enclave.) + + + + + +Shirey Informational [Page 109] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Tutorial: A "controlled interface" or "guard" is required to + transfer information between network domains that operate under + different security policies. + + 1b. (O) /security policy/ A set of users, their information + objects, and a common security policy. [DoD6, SP33] + + 1c. (O) /security policy/ A system or collection of systems that + (a) belongs to a community of interest that implements a + consistent security policy and (b) is administered by a single + authority. + + 2. (O) /COMPUSEC/ An operating state or mode of a set of computer + hardware. + + Tutorial: Most computers have at least two hardware operating + modes [Gass]: + - "Privileged" mode: a.k.a. "executive", "master", "system", + "kernel", or "supervisor" mode. In this mode, software can + execute all machine instructions and access all storage + locations. + - "Unprivileged" mode: a.k.a. "user", "application", or "problem" + mode. In this mode, software is restricted to a subset of the + instructions and a subset of the storage locations. + + 3. (O) "A distinct scope within which certain common + characteristics are exhibited and common rules are observed." + [CORBA] + + 4. (O) /MISSI/ The domain of a MISSI CA is the set of MISSI users + whose certificates are signed by the CA. + + 5. (I) /Internet/ That part of the tree-structured name space of + the DNS that is at or below the name that specifies the domain. A + domain is a subdomain of another domain if it is contained within + that domain. For example, D.C.B.A is a subdomain of C.B.A + + 6. (O) /OSI/ An administrative partition of a complex distributed + OSI system. + + $ Domain Keys Identified Mail (DKIM) + (I) A protocol, which is being specified by the IETF working group + of the same name, to provide data integrity and domain-level (see: + DNS, domain name) data origin authentication for Internet mail + messages. (Compare: PEM.) + + Tutorial: DKIM employs asymmetric cryptography to create a digital + signature for an Internet email message's body and selected + + + +Shirey Informational [Page 110] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + headers (see RFC 1822), and the signature is then carried in a + header of the message. A recipient of the message can verify the + signature and, thereby, authenticate the identity of the + originating domain and the integrity of the signed content, by + using a public key belonging to the domain. The key can be + obtained from the DNS. + + $ domain name + (I) The style of identifier that is defined for subtrees in the + Internet DNS -- i.e., a sequence of case-insensitive ASCII labels + separated by dots (e.g., "bbn.com") -- and also is used in other + types of Internet identifiers, such as host names (e.g., + "rosslyn.bbn.com"), mailbox names (e.g., "rshirey@bbn.com") and + URLs (e.g., "http://www.rosslyn.bbn.com/foo"). (See: domain. + Compare: DN.) + + Tutorial: The name space of the DNS is a tree structure in which + each node and leaf holds records describing a resource. Each node + has a label. The domain name of a node is the list of labels on + the path from the node to the root of the tree. The labels in a + domain name are printed or read left to right, from the most + specific (lowest, farthest from the root) to the least specific + (highest, closest to the root), but the root's label is the null + string. (See: country code.) + + $ Domain Name System (DNS) + (I) The main Internet operations database, which is distributed + over a collection of servers and used by client software for + purposes such as (a) translating a domain name-style host name + into an IP address (e.g., "rosslyn.bbn.com" translates to + "192.1.7.10") and (b) locating a host that accepts mail for a + given mailbox address. (RFC 1034) (See: domain name.) + + Tutorial: The DNS has three major components: + - Domain name space and resource records: Specifications for the + tree-structured domain name space, and data associated with the + names. + - Name servers: Programs that hold information about a subset of + the tree's structure and data holdings, and also hold pointers + to other name servers that can provide information from any + part of the tree. + - Resolvers: Programs that extract information from name servers + in response to client requests; typically, system routines + directly accessible to user programs. + + Extensions to the DNS [R4033, R4034, R4035] support (a) key + distribution for public keys needed for the DNS and for other + protocols, (b) data origin authentication service and data + + + +Shirey Informational [Page 111] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + integrity service for resource records, (c) data origin + authentication service for transactions between resolvers and + servers, and (d) access control of records. + + $ domain of interpretation (DOI) + (I) /IPsec/ A DOI for ISAKMP or IKE defines payload formats, + exchange types, and conventions for naming security-relevant + information such as security policies or cryptographic algorithms + and modes. Example: See [R2407]. + + Derivation: The DOI concept is based on work by the TSIG's CIPSO + Working Group. + + $ dominate + (I) Security level A is said to "dominate" security level B if the + (hierarchical) classification level of A is greater (higher) than + or equal to that of B, and A's (nonhierarchical) categories + include (as a subset) all of B's categories. (See: lattice, + lattice model.) + + $ dongle + (I) A portable, physical, usually electronic device that is + required to be attached to a computer to enable a particular + software program to run. (See: token.) + + Tutorial: A dongle is essentially a physical key used for copy + protection of software; that is, the program will not run unless + the matching dongle is attached. When the software runs, it + periodically queries the dongle and quits if the dongle does not + reply with the proper authentication information. Dongles were + originally constructed as an EPROM (erasable programmable read- + only memory) to be connected to a serial input-output port of a + personal computer. + + $ downgrade + (I) /data security/ Reduce the security level of data (especially + the classification level) without changing the information content + of the data. (Compare: downgrade.) + + $ downgrade attack + (I) A type of man-in-the-middle attack in which the attacker can + cause two parties, at the time they negotiate a security + association, to agree on a lower level of protection than the + highest level that could have been supported by both of them. + (Compare: downgrade.) + + + + + + +Shirey Informational [Page 112] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ draft RFC + (D) A preliminary, temporary version of a document that is + intended to become an RFC. (Compare: Internet-Draft.) + + Deprecated Term: IDOCs SHOULD NOT use this term. The RFC series is + archival in nature and consists only of documents in permanent + form. A document that is intended to become an RFC usually needs + to be published first as an Internet-Draft (RFC 2026). (See: + "Draft Standard" under "Internet Standard".) + + $ Draft Standard + (I) See: secondary definition under "Internet Standard". + + $ DSA + (N) See: Digital Signature Algorithm. + + $ DSS + (N) See: Digital Signature Standard. + + $ dual control + (I) A procedure that uses two or more entities (usually persons) + operating in concert to protect a system resource, such that no + single entity acting alone can access that resource. (See: no-lone + zone, separation of duties, split knowledge.) + + $ dual signature + (O) /SET/ A single digital signature that protects two separate + messages by including the hash results for both sets in a single + encrypted value. [SET2] + + Deprecated Usage: IDOCs SHOULD NOT use this term except when + qualified as "SET(trademark) dual signature" with this definition. + + Tutorial: Generated by hashing each message separately, + concatenating the two hash results, and then hashing that value + and encrypting the result with the signer's private key. Done to + reduce the number of encryption operations and to enable + verification of data integrity without complete disclosure of the + data. + + $ dual-use certificate + (O) A certificate that is intended for use with both digital + signature and data encryption services. [SP32] + + Usage: IDOCs that use this term SHOULD state a definition for it + by identifying the intended uses of the certificate, because there + are more than just these two uses mentioned in the NIST + publication. A v3 X.509 public-key certificate may have a "key + + + +Shirey Informational [Page 113] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Usage" extension, which indicates the purposes for which the + public key may be used. (See: certificate profile.) + + $ duty + (I) An attribute of a role that obligates an entity playing the + role to perform one or more tasks, which usually are essential for + the functioning of the system. [Sand] (Compare authorization, + privilege. See: role, billet.) + + $ e-cash + (O) Electronic cash; money that is in the form of data and can be + used as a payment mechanism on the Internet. (See: IOTP.) + + Usage: IDOCs that use this term SHOULD state a definition for it + because many different types of electronic cash have been devised + with a variety of security mechanisms. + + $ EAP + (I) See: Extensible Authentication Protocol. + + $ EAL + (O) See: evaluation assurance level. + + $ Easter egg + (O) "Hidden functionality within an application program, which + becomes activated when an undocumented, and often convoluted, set + of commands and keystrokes is entered. Easter eggs are typically + used to display the credits for the development team and [are] + intended to be non-threatening" [SP28], but Easter eggs have the + potential to contain malicious code. + + Deprecated Usage: It is likely that other cultures use different + metaphors for this concept. Therefore, to avoid international + misunderstanding, IDOCs SHOULD NOT use this term. (See: Deprecated + Usage under "Green Book".) + + $ eavesdropping + (I) Passive wiretapping done secretly, i.e., without the knowledge + of the originator or the intended recipients of the communication. + + $ ECB + (N) See: electronic codebook. + + $ ECDSA + (N) See: Elliptic Curve Digital Signature Algorithm. + + + + + + +Shirey Informational [Page 114] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ economy of alternatives + (I) The principle that a security mechanism should be designed to + minimize the number of alternative ways of achieving a service. + (Compare: economy of mechanism.) + + $ economy of mechanism + (I) The principle that a security mechanism should be designed to + be as simple as possible, so that (a) the mechanism can be + correctly implemented and (b) it can be verified that the + operation of the mechanism enforces the system's security policy. + (Compare: economy of alternatives, least privilege.) + + $ ECU + (N) See: end cryptographic unit. + + $ EDI + (I) See: electronic data interchange. + + $ EDIFACT + (N) See: secondary definition under "electronic data interchange". + + $ EE + (D) Abbreviation of "end entity" and other terms. + + Deprecated Abbreviation: IDOCs SHOULD NOT use this abbreviation; + there could be confusion among "end entity", "end-to-end + encryption", "escrowed encryption standard", and other terms. + + $ EES + (O) See: Escrowed Encryption Standard. + + $ effective key length + (O) "A measure of strength of a cryptographic algorithm, + regardless of actual key length." [IATF] (See: work factor.) + + $ effectiveness + (O) /ITSEC/ A property of a TOE representing how well it provides + security in the context of its actual or proposed operational use. + + $ El Gamal algorithm + (N) An algorithm for asymmetric cryptography, invented in 1985 by + Taher El Gamal, that is based on the difficulty of calculating + discrete logarithms and can be used for both encryption and + digital signatures. [ElGa] + + + + + + + +Shirey Informational [Page 115] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ electronic codebook (ECB) + (N) A block cipher mode in which a plaintext block is used + directly as input to the encryption algorithm and the resultant + output block is used directly as cipher text [FP081]. (See: block + cipher, [SP38A].) + + $ electronic commerce + 1. (I) Business conducted through paperless exchanges of + information, using electronic data interchange, electronic funds + transfer (EFT), electronic mail, computer bulletin boards, + facsimile, and other paperless technologies. + + 2. (O) /SET/ "The exchange of goods and services for payment + between the cardholder and merchant when some or all of the + transaction is performed via electronic communication." [SET2] + + $ electronic data interchange (EDI) + (I) Computer-to-computer exchange, between trading partners, of + business data in standardized document formats. + + Tutorial: EDI formats have been standardized primarily by ANSI X12 + and by EDIFACT (EDI for Administration, Commerce, and + Transportation), which is an international, UN-sponsored standard + primarily used in Europe and Asia. X12 and EDIFACT are aligning to + create a single, global EDI standard. + + $ Electronic Key Management System (EKMS) + (O) "Interoperable collection of systems developed by ... the U.S. + Government to automate the planning, ordering, generating, + distributing, storing, filling, using, and destroying of + electronic keying material and the management of other types of + COMSEC material." [C4009] + + $ electronic signature + (D) Synonym for "digital signature" or "digitized signature". + + Deprecated Term: IDOCs SHOULD NOT use this term; there is no + current consensus on its definition. Instead, use "digital + signature", if that is what was intended + + $ electronic wallet + (D) A secure container to hold, in digitized form, some sensitive + data objects that belong to the owner, such as electronic money, + authentication material, and various types of personal + information. (See: IOTP.) + + Deprecated Term: IDOCs SHOULD NOT use this term. There is no + current consensus on its definition; and some uses and definitions + + + +Shirey Informational [Page 116] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + may be proprietary. Meanings range from virtual wallets + implemented by data structures to physical wallets implemented by + cryptographic tokens. (See: Deprecated Usage under "Green Book".) + + $ elliptic curve cryptography (ECC) + (I) A type of asymmetric cryptography based on mathematics of + groups that are defined by the points on a curve, where the curve + is defined by a quadratic equation in a finite field. [Schn] + + Tutorial: ECC is based on mathematics different than that + originally used to define the Diffie-Hellman-Merkle algorithm and + the DSA, but ECC can be used to define an algorithm for key + agreement that is an analog of Diffie-Hellman-Merkle [A9063] and + an algorithm for digital signature that is an analog of DSA + [A9062]. The mathematical problem upon which ECC is based is + believed to be more difficult than the problem upon which Diffie- + Hellman-Merkle is based and, therefore, that keys for ECC can be + shorter for a comparable level of security. (See: ECDSA.) + + $ Elliptic Curve Digital Signature Algorithm (ECDSA) + (N) A standard [A9062] that is the analog, in elliptic curve + cryptography, of the Digital Signature Algorithm. + + $ emanation + (I) A signal (e.g., electromagnetic or acoustic) that is emitted + by a system (e.g., through radiation or conductance) as a + consequence (i.e., byproduct) of the system's operation, and that + may contain information. (See: emanations security.) + + $ emanations analysis + (I) /threat action/ See: secondary definition under + "interception". + + $ emanations security (EMSEC) + (I) Physical security measures to protect against data compromise + that could occur because of emanations that might be received and + read by an unauthorized party. (See: emanation, TEMPEST.) + + Usage: Refers either to preventing or limiting emanations from a + system and to preventing or limiting the ability of unauthorized + parties to receive the emissions. + + $ embedded cryptography + (N) "Cryptography engineered into an equipment or system whose + basic function is not cryptographic." [C4009] + + $ emergency plan + (D) Synonym for "contingency plan". + + + +Shirey Informational [Page 117] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Deprecated Term: IDOCs SHOULD NOT use this term. Instead, for + neutrality and consistency of language, use "contingency plan". + + $ emergency response + (O) An urgent response to a fire, flood, civil commotion, natural + disaster, bomb threat, or other serious situation, with the intent + of protecting lives, limiting damage to property, and minimizing + disruption of system operations. [FP087] (See: availability, CERT, + emergency plan.) + + $ EMSEC + (I) See: emanations security. + + $ EMV + (N) Abbreviation of "Europay, MasterCard, Visa". Refers to a + specification for smart cards that are used as payment cards, and + for related terminals and applications. [EMV1, EMV2, EMV3] + + $ Encapsulating Security Payload (ESP) + (I) An Internet protocol [R2406, R4303] designed to provide data + confidentiality service and other security services for IP + datagrams. (See: IPsec. Compare: AH.) + + Tutorial: ESP may be used alone, or in combination with AH, or in + a nested fashion with tunneling. Security services can be provided + between a pair of communicating hosts, between a pair of + communicating security gateways, or between a host and a gateway. + The ESP header is encapsulated by the IP header, and the ESP + header encapsulates either the upper-layer protocol header + (transport mode) or an IP header (tunnel mode). ESP can provide + data confidentiality service, data origin authentication service, + connectionless data integrity service, an anti-replay service, and + limited traffic-flow confidentiality. The set of services depends + on the placement of the implementation and on options selected + when the security association is established. + + $ encipher + (D) Synonym for "encrypt". + + Deprecated Definition: IDOCs SHOULD NOT use this term as a synonym + for "encrypt". However, see Usage note under "encryption". + + $ encipherment + (D) Synonym for "encryption". + + Deprecated Definition: IDOCs SHOULD NOT use this term as a synonym + for "encryption". However, see Usage note under "encryption". + + + + +Shirey Informational [Page 118] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ enclave + 1. (I) A set of system resources that operate in the same security + domain and that share the protection of a single, common, + continuous security perimeter. (Compare: domain.) + + 2. (D) /U.S. Government/ "Collection of computing environments + connected by one or more internal networks under the control of a + single authority and security policy, including personnel and + physical security." [C4009] + + Deprecated Definition: IDOCs SHOULD NOT use this term with + definition 2 because the definition applies to what is usually + called a "security domain". That is, a security domain is a set of + one or more security enclaves. + + $ encode + 1. (I) Use a system of symbols to represent information, which + might originally have some other representation. Example: Morse + code. (See: ASCII, BER.) (See: code, decode.) + + 2. (D) Synonym for "encrypt". + + Deprecated Definition: IDOCs SHOULD NOT use this term as a synonym + for "encrypt"; encoding is not always meant to conceal meaning. + + $ encrypt + (I) Cryptographically transform data to produce cipher text. (See: + encryption. Compare: seal.) + + $ encryption + 1. (I) Cryptographic transformation of data (called "plain text") + into a different form (called "cipher text") that conceals the + data's original meaning and prevents the original form from being + used. The corresponding reverse process is "decryption", a + transformation that restores encrypted data to its original form. + (See: cryptography.) + + 2. (O) "The cryptographic transformation of data to produce + ciphertext." [I7498-2] + + Usage: For this concept, IDOCs SHOULD use the verb "to encrypt" + (and related variations: encryption, decrypt, and decryption). + However, because of cultural biases involving human burial, some + international documents (particularly ISO and CCITT standards) + avoid "to encrypt" and instead use the verb "to encipher" (and + related variations: encipherment, decipher, decipherment). + + + + + +Shirey Informational [Page 119] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Tutorial: Usually, the plaintext input to an encryption operation + is clear text. But in some cases, the plain text may be cipher + text that was output from another encryption operation. (See: + superencryption.) + + Encryption and decryption involve a mathematical algorithm for + transforming data. Besides the data to be transformed, the + algorithm has one or more inputs that are control parameters: (a) + a key that varies the transformation and, in some cases, (b) an IV + that establishes the starting state of the algorithm. + + $ encryption certificate + (I) A public-key certificate that contains a public key that is + intended to be used for encrypting data, rather than for verifying + digital signatures or performing other cryptographic functions. + + Tutorial: A v3 X.509 public-key certificate may have a "keyUsage" + extension that indicates the purpose for which the certified + public key is intended. (See: certificate profile.) + + $ end cryptographic unit (ECU) + 1. (N) Final destination device into which a key is loaded for + operational use. + + 2. (N) A device that (a) performs cryptographic functions, (b) + typically is part of a larger system for which the device provides + security services, and (c), from the viewpoint of a supporting + security infrastructure such as a key management system, is the + lowest level of identifiable component with which a management + transaction can be conducted + + $ end entity + 1. (I) A system entity that is the subject of a public-key + certificate and that is using, or is permitted and able to use, + the matching private key only for purposes other than signing a + digital certificate; i.e., an entity that is not a CA. + + 2. (O) "A certificate subject [that] uses its public [sic] key for + purposes other than signing certificates." [X509] + + Deprecated Definition: IDOCs SHOULD NOT use definition 2, which is + misleading and incomplete. First, that definition should have said + "private key" rather than "public key" because certificates are + not usefully signed with a public key. Second, the X.509 + definition is ambiguous regarding whether an end entity may or may + not use the private key to sign a certificate, i.e., whether the + subject may be a CA. The intent of X.509's authors was that an end + entity certificate is not valid for use in verifying a signature + + + +Shirey Informational [Page 120] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + on an X.509 certificate or X.509 CRL. Thus, it would have been + better for the X.509 definition to have said "only for purposes + other than signing certificates". + + Usage: Despite the problems in the X.509 definition, the term + itself is useful in describing applications of asymmetric + cryptography. The way the term is used in X.509 implies that it + was meant to be defined, as we have done here, relative to roles + that an entity (which is associated with an OSI end system) is + playing or is permitted to play in applications of asymmetric + cryptography other than the PKI that supports applications. + + Tutorial: Whether a subject can play both CA and non-CA roles, + with either the same or different certificates, is a matter of + policy. (See: CPS.) A v3 X.509 public-key certificate may have a + "basicConstraints" extension containing a "cA" value that + specifically "indicates whether or not the public key may be used + to verify certificate signatures". (See: certificate profile.) + + $ end system + (N) /OSIRM/ A computer that implements all seven layers of the + OSIRM and may attach to a subnetwork. Usage: In the IPS context, + an end system is called a "host". + + $ end-to-end encryption + (I) Continuous protection of data that flows between two points in + a network, effected by encrypting data when it leaves its source, + keeping it encrypted while it passes through any intermediate + computers (such as routers), and decrypting it only when it + arrives at the intended final destination. (See: wiretapping. + Compare: link encryption.) + + Examples: A few are BLACKER, CANEWARE, IPLI, IPsec, PLI, SDNS, + SILS, SSH, SSL, TLS. + + Tutorial: When two points are separated by multiple communication + links that are connected by one or more intermediate relays, end- + to-end encryption enables the source and destination systems to + protect their communications without depending on the intermediate + systems to provide the protection. + + $ end user + 1. (I) /information system/ A system entity, usually a human + individual, that makes use of system resources, primarily for + application purposes as opposed to system management purposes. + + 2. (D) /PKI/ Synonym for "end entity". + + + + +Shirey Informational [Page 121] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Deprecated Definition: IDOCs SHOULD NOT use "end user" as a + synonym for "end entity", because that would mix concepts in a + potentially misleading way. + + $ endorsed-for-unclassified cryptographic item (EUCI) + (O) /U.S. Government/ "Unclassified cryptographic equipment that + embodies a U.S. Government classified cryptographic logic and is + endorsed by NSA for the protection of national security + information." [C4009] (Compare: CCI, type 2 product.) + + $ entity + See: system entity. + + $ entrapment + (I) "The deliberate planting of apparent flaws in a system for the + purpose of detecting attempted penetrations or confusing an + intruder about which flaws to exploit." [FP039] (See: honey pot.) + + $ entropy + 1. (I) An information-theoretic measure (usually stated as a + number of bits) of the amount of uncertainty that an attacker + faces to determine the value of a secret. [SP63] (See: strength.) + + Example: If a password is said to contain at least 20 bits of + entropy, that means that it must be as hard to find the password + as to guess a 20-bit random number. + + 2. (I) An information-theoretic measure (usually stated as a + number of bits) of the amount of information in a message; i.e., + the minimum number of bits needed to encode all possible meanings + of that message. [Schn] (See: uncertainty.) + + $ ephemeral + (I) /adjective/ Refers to a cryptographic key or other + cryptographic parameter or data object that is short-lived, + temporary, or used one time. (See: session key. Compare: static.) + + $ erase + 1. (I) Delete stored data. (See: sanitize, zeroize.) + + 2. (O) /U.S. Government/ Delete magnetically stored data in such a + way that the data cannot be recovered by ordinary means, but might + be recoverable by laboratory methods. [C4009] (Compare: /U.S. + Government/ purge.) + + $ error detection code + (I) A checksum designed to detect, but not correct, accidental + (i.e., unintentional) changes in data. + + + +Shirey Informational [Page 122] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ Escrowed Encryption Standard (EES) + (N) A U.S. Government standard [FP185] that specifies how to use a + symmetric encryption algorithm (SKIPJACK) and create a Law + Enforcement Access Field (LEAF) for implementing part of a key + escrow system that enables decryption of telecommunications when + interception is lawfully authorized. + + Tutorial: Both SKIPJACK and the LEAF are intended for use in + equipment used to encrypt and decrypt sensitive, unclassified, + telecommunications data. + + $ ESP + (I) See: Encapsulating Security Payload. + + $ Estelle + (N) A language (ISO 9074-1989) for formal specification of + computer network protocols. + + $ ETSI + (N) See: European Telecommunication Standards Institute. + + $ EUCI + (O) See: endorsed-for-unclassified cryptographic item. + + $ European Telecommunication Standards Institute (ETSI) + (N) An independent, non-profit organization, based in France, that + is officially recognized by the European Commission and + responsible for standardization of information and communication + technologies within Europe. + + Tutorial: ETSI maintains the standards for a number of security + algorithms, including encryption algorithms for mobile telephone + systems in Europe. + + $ evaluated system + (I) A system that has been evaluated against security criteria + (for example, against the TCSEC or against a profile based on the + Common Criteria). + + $ evaluation + (I) Assessment of an information system against defined security + criteria (for example, against the TCSEC or against a profile + based on the Common Criteria). (Compare: certification.) + + $ evaluation assurance level (EAL) + (N) A predefined package of assurance components that represents a + point on the Common Criteria's scale for rating confidence in the + security of information technology products and systems. + + + +Shirey Informational [Page 123] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Tutorial: The Common Criteria defines a scale of seven, + hierarchically ordered EALs for rating a TOE. From highest to + lowest, they are as follows: + - EAL7. Formally verified design and tested. + - EAL6. Semiformally verified design and tested. + - EAL5. Semiformally designed and tested. + - EAL4. Methodically designed, tested, and reviewed. + - EAL3. Methodically tested and checked. + - EAL2. Structurally tested. + - EAL1. Functionally tested. + + An EAL is a consistent, baseline set of requirements. The increase + in assurance from EAL to EAL is accomplished by substituting + higher assurance components (i.e., criteria of increasing rigor, + scope, or depth) from seven assurance classes: (a) configuration + management, (b) delivery and operation, (c) development, (d) + guidance documents, (e) lifecycle support, (f) tests, and (g) + vulnerability assessment. + + The EALs were developed with the goal of preserving concepts of + assurance that were adopted from earlier criteria, so that results + of previous evaluations would remain relevant. For example, EALs + levels 2-7 are generally equivalent to the assurance portions of + the TCSEC C2-A1 scale. However, this equivalency should be used + with caution. The levels do not derive assurance in the same + manner, and exact mappings do not exist. + + $ expire + (I) /credential/ Cease to be valid (i.e., change from being valid + to being invalid) because its assigned lifetime has been exceeded. + (See: certificate expiration.) + + $ exposure + (I) A type of threat action whereby sensitive data is directly + released to an unauthorized entity. (See: unauthorized + disclosure.) + + Usage: This type of threat action includes the following subtypes: + - "Deliberate Exposure": Intentional release of sensitive data to + an unauthorized entity. + - "Scavenging": Searching through data residue in a system to + gain unauthorized knowledge of sensitive data. + - "Human error": /exposure/ Human action or inaction that + unintentionally results in an entity gaining unauthorized + knowledge of sensitive data. (Compare: corruption, + incapacitation.) + - "Hardware or software error": /exposure/ System failure that + unintentionally results in an entity gaining unauthorized + + + +Shirey Informational [Page 124] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + knowledge of sensitive data. (Compare: corruption, + incapacitation.) + + $ Extended Security Option + (I) See: secondary definition under "IPSO". + + $ Extensible Authentication Protocol (EAP) + (I) An extension framework for PPP that supports multiple, + optional authentication mechanisms, including cleartext passwords, + challenge-response, and arbitrary dialog sequences. [R3748] + (Compare: GSS-API, SASL.) + + Tutorial: EAP typically runs directly over IPS data link protocols + or OSIRM Layer 2 protocols, i.e., without requiring IP. + Originally, EAP was developed for use in PPP, by a host or router + that connects to a network server via switched circuits or dial-up + lines. Today, EAP's domain of applicability includes other areas + of network access control; it is used in wired and wireless LANs + with IEEE 802.1X, and in IPsec with IKEv2. EAP is conceptually + related to other authentication mechanism frameworks, such as SASL + and GSS-API. + + $ Extensible Markup Language (XML) + (N) A version of Standard Generalized Markup Language (ISO 8879) + that separately represents a document's content and its structure. + XML was designed by W3C for use on the World Wide Web. + + $ extension + (I) /protocol/ A data item or a mechanism that is defined in a + protocol to extend the protocol's basic or original functionality. + + Tutorial: Many protocols have extension mechanisms, and the use of + these extension is usually optional. IP and X.509 are two examples + of protocols that have optional extensions. In IP version 4, + extensions are called "options", and some of the options have + security purposes (see: IPSO). + + In X.509, certificate and CRL formats can be extended to provide + methods for associating additional attributes with subjects and + public keys and for managing a certification hierarchy: + - A "certificate extension": X.509 defines standard extensions + that may be included in v3 certificates to provide additional + key and security policy information, subject and issuer + attributes, and certification path constraints. + - A "CRL extension": X.509 defines extensions that may be + included in v2 CRLs to provide additional issuer key and name + information, revocation reasons and constraints, and + information about distribution points and delta CRLs. + + + +Shirey Informational [Page 125] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + - A "private extension": Additional extensions, each named by an + OID, can be locally defined as needed by applications or + communities. (See: Authority Information Access extension, SET + private extensions.) + + $ external controls + (I) /COMPUSEC/ Refers to administrative security, personnel + security, and physical security. (Compare: internal controls.) + + $ extranet + (I) A computer network that an organization uses for application + data traffic between the organization and its business partners. + (Compare: intranet.) + + Tutorial: An extranet can be implemented securely, either on the + Internet or using Internet technology, by constructing the + extranet as a VPN. + + $ extraction resistance + (O) Ability of cryptographic equipment to resist efforts to + extract keying material directly from the equipment (as opposed to + gaining knowledge of keying material by cryptanalysis). [C4009] + + $ extrusion detection + (I) Monitoring for unauthorized transfers of sensitive information + and other communications that originate inside a system's security + perimeter and are directed toward the outside; i.e., roughly the + opposite of "intrusion detection". + + $ fail-safe + 1. (I) Synonym for "fail-secure". + + 2. (I) A mode of termination of system functions that prevents + damage to specified system resources and system entities (i.e., + specified data, property, and life) when a failure occurs or is + detected in the system (but the failure still might cause a + security compromise). (See: failure control.) + + Tutorial: Definitions 1 and 2 are opposing design alternatives. + Therefore, IDOCs SHOULD NOT use this term without providing a + definition for it. If definition 1 is intended, IDOCs can avoid + ambiguity by using "fail-secure" instead. + + $ fail-secure + (I) A mode of termination of system functions that prevents loss + of secure state when a failure occurs or is detected in the system + (but the failure still might cause damage to some system resource + or system entity). (See: failure control. Compare: fail-safe.) + + + +Shirey Informational [Page 126] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ fail-soft + (I) Selective termination of affected, non-essential system + functions when a failure occurs or is detected in the system. + (See: failure control.) + + $ failure control + (I) A methodology used to provide fail-safe, fail-secure or fail- + soft termination and recovery of system functions. [FP039] + + $ fairness + (I) A property of an access protocol for a system resource whereby + the resource is made equitably or impartially available to all + eligible users. (RFC 3753) + + Tutorial: Fairness can be used to defend against some types of + denial-of-service attacks on a system connected to a network. + However, this technique assumes that the system can properly + receive and process inputs from the network. Therefore, the + technique can mitigate flooding but is ineffective against + jamming. + + $ falsification + (I) A type of threat action whereby false data deceives an + authorized entity. (See: active wiretapping, deception.) + + Usage: This type of threat action includes the following subtypes: + - "Substitution": Altering or replacing valid data with false + data that serves to deceive an authorized entity. + - "Insertion": Introducing false data that serves to deceive an + authorized entity. + + $ fault tree + (I) A branching, hierarchical data structure that is used to + represent events and to determine the various combinations of + component failures and human acts that could result in a specified + undesirable system event. (See: attack tree, flaw hypothesis + methodology.) + + Tutorial: "Fault-tree analysis" is a technique in which an + undesired state of a system is specified and the system is studied + in the context of its environment and operation to find all + credible ways in which the event could occur. The specified fault + event is represented as the root of the tree. The remainder of the + tree represents AND or OR combinations of subevents, and + sequential combinations of subevents, that could cause the root + event to occur. The main purpose of a fault-tree analysis is to + calculate the probability of the root event, using statistics or + other analytical methods and incorporating actual or predicted + + + +Shirey Informational [Page 127] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + quantitative reliability and maintainability data. When the root + event is a security violation, and some of the subevents are + deliberate acts intended to achieve the root event, then the fault + tree is an attack tree. + + $ FEAL + (O) A family of symmetric block ciphers that was developed in + Japan; uses a 64-bit block, keys of either 64 or 128 bits, and a + variable number of rounds; and has been successfully attacked by + cryptanalysts. [Schn] + + $ Federal Information Processing Standards (FIPS) + (N) The Federal Information Processing Standards Publication (FIPS + PUB) series issued by NIST under the provisions of Section 111(d) + of the Federal Property and Administrative Services Act of 1949 as + amended by the Computer Security Act of 1987 (Public Law 100-235) + as technical guidelines for U.S. Government procurements of + information processing system equipment and services. (See: + "[FPxxx]" items in Section 7, Informative References.) + + $ Federal Public-key Infrastructure (FPKI) + (O) A PKI being planned to establish facilities, specifications, + and policies needed by the U.S. Government to use public-key + certificates in systems involving unclassified but sensitive + applications and interactions between Federal agencies as well as + with entities of state and local governments, the business + community, and the public. [FPKI] + + $ Federal Standard 1027 + (N) An U.S. Government document defining emanation, anti-tamper, + security fault analysis, and manual key management criteria for + DES encryption devices, primary for OSIRM Layer 2. Was renamed + "FIPS PUB 140" when responsibility for protecting unclassified, + sensitive information was transferred from NSA to NIST, and has + since been superseded by newer versions of that standard [FP140]. + + $ File Transfer Protocol (FTP) + (I) A TCP-based, Application-Layer, Internet Standard protocol + (RFC 959) for moving data files from one computer to another. + + $ fill device + (N) /COMSEC/ A device used to transfer or store keying material in + electronic form or to insert keying material into cryptographic + equipment. + + $ filter + 1. (I) /noun/ Synonym for "guard". (Compare: content filter, + filtering router.) + + + +Shirey Informational [Page 128] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + 2. (I) /verb/ To process a flow of data and selectively block + passage or permit passage of individual data items according to a + security policy. + + $ filtering router + (I) An internetwork router that selectively prevents the passage + of data packets according to a security policy. (See: guard.) + + Tutorial: A router usually has two or more physical connections to + networks or other systems; and when the router receives a packet + on one of those connections, it forwards the packet on a second + connection. A filtering router does the same; but it first + decides, according to some security policy, whether the packet + should be forwarded at all. The policy is implemented by rules + (packet filters) loaded into the router. The rules mostly involve + values of data packet control fields (especially IP source and + destination addresses and TCP port numbers) [R2179]. A filtering + router may be used alone as a simple firewall or be used as a + component of a more complex firewall. + + $ financial institution + (N) "An establishment responsible for facilitating customer- + initiated transactions or transmission of funds for the extension + of credit or the custody, loan, exchange, or issuance of money." + [SET2] + + $ fingerprint + 1. (I) A pattern of curves formed by the ridges on a fingertip. + (See: biometric authentication. Compare: thumbprint.) + + 2. (D) /PGP/ A hash result ("key fingerprint") used to + authenticate a public key or other data. [PGP] + + Deprecated Definition: IDOCs SHOULD NOT use this term with + definition 2, and SHOULD NOT use this term as a synonym for "hash + result" of *any* kind. Either use would mix concepts in a + potentially misleading way. + + $ FIPS + (N) See: Federal Information Processing Standards. + + $ FIPS PUB 140 + (N) The U.S. Government standard [FP140] for security requirements + to be met by a cryptographic module when the module is used to + protect unclassified information in computer and communication + systems. (See: Common Criteria, FIPS, Federal Standard 1027.) + + + + + +Shirey Informational [Page 129] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Tutorial: The standard specifies four increasing levels (from + "Level 1" to "Level 4") of requirements to cover a wide range of + potential applications and environments. The requirements address + basic design and documentation, module interfaces, authorized + roles and services, physical security, software security, + operating system security, key management, cryptographic + algorithms, electromagnetic interference and electromagnetic + compatibility (EMI/EMC), and self-testing. NIST and the Canadian + Communication Security Establishment jointly certify modules. + + $ FIREFLY + (O) /U.S. Government/ "Key management protocol based on public-key + cryptography." [C4009] + + $ firewall + 1. (I) An internetwork gateway that restricts data communication + traffic to and from one of the connected networks (the one said to + be "inside" the firewall) and thus protects that network's system + resources against threats from the other network (the one that is + said to be "outside" the firewall). (See: guard, security + gateway.) + + 2. (O) A device or system that controls the flow of traffic + between networks using differing security postures. [SP41] + + Tutorial: A firewall typically protects a smaller, secure network + (such as a corporate LAN, or even just one host) from a larger + network (such as the Internet). The firewall is installed at the + point where the networks connect, and the firewall applies policy + rules to control traffic that flows in and out of the protected + network. + + A firewall is not always a single computer. For example, a + firewall may consist of a pair of filtering routers and one or + more proxy servers running on one or more bastion hosts, all + connected to a small, dedicated LAN (see: buffer zone) between the + two routers. The external router blocks attacks that use IP to + break security (IP address spoofing, source routing, packet + fragments), while proxy servers block attacks that would exploit a + vulnerability in a higher-layer protocol or service. The internal + router blocks traffic from leaving the protected network except + through the proxy servers. The difficult part is defining criteria + by which packets are denied passage through the firewall, because + a firewall not only needs to keep unauthorized traffic (i.e., + intruders) out, but usually also needs to let authorized traffic + pass both in and out. + + + + + +Shirey Informational [Page 130] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ firmware + (I) Computer programs and data stored in hardware -- typically in + read-only memory (ROM) or programmable read-only memory (PROM) -- + such that the programs and data cannot be dynamically written or + modified during execution of the programs. (See: hardware, + software.) + + $ FIRST + (N) See: Forum of Incident Response and Security Teams. + + $ flaw + 1. (I) An error in the design, implementation, or operation of an + information system. A flaw may result in a vulnerability. + (Compare: vulnerability.) + + 2. (D) "An error of commission, omission, or oversight in a system + that allows protection mechanisms to be bypassed." [NCSSG] + (Compare: vulnerability. See: brain-damaged.) + + Deprecated Definition: IDOCs SHOULD NOT use this term with + definition 2; not every flaw is a vulnerability. + + $ flaw hypothesis methodology + (I) An evaluation or attack technique in which specifications and + documentation for a system are analyzed to hypothesize flaws in + the system. The list of hypothetical flaws is prioritized on the + basis of the estimated probability that a flaw exists and, + assuming it does, on the ease of exploiting it and the extent of + control or compromise it would provide. The prioritized list is + used to direct a penetration test or attack against the system. + [NCS04] (See: fault tree, flaw.) + + $ flooding + 1. (I) An attack that attempts to cause a failure in a system by + providing more input than the system can process properly. (See: + denial of service, fairness. Compare: jamming.) + + Tutorial: Flooding uses "overload" as a type of "obstruction" + intended to cause "disruption". + + 2. (I) The process of delivering data or control messages to every + node of a network. (RFC 3753) + + $ flow analysis + (I) An analysis performed on a nonprocedural, formal, system + specification that locates potential flows of information between + system variables. By assigning security levels to the variables, + the analysis can find some types of covert channels. [Huff] + + + +Shirey Informational [Page 131] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ flow control + 1. (I) /data security/ A procedure or technique to ensure that + information transfers within a system are not made from one + security level to another security level, and especially not from + a higher level to a lower level. [Denns] (See: covert channel, + confinement property, information flow policy, simple security + property.) + + 2. (O) /data security/ "A concept requiring that information + transfers within a system be controlled so that information in + certain types of objects cannot, via any channel within the + system, flow to certain other types of objects." [NCSSG] + + $ For Official Use Only (FOUO) + (O) /U.S. DoD/ A U.S. Government designation for information that + has not been given a security classification pursuant to the + criteria of an Executive Order dealing with national security, but + which may be withheld from the public because disclosure would + cause a foreseeable harm to an interest protected by one of the + exemptions stated in the Freedom of Information Act (Section 552 + of title 5, United States Code). (See: security label, security + marking. Compare: classified.) + + $ formal + (I) Expressed in a restricted syntax language with defined + semantics based on well-established mathematical concepts. [CCIB] + (Compare: informal, semiformal.) + + $ formal access approval + (O) /U.S. Government/ Documented approval by a data owner to allow + access to a particular category of information in a system. (See: + category.) + + $ Formal Development Methodology + (O) See: Ina Jo. + + $ formal model + (I) A security model that is formal. Example: Bell-LaPadula model. + [Land] (See: formal, security model.) + + $ formal proof + (I) "A complete and convincing mathematical argument, presenting + the full logical justification for each step in the proof, for the + truth of a theorem or set of theorems." [NCSSG] + + $ formal specification + (I) A precise description of the (intended) behavior of a system, + usually written in a mathematical language, sometimes for the + + + +Shirey Informational [Page 132] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + purpose of supporting formal verification through a correctness + proof. [Huff] (See: Affirm, Gypsy, HDM, Ina Jo.) (See: formal.) + + Tutorial: A formal specification can be written at any level of + detail but is usually a top-level specification. + + $ formal top-level specification + (I) "A top-level specification that is written in a formal + mathematical language to allow theorems showing the correspondence + of the system specification to its formal requirements to be + hypothesized and formally proven." [NCS04] (See: formal + specification.) + + $ formulary + (I) A technique for enabling a decision to grant or deny access to + be made dynamically at the time the access is attempted, rather + than earlier when an access control list or ticket is created. + + $ FORTEZZA(trademark) + (O) A registered trademark of NSA, used for a family of + interoperable security products that implement a NIST/NSA-approved + suite of cryptographic algorithms for digital signature, hash, + encryption, and key exchange. The products include a PC card + (which contains a CAPSTONE chip), and compatible serial port + modems, server boards, and software implementations. + + $ Forum of Incident Response and Security Teams (FIRST) + (N) An international consortium of CSIRTs (e.g., CIAC) that work + together to handle computer security incidents and promote + preventive activities. (See: CSIRT, security incident.) + + Tutorial: FIRST was founded in 1990 and, as of July 2004, had more + than 100 members spanning the globe. Its mission includes: + - Provide members with technical information, tools, methods, + assistance, and guidance. + - Coordinate proactive liaison activities and analytical support. + - Encourage development of quality products and services. + - Improve national and international information security for + governments, private industry, academia, and the individual. + - Enhance the image and status of the CSIRT community. + + $ forward secrecy + (I) See: perfect forward secrecy. + + $ FOUO + (O) See: For Official Use Only. + + + + + +Shirey Informational [Page 133] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ FPKI + (O) See: Federal Public-Key Infrastructure. + + $ fraggle attack + (D) /slang/ A synonym for "smurf attack". + + Deprecated Term: It is likely that other cultures use different + metaphors for this concept. Therefore, to avoid international + misunderstanding, IDOCs SHOULD NOT use this term. + + Derivation: The Fraggles are a fictional race of small humanoids + (represented as hand puppets in a children's television series, + "Fraggle Rock") that live underground. + + $ frequency hopping + (N) Repeated switching of frequencies during radio transmission + according to a specified algorithm. [C4009] (See: spread + spectrum.) + + Tutorial: Frequency hopping is a TRANSEC technique to minimize the + potential for unauthorized interception or jamming. + + $ fresh + (I) Recently generated; not replayed from some earlier interaction + of the protocol. + + Usage: Describes data contained in a PDU that is received and + processed for the first time. (See: liveness, nonce, replay + attack.) + + $ FTP + (I) See: File Transfer Protocol. + + $ gateway + (I) An intermediate system (interface, relay) that attaches to two + (or more) computer networks that have similar functions but + dissimilar implementations and that enables either one-way or two- + way communication between the networks. (See: bridge, firewall, + guard, internetwork, proxy server, router, and subnetwork.) + + Tutorial: The networks may differ in any of several aspects, + including protocols and security mechanisms. When two computer + networks differ in the protocol by which they offer service to + hosts, a gateway may translate one protocol into the other or + otherwise facilitate interoperation of hosts (see: Internet + Protocol). In theory, gateways between computer networks are + conceivable at any OSIRM layer. In practice, they usually operate + + + + +Shirey Informational [Page 134] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + at OSIRM Layer 2 (see: bridge), 3 (see: router), or 7 (see: proxy + server). + + $ GCA + (O) See: geopolitical certificate authority. + + $ GDOI + (O) See: Group Domain of Interpretation. + + $ GeldKarte + (O) A smartcard-based, electronic money system that is maintained + by the German banking industry, incorporates cryptography, and can + be used to make payments via the Internet. (See: IOTP.) + + $ GeneralizedTime + (N) The ASN.1 data type "GeneralizedTime" (ISO 8601) contains a + calendar date (YYYYMMDD) and a time of day, which is either (a) + the local time, (b) the Coordinated Universal Time, or (c) both + the local time and an offset that enables Coordinated Universal + Time to be calculated. (See: Coordinated Universal Time. Compare: + UTCTime.) + + $ Generic Security Service Application Program Interface (GSS-API) + (I) An Internet Standard protocol [R2743] that specifies calling + conventions by which an application (typically another + communication protocol) can obtain authentication, integrity, and + confidentiality security services independently of the underlying + security mechanisms and technologies, thus enabling the + application source code to be ported to different environments. + (Compare: EAP, SASL.) + + Tutorial: "A GSS-API caller accepts tokens provided to it by its + local GSS-API implementation and transfers the tokens to a peer on + a remote system; that peer passes the received tokens to its local + GSS-API implementation for processing. The security services + available through GSS-API in this fashion are implementable (and + have been implemented) over a range of underlying mechanisms based + on [symmetric] and [asymmetric cryptography]." [R2743] + + $ geopolitical certificate authority (GCA) + (O) /SET/ In a SET certification hierarchy, an optional level that + is certified by a BCA and that may certify cardholder CAs, + merchant CAs, and payment gateway CAs. Using GCAs enables a brand + to distribute responsibility for managing certificates to + geographic or political regions, so that brand policies can vary + between regions as needed. + + + + + +Shirey Informational [Page 135] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ GIG + (O) See: Global Information Grid. + + $ Global Information Grid (GIG) + (O) /U.S. DoD/ The GIG is "a globally interconnected, end-to-end + set of information capabilities, associated processes and + personnel for collecting, processing, storing, disseminating, and + managing information on demand to war fighters, policy makers, and + support personnel." [IATF] Usage: Formerly referred to as the DII. + + $ good engineering practice(s) + (N) A term used to specify or characterize design, implementation, + installation, or operating practices for an information system, + when a more explicit specification is not possible. Generally + understood to refer to the state of the engineering art for + commercial systems that have problems and solutions equivalent to + the system in question. + + $ granularity + 1. (N) /access control/ Relative fineness to which an access + control mechanism can be adjusted. + + 2. (N) /data security/ "The size of the smallest protectable unit + of information" in a trusted system. [Huff] + + $ Green Book + (D) /slang/ Synonym for "Defense Password Management Guideline" + [CSC2]. + + Deprecated Term: Except as an explanatory appositive, IDOCs SHOULD + NOT use this term, regardless of the associated definition. + Instead, use the full proper name of the document or, in + subsequent references, a conventional abbreviation. (See: Rainbow + Series.) + + Deprecated Usage: To improve international comprehensibility of + Internet Standards and the Internet Standards Process, IDOCs + SHOULD NOT use "cute" synonyms. No matter how clearly understood + or popular a nickname may be in one community, it is likely to + cause confusion or offense in others. For example, several other + information system standards also are called "the Green Book"; the + following are some examples: + - Each volume of 1992 ITU-T (known at that time as CCITT) + standards. + - "PostScript Language Program Design", Adobe Systems, Addison- + Wesley, 1988. + - IEEE 1003.1 POSIX Operating Systems Interface. + + + + +Shirey Informational [Page 136] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + - "Smalltalk-80: Bits of History, Words of Advice", Glenn + Krasner, Addison-Wesley, 1983. + - "X/Open Compatibility Guide". + - A particular CD-ROM format developed by Phillips. + + $ Group Domain of Interpretation (GDOI) + (I) An ISAKMP/IKE domain of interpretation for group key + management; i.e., a phase 2 protocol in ISAKMP. [R3547] (See: + secure multicast.) + + Tutorial: In this group key management model that extends the + ISAKMP standard, the protocol is run between a group member and a + "group controller/key server", which establishes security + associations [R4301] among authorized group members. The GDOI + protocol is itself protected by an ISAKMP phase 1 association. + + For example, multicast applications may use ESP to protect their + data traffic. GDOI carries the needed security association + parameters for ESP. In this way, GDOI supports multicast ESP with + group authentication of ESP packets using a shared, group key. + + $ group identity + (I) See: secondary definition under "identity". + + $ group security association + (I) "A bundling of [security associations] (SAs) that together + define how a group communicates securely. The [group SA] may + include a registration protocol SA, a rekey protocol SA, and one + or more data security protocol SAs." [R3740] + + $ GSS-API + (I) See: Generic Security Service Application Program Interface. + + $ guard + (I) A computer system that (a) acts as gateway between two + information systems operating under different security policies + and (b) is trusted to mediate information data transfers between + the two. (See: controlled interface, cross-domain solution, + domain, filter. Compare: firewall.) + + Usage: Frequently understood to mean that one system is operating + at a higher security level than the other, and that the gateway's + purpose is to prevent unauthorized disclosure of data from the + higher system to the lower. However, the purpose might also be to + protect the data integrity, availability, or general system + integrity of one system from threats posed by connecting to the + other system. The mediation may be entirely automated or may + involve "reliable human review". + + + +Shirey Informational [Page 137] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ guest login + (I) See: anonymous login. + + $ GULS + (I) Generic Upper Layer Security service element (ISO 11586), a + five-part standard for the exchange of security information and + security-transformation functions that protect confidentiality and + integrity of application data. + + $ Gypsy verification environment + (O) A methodology, language, and integrated set of software tools + developed at the University of Texas for specifying, coding, and + verifying software to produce correct and reliable programs. + [Cheh] + + $ H field + (D) See: Deprecated Usage under "Handling Restrictions field". + + $ hack + 1a. (I) /verb/ To work on something, especially to program a + computer. (See: hacker.) + + 1b. (I) /verb/ To do some kind of mischief, especially to play a + prank on, or penetrate, a system. (See: hacker, cracker.) + + 2. (I) /noun/ An item of completed work, or a solution for a + problem, that is non-generalizable, i.e., is very specific to the + application area or problem being solved. + + Tutorial: Often, the application area or problem involves computer + programming or other use of a computer. Characterizing something + as a hack can be a compliment, such as when the solution is + minimal and elegant; or it can be derogatory, such as when the + solution fixes the problem but leaves the system in an + unmaintainable state. + + See [Raym] for several other meanings of this term and also + definitions of several derivative terms. + + $ hacker + 1. (I) Someone with a strong interest in computers, who enjoys + learning about them, programming them, and experimenting and + otherwise working with them. (See: hack. Compare: adversary, + cracker, intruder.) + + Usage: This first definition is the original meaning of the term + (circa 1960); it then had a neutral or positive connotation of + "someone who figures things out and makes something cool happen". + + + +Shirey Informational [Page 138] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + 2. (O) "An individual who spends an inordinate amount of time + working on computer systems for other than professional purposes." + [NCSSG] + + 3. (D) Synonym for "cracker". + + Deprecated Usage: Today, the term is frequently (mis)used + (especially by journalists) with definition 3. + + $ handle + 1. (I) /verb/ Perform processing operations on data, such as + receive and transmit, collect and disseminate, create and delete, + store and retrieve, read and write, and compare. (See: access.) + + 2. (I) /noun/ An online pseudonym, particularly one used by a + cracker; derived from citizens' band radio culture. + + $ handling restriction + (I) A type of access control other than (a) the rule-based + protections of mandatory access control and (b) the identity-based + protections of discretionary access control; usually involves + administrative security. + + $ Handling Restrictions field + (I) A 16-bit field that specifies a control and release marking in + the security option (option type 130) of IP's datagram header + format. The valid field values are alphanumeric digraphs assigned + by the U.S. Government, as specified in RFC 791. + + Deprecated Abbreviation: IDOCs SHOULD NOT use the abbreviation "H + field" because it is potentially ambiguous. Instead, use "Handling + Restrictions field". + + $ handshake + (I) Protocol dialogue between two systems for identifying and + authenticating themselves to each other, or for synchronizing + their operations with each other. + + $ Handshake Protocol + (I) /TLS/ The TLS Handshake Protocol consists of three parts + (i.e., subprotocols) that enable peer entities to agree upon + security parameters for the record layer, authenticate themselves + to each other, instantiate negotiated security parameters, and + report error conditions to each other. [R4346] + + + + + + + +Shirey Informational [Page 139] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ harden + (I) To protect a system by configuring it to operate in a way that + eliminates or mitigates known vulnerabilities. Example: [RSCG]. + (See: default account.) + + $ hardware + (I) The material physical components of an information system. + (See: firmware, software.) + + $ hardware error + (I) /threat action/ See: secondary definitions under "corruption", + "exposure", and "incapacitation". + + $ hardware token + See: token. + + $ hash code + (D) Synonym for "hash result" or "hash function". + + Deprecated Term: IDOCs SHOULD NOT use this term; it mixes concepts + in a potentially misleading way. A hash result is not a "code", + and a hash function does not "encode" in any sense defined by this + glossary. (See: hash value, message digest.) + + $ hash function + 1. (I) A function H that maps an arbitrary, variable-length bit + string, s, into a fixed-length string, h = H(s) (called the "hash + result"). For most computing applications, it is desirable that + given a string s with H(s) = h, any change to s that creates a + different string s' will result in an unpredictable hash result + H(s') that is, with high probability, not equal to H(s). + + 2. (O) "A (mathematical) function which maps values from a large + (possibly very large) domain into a smaller range. A 'good' hash + function is such that the results of applying the function to a + (large) set of values in the domain will be evenly distributed + (and apparently at random) over the range." [X509] + + Tutorial: A hash function operates on variable-length input (e.g., + a message or a file) and outputs a fixed-length output, which + typically is much shorter than most input values. If the algorithm + is "good" as described in the "O" definition, then the hash + function may be a candidate for use in a security mechanism to + detect accidental changes in data, but not necessarily for a + mechanism to detect changes made by active wiretapping. (See: + Tutorial under "checksum".) + + + + + +Shirey Informational [Page 140] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Security mechanisms require a "cryptographic hash function" (e.g., + MD2, MD4, MD5, SHA-1, Snefru), i.e., a good hash function that + also has the one-way property and one of the two collision-free + properties: + - "One-way property": Given H and a hash result h = H(s), it is + hard (i.e., computationally infeasible, "impossible") to find + s. (Of course, given H and an input s, it must be relatively + easy to compute the hash result H(s).) + - "Weakly collision-free property": Given H and an input s, it is + hard (i.e., computationally infeasible, "impossible") to find a + different input, s', such that H(s) = H(s'). + - "Strongly collision-free property": Given H, it is hard to find + any pair of inputs s and s' such that H(s) = H(s'). + + If H produces a hash result N bits long, then to find an s' where + H(s') = H(s) for a specific given s, the amount of computation + required is O(2**n); i.e., it is necessary to try on the order of + 2 to the power n values of s' before finding a collision. However, + to simply find any pair of values s and s' that collide, the + amount of computation required is only O(2**(n/2)); i.e., after + computing H(s) for 2 to the power n/2 randomly chosen values of s, + the probability is greater than 1/2 that two of those values have + the same hash result. (See: birthday attack.) + + $ hash result + 1. (I) The output of a hash function. (See: hash code, hash value. + Compare: hash value.) + + 2. (O) "The output produced by a hash function upon processing a + message" (where "message" is broadly defined as "a digital + representation of data"). [DSG] + + Usage: IDOCs SHOULD avoid the unusual usage of "message" that is + seen in the "O" definition. + + $ hash value + (D) Synonym for "hash result". + + Deprecated Term: IDOCs SHOULD NOT use this term for the output of + a hash function; the term could easily be confused with "hashed + value", which means the input to a hash function. (See: hash code, + hash result, message digest.) + + $ HDM + (O) See: Hierarchical Development Methodology. + + + + + + +Shirey Informational [Page 141] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ Hierarchical Development Methodology (HDM) + (O) A methodology, language, and integrated set of software tools + developed at SRI International for specifying, coding, and + verifying software to produce correct and reliable programs. + [Cheh] + + $ hierarchical PKI + (I) A PKI architecture based on a certification hierarchy. + (Compare: mesh PKI, trust-file PKI.) + + $ hierarchy management + (I) The process of generating configuration data and issuing + public-key certificates to build and operate a certification + hierarchy. (See: certificate management.) + + $ hierarchy of trust + (D) Synonym for "certification hierarchy". + + Deprecated Term: IDOCs SHOULD NOT use this term; it mixes concepts + in a potentially misleading way. (See: certification hierarchy, + trust, web of trust.) + + $ high-assurance guard + (O) "An oxymoron," said Lt. Gen. William H. Campbell, former U.S. + Army chief information officer, speaking at an Armed Forces + Communications and Electronics Association conference. + + Usage: IDOCs that use this term SHOULD state a definition for it + because the term mixes concepts and could easily be misunderstood. + + $ hijack attack + (I) A form of active wiretapping in which the attacker seizes + control of a previously established communication association. + (See: man-in-the-middle attack, pagejacking, piggyback attack.) + + $ HIPAA + (N) Health Information Portability and Accountability Act of 1996, + a U.S. law (Public Law 104-191) that is intended to protect the + privacy of patients' medical records and other health information + in all forms, and mandates security for that information, + including for its electronic storage and transmission. + + $ HMAC + (I) A keyed hash [R2104] that can be based on any iterated + cryptographic hash (e.g., MD5 or SHA-1), so that the cryptographic + strength of HMAC depends on the properties of the selected + cryptographic hash. (See: [R2202, R2403, R2404].) + + + + +Shirey Informational [Page 142] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Derivation: Hash-based MAC. (Compare: CMAC.) + + Tutorial: Assume that H is a generic cryptographic hash in which a + function is iterated on data blocks of length B bytes. L is the + length of the of hash result of H. K is a secret key of length L + <= K <= B. The values IPAD and OPAD are fixed strings used as + inner and outer padding and defined as follows: IPAD = the byte + 0x36 repeated B times, and OPAD = the byte 0x5C repeated B times. + HMAC is computed by H(K XOR OPAD, H(K XOR IPAD, inputdata)). + + HMAC has the following goals: + - To use available cryptographic hash functions without + modification, particularly functions that perform well in + software and for which software is freely and widely available. + - To preserve the original performance of the selected hash + without significant degradation. + - To use and handle keys in a simple way. + - To have a well-understood cryptographic analysis of the + strength of the mechanism based on reasonable assumptions about + the underlying hash function. + - To enable easy replacement of the hash function in case a + faster or stronger hash is found or required. + + $ honey pot + (N) A system (e.g., a web server) or system resource (e.g., a file + on a server) that is designed to be attractive to potential + crackers and intruders, like honey is attractive to bears. (See: + entrapment.) + + Usage: It is likely that other cultures use different metaphors + for this concept. Therefore, to avoid international + misunderstanding, an IDOC SHOULD NOT use this term without + providing a definition for it. (See: Deprecated Usage under "Green + Book".) + + $ host + 1. (I) /general/ A computer that is attached to a communication + subnetwork or internetwork and can use services provided by the + network to exchange data with other attached systems. (See: end + system. Compare: server.) + + 2. (I) /IPS/ A networked computer that does not forward IP packets + that are not addressed to the computer itself. (Compare: router.) + + Derivation: As viewed by its users, a host "entertains" them, + providing Application-Layer services or access to other computers + attached to the network. However, even though some traditional + peripheral service devices, such as printers, can now be + + + +Shirey Informational [Page 143] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + independently connected to networks, they are not usually called + hosts. + + $ HTML + (I) See: Hypertext Markup Language. + + $ HTTP + (I) See: Hypertext Transfer Protocol. + + $ https + (I) When used in the first part of a URL (the part that precedes + the colon and specifies an access scheme or protocol), this term + specifies the use of HTTP enhanced by a security mechanism, which + is usually SSL. (Compare: S-HTTP.) + + $ human error + (I) /threat action/ See: secondary definitions under "corruption", + "exposure", and "incapacitation". + + $ hybrid encryption + (I) An application of cryptography that combines two or more + encryption algorithms, particularly a combination of symmetric and + asymmetric encryption. Examples: digital envelope, MSP, PEM, PGP. + (Compare: superencryption.) + + Tutorial: Asymmetric algorithms require more computation than + equivalently strong symmetric ones. Thus, asymmetric encryption is + not normally used for data confidentiality except to distribute a + symmetric key in a hybrid encryption scheme, where the symmetric + key is usually very short (in terms of bits) compared to the data + file it protects. (See: bulk key.) + + $ hyperlink + (I) In hypertext or hypermedia, an information object (such as a + word, a phrase, or an image, which usually is highlighted by color + or underscoring) that points (i.e., indicates how to connect) to + related information that is located elsewhere and can be retrieved + by activating the link (e.g., by selecting the object with a mouse + pointer and then clicking). + + $ hypermedia + (I) A generalization of hypertext; any media that contain + hyperlinks that point to material in the same or another data + object. + + + + + + + +Shirey Informational [Page 144] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ hypertext + (I) A computer document, or part of a document, that contains + hyperlinks to other documents; i.e., text that contains active + pointers to other text. Usually written in HTML and accessed using + a web browser. (See: hypermedia.) + + $ Hypertext Markup Language (HTML) + (I) A platform-independent system of syntax and semantics (RFC + 1866) for adding characters to data files (particularly text + files) to represent the data's structure and to point to related + data, thus creating hypertext for use in the World Wide Web and + other applications. (Compare: XML.) + + $ Hypertext Transfer Protocol (HTTP) + (I) A TCP-based, Application-Layer, client-server, Internet + protocol (RFC 2616) that is used to carry data requests and + responses in the World Wide Web. (See: hypertext.) + + $ IAB + (I) See: Internet Architecture Board. + + $ IANA + (I) See: Internet Assigned Numbers Authority. + + $ IATF + (O) See: Information Assurance Technical Framework. + + $ ICANN + (I) See: Internet Corporation for Assigned Names and Numbers. + + $ ICMP + (I) See: Internet Control Message Protocol. + + $ ICMP flood + (I) A denial-of-service attack that sends a host more ICMP echo + request ("ping") packets than the protocol implementation can + handle. (See: flooding, smurf.) + + $ ICRL + (N) See: indirect certificate revocation list. + + $ IDEA + (N) See: International Data Encryption Algorithm. + + $ identification + (I) An act or process that presents an identifier to a system so + that the system can recognize a system entity and distinguish it + from other entities. (See: authentication.) + + + +Shirey Informational [Page 145] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ identification information + (D) Synonym for "identifier"; synonym for "authentication + information". (See: authentication, identifying information.) + + Deprecated Term: IDOCs SHOULD NOT use this term as a synonym for + either of those terms; this term (a) is not as precise as they are + and (b) mixes concepts in a potentially misleading way. Instead, + use "identifier" or "authentication information", depending on + what is meant. + + $ Identification Protocol + (I) A client-server Internet protocol [R1413] for learning the + identity of a user of a particular TCP connection. + + Tutorial: Given a TCP port number pair, the server returns a + character string that identifies the owner of that connection on + the server's system. The protocol does not provide an + authentication service and is not intended for authorization or + access control. At best, it provides additional auditing + information with respect to TCP. + + $ identifier + (I) A data object -- often, a printable, non-blank character + string -- that definitively represents a specific identity of a + system entity, distinguishing that identity from all others. + (Compare: identity.) + + Tutorial: Identifiers for system entities must be assigned very + carefully, because authenticated identities are the basis for + other security services, such as access control service. + + $ identifier credential + 1. (I) See: /authentication/ under "credential". + + 2. (D) Synonym for "signature certificate". + + Usage: IDOCs that use this term SHOULD state a definition for it + because the term is used in many ways and could easily be + misunderstood. + + $ identifying information + (D) Synonym for "identifier"; synonym for "authentication + information". (See: authentication, identification information.) + + Deprecated Term: IDOCs SHOULD NOT use this term as a synonym for + either of those terms; this term (a) is not as precise as they are + and (b) mixes concepts in a potentially misleading way. Instead, + + + + +Shirey Informational [Page 146] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + use "identifier" or "authentication information", depending on + what is meant. + + $ identity + (I) The collective aspect of a set of attribute values (i.e., a + set of characteristics) by which a system user or other system + entity is recognizable or known. (See: authenticate, registration. + Compare: identifier.) + + Usage: An IDOC MAY apply this term to either a single entity or a + set of entities. If an IDOC involves both meanings, the IDOC + SHOULD use the following terms and definitions to avoid ambiguity: + - "Singular identity": An identity that is registered for an + entity that is one person or one process. + - "Shared identity": An identity that is registered for an entity + that is a set of singular entities (1) in which each member is + authorized to assume the identity individually and (2) for + which the registering system maintains a record of the singular + entities that comprise the set. In this case, we would expect + each member entity to be registered with a singular identity + before becoming associated with the shared identity. + - "Group identity": An identity that is registered for an entity + (1) that is a set of entities (2) for which the registering + system does not maintain a record of singular entities that + comprise the set. + + Tutorial: When security services are based on identities, two + properties are desirable for the set of attributes used to define + identities: + - The set should be sufficient to distinguish each entity from + all other entities, i.e., to represent each entity uniquely. + - The set should be sufficient to distinguish each identity from + any other identities of the same entity. + + The second property is needed if a system permits an entity to + register two or more concurrent identities. Having two or more + identities for the same entity implies that the entity has two + separate justifications for registration. In that case, the set of + attributes used for identities must be sufficient to represent + multiple identities for a single entity. + + Having two or more identities registered for the same entity is + different from concurrently associating two different identifiers + with the same identity, and also is different from a single + identity concurrently accessing the system in two different roles. + (See: principal, role-based access control.) + + + + + +Shirey Informational [Page 147] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + When an identity of a user is being registered in a system, the + system may require presentation of evidence that proves the + identity's authenticity (i.e., that the user has the right to + claim or use the identity) and its eligibility (i.e., that the + identity is qualified to be registered and needs to be + registered). + + The following diagram illustrates how this term relates to some + other terms in a PKI system: authentication information, + identifier, identifier credential, registration, registered user, + subscriber, and user. + + Relationships: === one-to-one, ==> one-to-many, <=> many-to-many. + +- - - - - - - - - - - - - - - - - - - - - - - - - - + + | PKI System | + + - - - - + | +------------------+ +-------------------------+ | + | User, | | |Subscriber, i.e., | | Identity of Subscriber | | + |i.e., one| | | Registered User, | | is system-unique | | + | of the | | | is system-unique | | +---------------------+ | | + |following| | | +--------------+ | | | Subscriber | | | + | | | | | User's core | | | | Identity's | | | + | +-----+ |===| | Registration | |==>| | Registration data | | | + | |human| | | | | data, i.e., | | | |+-------------------+| | | + | |being| | | | | an entity's | | | || same core data || | | + | +-----+ | | | |distinguishing|========|for all Identities || | | + | or | | | | attribute | | | || of the same User || | | + | +-----+ | | | | values | | +===|+-------------------+| | | + | |auto-| | | | +--------------+ | | | +---------------------+ | | + | |mated| | | +------------------+ | +------------|------------+ | + | |pro- | | | | +=======+ | | + | |cess | | | +-------v----|----------------------|------------+ | + | +-----+ | | | +----------v---+ +------------v----------+ | | + | or | | | |Authentication|<===>|Identifier of Identity | | | + |+-------+| | | | Information | | is system-unique | | | + || a set || | | +--------------+ +-----------------------+ | | + || of || | | Identifier Credential that associates unit of | | + || either|| | | Authentication Information with the Identifier | | + |+-------+| | +------------------------------------------------+ | + + - - - - + + - - - - - - - - - - - - - - - - - - - - - - - - - -+ + + $ identity-based security policy + (I) "A security policy based on the identities and/or attributes + of users, a group of users, or entities acting on behalf of the + users and the resources/objects being accessed." [I7498-2] (See: + rule-based security policy.) + + + + + + +Shirey Informational [Page 148] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ identity proofing + (I) A process that vets and verifies the information that is used + to establish the identity of a system entity. (See: registration.) + + $ IDOC + (I) An abbreviation used in this Glossary to refer to a document + or other item of written material that is generated in the + Internet Standards Process (RFC 2026), i.e., an RFC, an Internet- + Draft, or some other item of discourse. + + Deprecated Usage: This abbreviation SHOULD NOT be used in an IDOC + unless it is first defined in the IDOC because the abbreviation + was invented for this Glossary and is not widely known. + + $ IDS + (I) See: intrusion detection system. + + $ IEEE + (N) See: Institute of Electrical and Electronics Engineers, Inc. + + $ IEEE 802.10 + (N) An IEEE committee developing security standards for LANs. + (See: SILS.) + + $ IEEE P1363 + (N) An IEEE working group, Standard for Public-Key Cryptography, + engaged in developing a comprehensive reference standard for + asymmetric cryptography. Covers discrete logarithm (e.g., DSA), + elliptic curve, and integer factorization (e.g., RSA); and covers + key agreement, digital signature, and encryption. + + $ IESG + (I) See: Internet Engineering Steering Group. + + $ IETF + (I) See: Internet Engineering Task Force. + + $ IKE + (I) See: IPsec Key Exchange. + + $ IMAP4 + (I) See: Internet Message Access Protocol, version 4. + + $ IMAP4 AUTHENTICATE + (I) An IMAP4 command (better described as a transaction type, or + subprotocol) by which an IMAP4 client optionally proposes a + mechanism to an IMAP4 server to authenticate the client to the + server and provide other security services. (See: POP3.) + + + +Shirey Informational [Page 149] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Tutorial: If the server accepts the proposal, the command is + followed by performing a challenge-response authentication + protocol and, optionally, negotiating a protection mechanism for + subsequent POP3 interactions. The security mechanisms that are + used by IMAP4 AUTHENTICATE -- including Kerberos, GSS-API, and + S/Key -- are described in [R1731]. + + $ impossible + (O) Cannot be done in any reasonable amount of time. (See: break, + brute force, strength, work factor.) + + $ in the clear + (I) Not encrypted. (See: clear text.) + + $ Ina Jo + (O) A methodology, language, and integrated set of software tools + developed at the System Development Corporation for specifying, + coding, and verifying software to produce correct and reliable + programs. Usage: a.k.a. the Formal Development Methodology. [Cheh] + + $ incapacitation + (I) A type of threat action that prevents or interrupts system + operation by disabling a system component. (See: disruption.) + + Usage: This type of threat action includes the following subtypes: + - "Malicious logic": In context of incapacitation, any hardware, + firmware, or software (e.g., logic bomb) intentionally + introduced into a system to destroy system functions or + resources. (See: corruption, main entry for "malicious logic", + masquerade, misuse.) + - "Physical destruction": Deliberate destruction of a system + component to interrupt or prevent system operation. + - "Human error": /incapacitation/ Action or inaction that + unintentionally disables a system component. (See: corruption, + exposure.) + - "Hardware or software error": /incapacitation/ Error that + unintentionally causes failure of a system component and leads + to disruption of system operation. (See: corruption, exposure.) + - "Natural disaster": /incapacitation/ Any "act of God" (e.g., + fire, flood, earthquake, lightning, or wind) that disables a + system component. [FP031 Section 2] + + $ incident + See: security incident. + + $ INCITS + (N) See: "International Committee for Information Technology + Standardization" under "ANSI". + + + +Shirey Informational [Page 150] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ indicator + (N) An action -- either specific, generalized, or theoretical -- + that an adversary might be expected to take in preparation for an + attack. [C4009] (See: "attack sensing, warning, and response". + Compare: message indicator.) + + $ indirect attack + (I) See: secondary definition under "attack". Compare: direct + attack. + + $ indirect certificate revocation list (ICRL) + (N) In X.509, a CRL that may contain certificate revocation + notifications for certificates issued by CAs other than the issuer + (i.e., signer) of the ICRL. + + $ indistinguishability + (I) An attribute of an encryption algorithm that is a + formalization of the notion that the encryption of some string is + indistinguishable from the encryption of an equal-length string of + nonsense. (Compare: semantic security.) + + $ inference + 1. (I) A type of threat action that reasons from characteristics + or byproducts of communication and thereby indirectly accesses + sensitive data, but not necessarily the data contained in the + communication. (See: traffic analysis, signal analysis.) + + 2. (I) A type of threat action that indirectly gains unauthorized + access to sensitive information in a database management system by + correlating query responses with information that is already + known. + + $ inference control + (I) Protection of data confidentiality against inference attack. + (See: traffic-flow confidentiality.) + + Tutorial: A database management system containing N records about + individuals may be required to provide statistical summaries about + subsets of the population, while not revealing sensitive + information about a single individual. An attacker may try to + obtain sensitive information about an individual by isolating a + desired record at the intersection of a set of overlapping + queries. A system can attempt to prevent this by restricting the + size and overlap of query sets, distorting responses by rounding + or otherwise perturbing database values, and limiting queries to + random samples. However, these techniques may be impractical to + implement or use, and no technique is totally effective. For + example, restricting the minimum size of a query set -- that is, + + + +Shirey Informational [Page 151] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + not responding to queries for which there are fewer than K or more + than N-K records that satisfy the query -- usually cannot prevent + unauthorized disclosure. An attacker can pad small query sets with + extra records, and then remove the effect of the extra records. + The formula for identifying the extra records is called the + "tracker". [Denns] + + $ INFOCON + (O) See: information operations condition + + $ informal + (N) Expressed in natural language. [CCIB] (Compare: formal, + semiformal.) + + $ information + 1. (I) Facts and ideas, which can be represented (encoded) as + various forms of data. + + 2. (I) Knowledge -- e.g., data, instructions -- in any medium or + form that can be communicated between system entities. + + Tutorial: Internet security could be defined simply as protecting + information in the Internet. However, the perceived need to use + different protective measures for different types of information + (e.g., authentication information, classified information, + collateral information, national security information, personal + information, protocol control information, sensitive compartmented + information, sensitive information) has led to the diversity of + terminology listed in this Glossary. + + $ information assurance + (N) /U.S. Government/ "Measures that protect and defend + information and information systems by ensuring their availability + integrity, authentication, confidentiality, and non-repudiation. + These measures include providing for restoration of information + systems by incorporating protection, detection, and reaction + capabilities." [C4009] + + $ Information Assurance Technical Framework (IATF) + (O) A publicly available document [IATF], developed through a + collaborative effort by organizations in the U.S. Government and + industry, and issued by NSA. Intended for security managers and + system security engineers as a tutorial and reference document + about security problems in information systems and networks, to + improve awareness of tradeoffs among available technology + solutions and of desired characteristics of security approaches + for particular problems. (See: ISO 17799, [SP14].) + + + + +Shirey Informational [Page 152] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ information domain + (O) See: secondary definition under "domain". + + $ information domain security policy + (O) See: secondary definition under "domain". + + $ information flow policy + (N) /formal model/ A triple consisting of a set of security levels + (or their equivalent security labels), a binary operator that maps + each pair of security levels into a security level, and a binary + relation on the set that selects a set of pairs of levels such + that information is permitted to flow from an object of the first + level to an object of the second level. (See: flow control, + lattice model.) + + $ information operations condition (INFOCON) + (O) /U.S. DoD/ A comprehensive defense posture and response based + on the status of information systems, military operations, and + intelligence assessments of adversary capabilities and intent. + (See: threat) + + Derivation: From DEFCON, i.e., defense condition. + + Tutorial: The U.S. DoD defines five INFOCON levels: NORMAL (normal + activity), ALPHA (increased risk of attack), BRAVO (specific risk + of attack), CHARLIE (limited attack), and DELTA (general attack). + + $ information security (INFOSEC) + (N) Measures that implement and assure security services in + information systems, including in computer systems (see: COMPUSEC) + and in communication systems (see: COMSEC). + + $ information system + (I) An organized assembly of computing and communication resources + and procedures -- i.e., equipment and services, together with + their supporting infrastructure, facilities, and personnel -- that + create, collect, record, process, store, transport, retrieve, + display, disseminate, control, or dispose of information to + accomplish a specified set of functions. (See: system entity, + system resource. Compare: computer platform.) + + $ Information Technology Security Evaluation Criteria (ITSEC) + (N) A Standard [ITSEC] jointly developed by France, Germany, the + Netherlands, and the United Kingdom for use in the European Union; + accommodates a wider range of security assurance and functionality + combinations than the TCSEC. Superseded by the Common Criteria. + + + + + +Shirey Informational [Page 153] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ INFOSEC + (I) See: information security. + + $ ingress filtering + (I) A method [R2827] for countering attacks that use packets with + false IP source addresses, by blocking such packets at the + boundary between connected networks. + + Tutorial: Suppose network A of an internet service provider (ISP) + includes a filtering router that is connected to customer network + B, and an attacker in B at IP source address "foo" attempts to + send packets with false source address "bar" into A. The false + address may be either fixed or randomly changing, and it may + either be unreachable or be a forged address that legitimately + exists within either B or some other network C. In ingress + filtering, the ISP's router blocks all inbound packet that arrive + from B with a source address that is not within the range of + legitimately advertised addresses for B. This method does not + prevent all attacks that can originate from B, but the actual + source of such attacks can be more easily traced because the + originating network is known. + + $ initialization value (IV) + (I) /cryptography/ An input parameter that sets the starting state + of a cryptographic algorithm or mode. (Compare: activation data.) + + Tutorial: An IV can be used to synchronize one cryptographic + process with another; e.g., CBC, CFB, and OFB use IVs. An IV also + can be used to introduce cryptographic variance (see: salt) + besides that provided by a key. + + $ initialization vector + (D) /cryptography/ Synonym for "initialization value". + + Deprecated Term: To avoid international misunderstanding, IDOCs + SHOULD NOT use this term in the context of cryptography because + most dictionary definitions of "vector" includes a concept of + direction or magnitude, which are irrelevant to cryptographic use. + + $ insertion + 1. (I) /packet/ See: secondary definition under "stream integrity + service". + + 2. (I) /threat action/ See: secondary definition under + "falsification". + + $ inside attack + (I) See: secondary definition under "attack". Compare: insider. + + + +Shirey Informational [Page 154] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ insider + 1. (I) A user (usually a person) that accesses a system from a + position that is inside the system's security perimeter. (Compare: + authorized user, outsider, unauthorized user.) + + Tutorial: An insider has been assigned a role that has more + privileges to access system resources than do some other types of + users, or can access those resources without being constrained by + some access controls that are applied to outside users. For + example, a salesclerk is an insider who has access to the cash + register, but a store customer is an outsider. + + The actions performed by an insider in accessing the system may be + either authorized or unauthorized; i.e., an insider may act either + as an authorized user or as an unauthorized user. + + 2. (O) A person with authorized physical access to the system. + Example: In this sense, an office janitor is an insider, but a + burglar or casual visitor is not. [NRC98] + + 3. (O) A person with an organizational status that causes the + system or members of the organization to view access requests as + being authorized. Example: In this sense, a purchasing agent is an + insider but a vendor is not. [NRC98] + + $ inspectable space + (O) /EMSEC/ "Three-dimensional space surrounding equipment that + process classified and/or sensitive information within which + TEMPEST exploitation is not considered practical or where legal + authority to identify and/or remove a potential TEMPEST + exploitation exists." [C4009] (Compare: control zone, TEMPEST + zone.) + + $ Institute of Electrical and Electronics Engineers, Inc. (IEEE) + (N) The IEEE is a not-for-profit association of approximately + 300,000 individual members in 150 countries. The IEEE produces + nearly one third of the world's published literature in electrical + engineering, computers, and control technology; holds hundreds of + major, annual conferences; and maintains more than 800 active + standards, with many more under development. (See: SILS.) + + $ integrity + See: data integrity, datagram integrity service, correctness + integrity, source integrity, stream integrity service, system + integrity. + + + + + + +Shirey Informational [Page 155] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ integrity check + (D) A computation that is part of a mechanism to provide data + integrity service or data origin authentication service. (Compare: + checksum.) + + Deprecated Term: IDOCs SHOULD NOT use this term as a synonym for + "cryptographic hash" or "protected checksum". This term + unnecessarily duplicates the meaning of other, well-established + terms; this term only mentions integrity, even though the intended + service may be data origin authentication; and not every checksum + is cryptographically protected. + + $ integrity label + (I) A security label that tells the degree of confidence that may + be placed in the data, and may also tell what countermeasures are + required to be applied to protect the data from alteration and + destruction. (See: integrity. Compare: classification label.) + + $ intelligent threat + (I) A circumstance in which an adversary has the technical and + operational ability to detect and exploit a vulnerability and also + has the demonstrated, presumed, or inferred intent to do so. (See: + threat.) + + $ interception + (I) A type of threat action whereby an unauthorized entity + directly accesses sensitive data while the data is traveling + between authorized sources and destinations. (See: unauthorized + disclosure.) + + Usage: This type of threat action includes the following subtypes: + - "Theft": Gaining access to sensitive data by stealing a + shipment of a physical medium, such as a magnetic tape or disk, + that holds the data. + - "Wiretapping (passive)": Monitoring and recording data that is + flowing between two points in a communication system. (See: + wiretapping.) + - "Emanations analysis": Gaining direct knowledge of communicated + data by monitoring and resolving a signal that is emitted by a + system and that contains the data but was not intended to + communicate the data. (See: emanation.) + + $ interference + (I) /threat action/ See: secondary definition under "obstruction". + + $ intermediate CA + (D) The CA that issues a cross-certificate to another CA. [X509] + (See: cross-certification.) + + + +Shirey Informational [Page 156] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Deprecated Term: IDOCs SHOULD NOT use this term because it is not + widely known and mixes concepts in a potentially misleading way. + For example, suppose that end entity 1 ("EE1) is in one PKI + ("PKI1"), end entity 2 ("EE2) is in another PKI ("PKI2"), and the + root in PKI1 ("CA1") cross-certifies the root CA in PKI2 ("CA2"). + Then, if EE1 constructs the certification path CA1-to-CA2-to-EE2 + to validate a certificate of EE2, conventional English usage would + describe CA2 as being in the "intermediate" position in that path, + not CA1. + + $ internal controls + (I) /COMPUSEC/ Functions, features, and technical characteristics + of computer hardware and software, especially of operating + systems. Includes mechanisms to regulate the operation of a + computer system with regard to access control, flow control, and + inference control. (Compare: external controls.) + + $ International Data Encryption Algorithm (IDEA) + (N) A patented, symmetric block cipher that uses a 128-bit key and + operates on 64-bit blocks. [Schn] (See: symmetric cryptography.) + + $ International Standard + (N) See: secondary definition under "ISO". + + $ International Traffic in Arms Regulations (ITAR) + (O) Rules issued by the U.S. State Department, by authority of the + Arms Export Control Act (22 U.S.C. 2778), to control export and + import of defense articles and defense services, including + information security systems, such as cryptographic systems, and + TEMPEST suppression technology. (See: type 1 product, Wassenaar + Arrangement.) + + $ internet, Internet + 1. (I) /not capitalized/ Abbreviation of "internetwork". + + 2. (I) /capitalized/ The Internet is the single, interconnected, + worldwide system of commercial, governmental, educational, and + other computer networks that share (a) the protocol suite + specified by the IAB (RFC 2026) and (b) the name and address + spaces managed by the ICANN. (See: Internet Layer, Internet + Protocol Suite.) + + Usage: Use with definite article ("the") when using as a noun. For + example, say "My LAN is small, but the Internet is large." Don't + say "My LAN is small, but Internet is large." + + + + + + +Shirey Informational [Page 157] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ Internet Architecture Board (IAB) + (I) A technical advisory group of the ISOC, chartered by the ISOC + Trustees to provide oversight of Internet architecture and + protocols and, in the context of Internet Standards, a body to + which decisions of the IESG may be appealed. Responsible for + approving appointments to the IESG from among nominees submitted + by the IETF nominating committee. (RFC 2026) + + $ Internet Assigned Numbers Authority (IANA) + (I) From the early days of the Internet, the IANA was chartered by + the ISOC and the U.S. Government's Federal Network Council to be + the central coordination, allocation, and registration body for + parameters for Internet protocols. Superseded by ICANN. + + $ Internet Control Message Protocol (ICMP) + (I) An Internet Standard protocol (RFC 792) that is used to report + error conditions during IP datagram processing and to exchange + other information concerning the state of the IP network. + + $ Internet Corporation for Assigned Names and Numbers (ICANN) + (I) The non-profit, private corporation that has assumed + responsibility for the IP address space allocation, protocol + parameter assignment, DNS management, and root server system + management functions formerly performed under U.S. Government + contract by IANA and other entities. + + Tutorial: The IPS, as defined by the IETF and the IESG, contains + numerous parameters, such as Internet addresses, domain names, + autonomous system numbers, protocol numbers, port numbers, + management information base OIDs, including private enterprise + numbers, and many others. The Internet community requires that the + values used in these parameter fields be assigned uniquely. ICANN + makes those assignments as requested and maintains a registry of + the current values. + + ICANN was formed in October 1998, by a coalition of the Internet's + business, technical, and academic communities. The U.S. Government + designated ICANN to serve as the global consensus entity with + responsibility for coordinating four key functions for the + Internet: allocation of IP address space, assignment of protocol + parameters, management of the DNS, and management of the DNS root + server system. + + $ Internet-Draft + (I) A working document of the IETF, its areas, and its working + groups. (RFC 2026) (Compare: RFC.) + + + + + +Shirey Informational [Page 158] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Usage: The term is customarily hyphenated when used either as a + adjective or a noun, even though the latter is not standard + English punctuation. + + Tutorial: An Internet-Draft is not an archival document like an + RFC is. Instead, an Internet-Draft is a preliminary or working + document that is valid for a maximum of six months and may be + updated, replaced, or made obsolete by other documents at any + time. It is inappropriate to use an Internet-Draft as reference + material or to cite it other than as a "work in progress". + Although most of the Internet-Drafts are produced by the IETF, any + interested organization may request to have its working documents + published as Internet-Drafts. + + $ Internet Engineering Steering Group (IESG) + (I) The part of the ISOC responsible for technical management of + IETF activities and administration of the Internet Standards + Process according to procedures approved by the ISOC Trustees. + Directly responsible for actions along the "standards track", + including final approval of specifications as Internet Standards. + Composed of IETF Area Directors and the IETF chairperson, who also + chairs the IESG. (RFC 2026) + + $ Internet Engineering Task Force (IETF) + (I) A self-organized group of people who make contributions to the + development of Internet technology. The principal body engaged in + developing Internet Standards, although not itself a part of the + ISOC. Composed of Working Groups, which are arranged into Areas + (such as the Security Area), each coordinated by one or more Area + Directors. Nominations to the IAB and the IESG are made by a + committee selected at random from regular IETF meeting attendees + who have volunteered. (RFCs 2026, 3935) [R2323] + + $ Internet Key Exchange (IKE) + (I) An Internet, IPsec, key-establishment protocol [R4306] for + putting in place authenticated keying material (a) for use with + ISAKMP and (b) for other security associations, such as in AH and + ESP. + + Tutorial: IKE is based on three earlier protocol designs: ISAKMP, + OAKLEY, and SKEME. + + $ Internet Layer + (I) See: Internet Protocol Suite. + + $ Internet Message Access Protocol, version 4 (IMAP4) + (I) An Internet protocol (RFC 2060) by which a client workstation + can dynamically access a mailbox on a server host to manipulate + + + +Shirey Informational [Page 159] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + and retrieve mail messages that the server has received and is + holding for the client. (See: POP3.) + + Tutorial: IMAP4 has mechanisms for optionally authenticating a + client to a server and providing other security services. (See: + IMAP4 AUTHENTICATE.) + + $ Internet Open Trading Protocol (IOTP) + (I) An Internet protocol [R2801] proposed as a general framework + for Internet commerce, able to encapsulate transactions of various + proprietary payment systems (e.g., GeldKarte, Mondex, SET, Visa + Cash). Provides optional security services by incorporating + various Internet security mechanisms (e.g., MD5) and protocols + (e.g., TLS). + + $ Internet Policy Registration Authority (IPRA) + (I) An X.509-compliant CA that is the top CA of the Internet + certification hierarchy operated under the auspices of the ISOC + [R1422]. (See: /PEM/ under "certification hierarchy".) + + $ Internet Private Line Interface (IPLI) + (O) A successor to the PLI, updated to use TCP/IP and newer + military-grade COMSEC equipment (TSEC/KG-84). The IPLI was a + portable, modular system that was developed for use in tactical, + packet-radio networks. (See: end-to-end encryption.) + + $ Internet Protocol (IP) + (I) An Internet Standard, Internet-Layer protocol that moves + datagrams (discrete sets of bits) from one computer to another + across an internetwork but does not provide reliable delivery, + flow control, sequencing, or other end-to-end services that TCP + provides. IP version 4 (IPv4) is specified in RFC 791, and IP + version 6 (IPv6) is specified in RFC 2460. (See: IP address, + TCP/IP.) + + Tutorial: If IP were used in an OSIRM stack, IP would be placed at + the top of Layer 3, above other Layer 3 protocols in the stack. + + In any IPS stack, IP is always present in the Internet Layer and + is always placed at the top of that layer, on top of any other + protocols that are used in that layer. In some sense, IP is the + only protocol specified for the IPS Internet Layer; other + protocols used there, such as AH and ESP, are just IP variations. + + $ Internet Protocol security + See: IP Security Protocol. + + + + + +Shirey Informational [Page 160] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ Internet Protocol Security Option (IPSO) + (I) Refers to one of three types of IP security options, which are + fields that may be added to an IP datagram for carrying security + information about the datagram. (Compare: IPsec.) + + Deprecated Usage: IDOCs SHOULD NOT use this term without a + modifier to indicate which of the following three types is meant: + - "DoD Basic Security Option" (IP option type 130): Defined for + use on U.S. DoD common-use data networks. Identifies the DoD + classification level at which the datagram is to be protected + and the protection authorities whose rules apply to the + datagram. (A "protection authority" is a National Access + Program (e.g., GENSER, SIOP-ESI, SCI, NSA, Department of + Energy) or Special Access Program that specifies protection + rules for transmission and processing of the information + contained in the datagram.) [R1108] + - "DoD Extended Security Option" (IP option type 133): Permits + additional security labeling information, beyond that present + in the Basic Security Option, to be supplied in the datagram to + meet the needs of registered authorities. [R1108] + - "Common IP Security Option" (CIPSO) (IP option type 134): + Designed by TSIG to carry hierarchic and non-hierarchic + security labels. (Formerly called "Commercial IP Security + Option"; a version 2.3 draft was published 9 March 1993 as an + Internet-Draft but did not advance to RFC form.) [CIPSO] + + $ Internet Protocol Suite (IPS) + (I) The set of network communication protocols that are specified + by the IETF, and approved as Internet Standards by the IESG, + within the oversight of the IAB. (See: OSIRM Security + Architecture. Compare: OSIRM.) + + Usage: This set of protocols is popularly known as "TCP/IP" + because TCP and IP are its most basic and important components. + + For clarity, this Glossary refers to IPS protocol layers by name + and capitalizes those names, and refers to OSIRM protocol layers + by number. + + Tutorial: The IPS does have architectural principles [R1958], but + there is no Internet Standard that defines a layered IPS reference + model like the OSIRM. Still, Internet community literature has + referred (inconsistently) to IPS layers since early in the + Internet's development [Padl]. + + + + + + + +Shirey Informational [Page 161] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + This Glossary treats the IPS as having five protocol layers -- + Application, Transport, Internet, Network Interface, and Network + Hardware (or Network Substrate) -- which are illustrated in the + following diagram: + + OSIRM Layers Examples IPS Layers Examples + ------------------ --------------- --------------- -------------- + Message Format: P2 [X420] Message Format: ARPA (RFC 822) + +----------------+ +-------------+ + |7.Application | P1 [X419] | Application | SMTP (RFC 821) + +----------------+ - - - - - - | | + |6.Presentation | [I8823] | | + +----------------+ - - - - - - | | + |5.Session | [I8327] +-------------+ + +----------------+ - - - - - - | Transport | TCP (RFC 793) + |4.Transport | TP4 [I8073] | | + +----------------+ - - - - - - +-------------+ + |3.Network | CLNP [I8473] | Internet | IP (RFC 791) + | | +-------------+ + | | | Network | IP over IEEE + +----------------+ - - - - - - | Interface | 802 (RFC 1042) + |2.Data Link | +-------------+ + | | LLC [I8802-2] - Network - The IPS does + | | MAC [I8802-3] - Hardware - not include + +----------------+ - (or Network - standards for + |1.Physical | Baseband - Substrate) - this layer. + +----------------+ Signaling [Stal] + - - - - - - + + + The diagram approximates how the five IPS layers align with the + seven OSIRM layers, and it offers examples of protocol stacks that + provide roughly equivalent electronic mail service over a private + LAN that uses baseband signaling. + + - IPS Application Layer: The user runs an application program. + The program selects the data transport service it needs -- + either a sequence of data messages or a continuous stream of + data -- and hands application data to the Transport Layer for + delivery. + + - IPS Transport Layer: This layer divides application data into + packets, adds a destination address to each, and communicates + them end-to-end -- from one application program to another -- + optionally regulating the flow and ensuring reliable (error- + free and sequenced) delivery. + + - IPS Internet Layer: This layer carries transport packets in IP + datagrams. It moves each datagram independently, from its + source computer to its addressed destination computer, routing + + + +Shirey Informational [Page 162] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + the datagram through a sequence of networks and relays and + selecting appropriate network interfaces en route. + + - IPS Network Interface Layer: This layer accepts datagrams for + transmission over a specific network. This layer specifies + interface conventions for carrying IP over OSIRM Layer 3 + protocols and over Media Access Control sublayer protocols of + OSIRM Layer 2. An example is IP over IEEE 802 (RFD 1042). + + - IPS Network Hardware Layer: This layer consists of specific, + physical communication media. However, the IPS does not specify + its own peer-to-peer protocols in this layer. Instead, the + layering conventions specified by the Network Interface Layer + use Layer 2 and Layer 3 protocols that are specified by bodies + other than the IETF. That is, the IPS addresses *inter*-network + functions and does not address *intra*-network functions. + + The two models are most dissimilar in the upper layers, where the + IPS model does not include Session and Presentation layers. + However, this omission causes fewer functional differences between + the models than might be imagined, and the differences have + relatively few security implications: + + - Formal separation of OSIRM Layers 5, 6, and 7 is not needed in + implementations; the functions of these layers sometimes are + mixed in a single software unit, even in protocols in the OSI + suite. + + - Some OSIRM Layer 5 services -- for example, connection + termination -- are built into TCP, and the remaining Layer 5 + and 6 functions are built into IPS Application-Layer protocols + where needed. + + - The OSIRM does not place any security services in Layer 5 (see: + OSIRM Security Architecture). + + - The lack of an explicit Presentation Layer in the IPS sometimes + makes it simpler to implement security in IPS applications. For + example, a primary function of Layer 6 is to convert data + between internal and external forms, using a transfer syntax to + unambiguously encode data for transmission. If an OSIRM + application encrypts data to protect against disclosure during + transmission, the transfer encoding must be done before the + encryption. If an application does encryption, as is done in + OSI message handling and directory service protocols, then + Layer 6 functions must be replicated in Layer 7. [X400, X500]. + + + + + +Shirey Informational [Page 163] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + The two models are most alike at the top of OSIRM Layer 3, where + the OSI Connectionless Network Layer Protocol (CLNP) and the IPS + IP are quite similar. Connection-oriented security services + offered in OSIRM Layer 3 are inapplicable in the IPS, because the + IPS Internet Layer lacks the explicit, connection-oriented service + offered in the OSIRM. + + $ Internet Security Association and Key Management Protocol (ISAKMP) + (I) An Internet IPsec protocol [R2408] to negotiate, establish, + modify, and delete security associations, and to exchange key + generation and authentication data, independent of the details of + any specific key generation technique, key establishment protocol, + encryption algorithm, or authentication mechanism. + + Tutorial: ISAKMP supports negotiation of security associations for + protocols at all IPS layers. By centralizing management of + security associations, ISAKMP reduces duplicated functionality + within each protocol. ISAKMP can also reduce connection setup + time, by negotiating a whole stack of services at once. Strong + authentication is required on ISAKMP exchanges, and a digital + signature algorithm based on asymmetric cryptography is used + within ISAKMP's authentication component. + + ISAKMP negotiations are conducted in two "phases": + - "Phase 1 negotiation". A phase 1 negotiation establishes a + security association to be used by ISAKMP to protect its own + protocol operations. + - "Phase 2 negotiation". A phase 2 negotiation (which is + protected by a security association that was established by a + phase 1 negotiation) establishes a security association to be + used to protect the operations of a protocol other than ISAKMP, + such as ESP. + + $ Internet Society (ISOC) + (I) A professional society concerned with Internet development + (including technical Internet Standards); with how the Internet is + and can be used; and with social, political, and technical issues + that result. The ISOC Board of Trustees approves appointments to + the IAB from among nominees submitted by the IETF nominating + committee. (RFC 2026) + + $ Internet Standard + (I) A specification, approved by the IESG and published as an RFC, + that is stable and well-understood, is technically competent, has + multiple, independent, and interoperable implementations with + substantial operational experience, enjoys significant public + support, and is recognizably useful in some or all parts of the + Internet. (RFC 2026) (Compare: RFC.) + + + +Shirey Informational [Page 164] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Tutorial: The "Internet Standards Process" is an activity of the + ISOC and is organized and managed by the IAB and the IESG. The + process is concerned with all protocols, procedures, and + conventions used in or by the Internet, whether or not they are + part of the IPS. The "Internet Standards Track" has three levels + of increasing maturity: Proposed Standard, Draft Standard, and + Standard. (Compare: ISO, W3C.) + + $ internetwork + (I) A system of interconnected networks; a network of networks. + Usually shortened to "internet". (See: internet, Internet.) + + Tutorial: An internet can be built using OSIRM Layer 3 gateways to + implement connections between a set of similar subnetworks. With + dissimilar subnetworks, i.e., subnetworks that differ in the Layer + 3 protocol service they offer, an internet can be built by + implementing a uniform internetwork protocol (e.g., IP) that + operates at the top of Layer 3 and hides the underlying + subnetworks' heterogeneity from hosts that use communication + services provided by the internet. (See: router.) + + $ intranet + (I) A computer network, especially one based on Internet + technology, that an organization uses for its own internal (and + usually private) purposes and that is closed to outsiders. (See: + extranet, VPN.) + + $ intruder + (I) An entity that gains or attempts to gain access to a system or + system resource without having authorization to do so. (See: + intrusion. Compare: adversary, cracker, hacker.) + + $ intrusion + 1. (I) A security event, or a combination of multiple security + events, that constitutes a security incident in which an intruder + gains, or attempts to gain, access to a system or system resource + without having authorization to do so. (See: IDS.) + + 2. (I) A type of threat action whereby an unauthorized entity + gains access to sensitive data by circumventing a system's + security protections. (See: unauthorized disclosure.) + + Usage: This type of threat action includes the following subtypes: + - "Trespass": Gaining physical access to sensitive data by + circumventing a system's protections. + - "Penetration": Gaining logical access to sensitive data by + circumventing a system's protections. + + + + +Shirey Informational [Page 165] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + - "Reverse engineering": Acquiring sensitive data by + disassembling and analyzing the design of a system component. + - "Cryptanalysis": Transforming encrypted data into plain text + without having prior knowledge of encryption parameters or + processes. (See: main entry for "cryptanalysis".) + + $ intrusion detection + (I) Sensing and analyzing system events for the purpose of + noticing (i.e., becoming aware of) attempts to access system + resources in an unauthorized manner. (See: anomaly detection, IDS, + misuse detection. Compare: extrusion detection.) [IDSAN, IDSSC, + IDSSE, IDSSY] + + Usage: This includes the following subtypes: + - "Active detection": Real-time or near-real-time analysis of + system event data to detect current intrusions, which result in + an immediate protective response. + - "Passive detection": Off-line analysis of audit data to detect + past intrusions, which are reported to the system security + officer for corrective action. (Compare: security audit.) + + $ intrusion detection system (IDS) + 1. (N) A process or subsystem, implemented in software or + hardware, that automates the tasks of (a) monitoring events that + occur in a computer network and (b) analyzing them for signs of + security problems. [SP31] (See: intrusion detection.) + + 2. (N) A security alarm system to detect unauthorized entry. + [DC6/9]. + + Tutorial: Active intrusion detection processes can be either host- + based or network-based: + - "Host-based": Intrusion detection components -- traffic sensors + and analyzers -- run directly on the hosts that they are + intended to protect. + - "Network-based": Sensors are placed on subnetwork components, + and analysis components run either on subnetwork components or + hosts. + + $ invalidity date + (N) An X.509 CRL entry extension that "indicates the date at which + it is known or suspected that the [revoked certificate's private + key] was compromised or that the certificate should otherwise be + considered invalid." [X509]. + + Tutorial: This date may be earlier than the revocation date in the + CRL entry, and may even be earlier than the date of issue of + earlier CRLs. However, the invalidity date is not, by itself, + + + +Shirey Informational [Page 166] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + sufficient for purposes of non-repudiation service. For example, + to fraudulently repudiate a validly generated signature, a private + key holder may falsely claim that the key was compromised at some + time in the past. + + $ IOTP + (I) See: Internet Open Trading Protocol. + + $ IP + (I) See: Internet Protocol. + + $ IP address + (I) A computer's internetwork address that is assigned for use by + IP and other protocols. + + Tutorial: An IP version 4 address (RFC 791) has four 8-bit parts + and is written as a series of four decimal numbers separated by + periods. Example: The address of the host named "rosslyn.bbn.com" + is 192.1.7.10. + + An IP version 6 address (RFC 2373) has eight 16-bit parts and is + written as eight hexadecimal numbers separated by colons. + Examples: 1080:0:0:0:8:800:200C:417A and + FEDC:BA98:7654:3210:FEDC:BA98:7654:3210. + + $ IP Security Option + (I) See: Internet Protocol Security Option. + + $ IP Security Protocol (IPsec) + 1a. (I) The name of the IETF working group that is specifying an + architecture [R2401, R4301] and set of protocols to provide + security services for IP traffic. (See: AH, ESP, IKE, SAD, SPD. + Compare: IPSO.) + + 1b. (I) A collective name for the IP security architecture [R4301] + and associated set of protocols (primarily AH, ESP, and IKE). + + Usage: In IDOCs that use the abbreviation "IPsec", the letters + "IP" SHOULD be in uppercase, and the letters "sec" SHOULD NOT. + + Tutorial: The security services provided by IPsec include access + control service, connectionless data integrity service, data + origin authentication service, protection against replays + (detection of the arrival of duplicate datagrams, within a + constrained window), data confidentiality service, and limited + traffic-flow confidentiality. IPsec specifies (a) security + protocols (AH and ESP), (b) security associations (what they are, + how they work, how they are managed, and associated processing), + + + +Shirey Informational [Page 167] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + (c) key management (IKE), and (d) algorithms for authentication + and encryption. Implementation of IPsec is optional for IP version + 4, but mandatory for IP version 6. (See: transport mode, tunnel + mode.) + + $ IPLI + (I) See: Internet Private Line Interface. + + $ IPRA + (I) See: Internet Policy Registration Authority. + + $ IPS + (I) See: Internet Protocol Suite. + + $ IPsec + (I) See: IP Security Protocol. + + $ IPSO + (I) See: Internet Protocol Security Option. + + $ ISAKMP + (I) See: Internet Security Association and Key Management + Protocol. + + $ ISO + (I) International Organization for Standardization, a voluntary, + non-treaty, non-governmental organization, established in 1947, + with voting members that are designated standards bodies of + participating nations and non-voting observer organizations. + (Compare: ANSI, IETF, ITU-T, W3C.) + + Tutorial: Legally, ISO is a Swiss, non-profit, private + organization. ISO and the IEC (the International Electrotechnical + Commission) form the specialized system for worldwide + standardization. National bodies that are members of ISO or IEC + participate in developing international standards through ISO and + IEC technical committees that deal with particular fields of + activity. Other international governmental and non-governmental + organizations, in liaison with ISO and IEC, also take part. (ANSI + is the U.S. voting member of ISO. ISO is a class D member of ITU- + T.) + + The ISO standards development process has four levels of + increasing maturity: Working Draft (WD), Committee Draft (CD), + Draft International Standard (DIS), and International Standard + (IS). (Compare: "Internet Standards Track" under "Internet + Standard".) In information technology, ISO and IEC have a joint + technical committee, ISO/IEC JTC 1. DISs adopted by JTC 1 are + + + +Shirey Informational [Page 168] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + circulated to national bodies for voting, and publication as an IS + requires approval by at least 75% of the national bodies casting a + vote. + + $ ISO 17799 + (N) An International Standard that is a code of practice, derived + from Part 1 of British Standard 7799, for managing the security of + information systems in an organization. This standard does not + provide definitive or specific material on any security topic. It + provides general guidance on a wide variety of topics, but + typically does not go into depth. (See: IATF, [SP14].) + + $ ISOC + (I) See: Internet Society. + + $ issue + (I) /PKI/ Generate and sign a digital certificate (or a CRL) and, + usually, distribute it and make it available to potential + certificate users (or CRL users). (See: certificate creation.) + + Usage: The term "issuing" is usually understood to refer not only + to creating a digital certificate (or a CRL) but also to making it + available to potential users, such as by storing it in a + repository or other directory or otherwise publishing it. However, + the ABA [DSG] explicitly limits this term to the creation process + and excludes any related publishing or distribution process. + + $ issuer + 1. (I) /certificate, CRL/ The CA that signs a digital certificate + or CRL. + + Tutorial: An X.509 certificate always includes the issuer's name. + The name may include a common name value. + + 2. (O) /payment card, SET/ "The financial institution or its agent + that issues the unique primary account number to the cardholder + for the payment card brand." [SET2] + + Tutorial: The institution that establishes the account for a + cardholder and issues the payment card also guarantees payment for + authorized transactions that use the card in accordance with card + brand regulations and local legislation. [SET1] + + $ ITAR + (O) See: International Traffic in Arms Regulations. + + $ ITSEC + (N) See: Information Technology System Evaluation Criteria. + + + +Shirey Informational [Page 169] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ ITU-T + (N) International Telecommunications Union, Telecommunication + Standardization Sector (formerly "CCITT"), a United Nations treaty + organization that is composed mainly of postal, telephone, and + telegraph authorities of the member countries and that publishes + standards called "Recommendations". (See: X.400, X.500.) + + Tutorial: The Department of State represents the United States. + ITU-T works on many kinds of communication systems. ITU-T + cooperates with ISO on communication protocol standards, and many + Recommendations in that area are also published as an ISO standard + with an ISO name and number. + + $ IV + (I) See: initialization value. + + $ jamming + (N) An attack that attempts to interfere with the reception of + broadcast communications. (See: anti-jam, denial of service. + Compare: flooding.) + + Tutorial: Jamming uses "interference" as a type of "obstruction" + intended to cause "disruption". Jamming a broadcast signal is + typically done by broadcasting a second signal that receivers + cannot separate from the first one. Jamming is mainly thought of + in the context of wireless communication, but also can be done in + some wired technologies, such as LANs that use contention + techniques to share a broadcast medium. + + $ KAK + (D) See: key-auto-key. (Compare: KEK.) + + $ KDC + (I) See: Key Distribution Center. + + $ KEA + (N) See: Key Exchange Algorithm. + + $ KEK + (I) See: key-encrypting key. (Compare: KAK.) + + $ Kerberos + (I) A system developed at the Massachusetts Institute of + Technology that depends on passwords and symmetric cryptography + (DES) to implement ticket-based, peer entity authentication + service and access control service distributed in a client-server + network environment. [R4120, Stei] (See: realm.) + + + + +Shirey Informational [Page 170] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Tutorial: Kerberos was originally developed by Project Athena and + is named for the mythical three-headed dog that guards Hades. The + system architecture includes authentication servers and ticket- + granting servers that function as an ACC and a KDC. + + RFC 4556 describes extensions to the Kerberos specification that + modify the initial authentication exchange between a client and + the KDC. The extensions employ public-key cryptography to enable + the client and KDC to mutually authenticate and establish shared, + symmetric keys that are used to complete the exchange. (See: + PKINIT.) + + $ kernel + (I) A small, trusted part of a system that provides services on + which the other parts of the system depend. (See: security + kernel.) + + $ Kernelized Secure Operating System (KSOS) + (O) An MLS computer operating system, designed to be a provably + secure replacement for UNIX Version 6, and consisting of a + security kernel, non-kernel security-related utility programs, and + optional UNIX application development and support environments. + [Perr] + + Tutorial: KSOS-6 was the implementation on a SCOMP. KSOS-11 was + the implementation by Ford Aerospace and Communications + Corporation on the DEC PDP-11/45 and PDP-11/70 computers. + + $ key + 1a. (I) /cryptography/ An input parameter used to vary a + transformation function performed by a cryptographic algorithm. + (See: private key, public key, storage key, symmetric key, traffic + key. Compare: initialization value.) + + 1b. (O) /cryptography/ Used in singular form as a collective noun + referring to keys or keying material. Example: A fill device can + be used transfer key between two cryptographic devices. + + 2. (I) /anti-jam/ An input parameter used to vary a process that + determines patterns for an anti-jam measure. (See: frequency + hopping, spread spectrum.) + + Tutorial: A key is usually specified as a sequence of bits or + other symbols. If a key value needs to be kept secret, the + sequence of symbols that comprise it should be random, or at least + pseudorandom, because that makes the key harder for an adversary + to guess. (See: brute-force attack, cryptanalysis, strength.) + + + + +Shirey Informational [Page 171] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ key agreement (algorithm or protocol) + 1. (I) A key establishment method (especially one involving + asymmetric cryptography) by which two or more entities, without + prior arrangement except a public exchange of data (such as public + keys), each can generate the same key value. That is, the method + does not send a secret from one entity to the other; instead, both + entities, without prior arrangement except a public exchange of + data, can compute the same secret value, but that value cannot be + computed by other, unauthorized entities. (See: Diffie-Hellman- + Merkle, key establishment, KEA, MQV. Compare: key transport.) + + 2. (O) "A method for negotiating a key value on line without + transferring the key, even in an encrypted form, e.g., the Diffie- + Hellman technique." [X509] (See: Diffie-Hellman-Merkle.) + + 3. (O) "The procedure whereby two different parties generate + shared symmetric keys such that any of the shared symmetric keys + is a function of the information contributed by all legitimate + participants, so that no party [alone] can predetermine the value + of the key." [A9042] + + Example: A message originator and the intended recipient can each + use their own private key and the other's public key with the + Diffie-Hellman-Merkle algorithm to first compute a shared secret + value and, from that value, derive a session key to encrypt the + message. + + $ key authentication + (N) "The assurance of the legitimate participants in a key + agreement [i.e., in a key-agreement protocol] that no non- + legitimate party possesses the shared symmetric key." [A9042] + + $ key-auto-key (KAK) + (D) "Cryptographic logic [i.e., a mode of operation] using + previous key to produce key." [C4009, A1523] (See: CTAK, + /cryptographic operation/ under "mode".) + + Deprecated Term: IDOCs SHOULD NOT use this term; it is neither + well-known nor precisely defined. Instead, use terms associated + with modes that are defined in standards, such as CBC, CFB, and + OFB. + + $ key center + (I) A centralized, key-distribution process (used in symmetric + cryptography), usually a separate computer system, that uses + master keys (i.e., KEKs) to encrypt and distribute session keys + needed by a community of users. + + + + +Shirey Informational [Page 172] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Tutorial: An ANSI standard [A9017] defines two types of key + center: "key distribution center" and "key translation center". + + $ key confirmation + (N) "The assurance [provided to] the legitimate participants in a + key establishment protocol that the [parties that are intended to + share] the symmetric key actually possess the shared symmetric + key." [A9042] + + $ key distribution + (I) A process that delivers a cryptographic key from the location + where it is generated to the locations where it is used in a + cryptographic algorithm. (See: key establishment, key management.) + + $ key distribution center (KDC) + 1. (I) A type of key center (used in symmetric cryptography) that + implements a key-distribution protocol to provide keys (usually, + session keys) to two (or more) entities that wish to communicate + securely. (Compare: key translation center.) + + 2. (N) "COMSEC facility generating and distributing key in + electrical form." [C4009] + + Tutorial: A KDC distributes keys to Alice and Bob, who (a) wish to + communicate with each other but do not currently share keys, (b) + each share a KEK with the KDC, and (c) may not be able to generate + or acquire keys by themselves. Alice requests the keys from the + KDC. The KDC generates or acquires the keys and makes two + identical sets. The KDC encrypts one set in the KEK it shares with + Alice, and sends that encrypted set to Alice. The KDC encrypts the + second set in the KEK it shares with Bob, and either (a) sends + that encrypted set to Alice for her to forward to Bob or (b) sends + it directly to Bob (although the latter option is not supported in + the ANSI standard [A9017]). + + $ key encapsulation + (N) A key recovery technique for storing knowledge of a + cryptographic key by encrypting it with another key and ensuring + that only certain third parties called "recovery agents" can + perform the decryption operation to retrieve the stored key. Key + encapsulation typically permits direct retrieval of a secret key + used to provide data confidentiality. (Compare: key escrow.) + + $ key-encrypting key (KEK) + (I) A cryptographic key that (a) is used to encrypt other keys + (either DEKs or other TEKs) for transmission or storage but (b) + (usually) is not used to encrypt application data. Usage: + Sometimes called "key-encryption key". + + + +Shirey Informational [Page 173] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ key escrow + (N) A key recovery technique for storing knowledge of a + cryptographic key or parts thereof in the custody of one or more + third parties called "escrow agents", so that the key can be + recovered and used in specified circumstances. (Compare: key + encapsulation.) + + Tutorial: Key escrow is typically implemented with split knowledge + techniques. For example, the Escrowed Encryption Standard [FP185] + entrusts two components of a device-unique split key to separate + escrow agents. The agents provide the components only to someone + legally authorized to conduct electronic surveillance of + telecommunications encrypted by that specific device. The + components are used to reconstruct the device-unique key, and it + is used to obtain the session key needed to decrypt + communications. + + $ key establishment (algorithm or protocol) + 1. (I) A procedure that combines the key-generation and key- + distribution steps needed to set up or install a secure + communication association. + + 2. (I) A procedure that results in keying material being shared + among two or more system entities. [A9042, SP56] + + Tutorial: The two basic techniques for key establishment are "key + agreement" and "key transport". + + $ Key Exchange Algorithm (KEA) + (N) A key-agreement method [SKIP, R2773] that is based on the + Diffie-Hellman-Merkle algorithm and uses 1024-bit asymmetric keys. + (See: CAPSTONE, CLIPPER, FORTEZZA, SKIPJACK.) + + Tutorial: KEA was developed by NSA and formerly classified at the + U.S. DoD "Secret" level. On 23 June 1998, the NSA announced that + KEA had been declassified. + + $ key generation + (I) A process that creates the sequence of symbols that comprise a + cryptographic key. (See: key management.) + + $ key generator + 1. (I) An algorithm that uses mathematical rules to + deterministically produce a pseudorandom sequence of cryptographic + key values. + + 2. (I) An encryption device that incorporates a key-generation + mechanism and applies the key to plain text to produce cipher text + + + +Shirey Informational [Page 174] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + (e.g., by exclusive OR-ing (a) a bit-string representation of the + key with (b) a bit-string representation of the plaintext). + + $ key length + (I) The number of symbols (usually stated as a number of bits) + needed to be able to represent any of the possible values of a + cryptographic key. (See: key space.) + + $ key lifetime + 1. (D) Synonym for "cryptoperiod". + + Deprecated Definition: IDOCs SHOULD NOT use this term with + definition 1 because a key's cryptoperiod may be only a part of + the key's lifetime. A key could be generated at some time prior to + when its cryptoperiod begins and might not be destroyed (i.e., + zeroized) until some time after its cryptoperiod ends. + + 2. (O) /MISSI/ An attribute of a MISSI key pair that specifies a + time span that bounds the validity period of any MISSI X.509 + public-key certificate that contains the public component of the + pair. (See: cryptoperiod.) + + $ key loader + (N) Synonym for "fill device". + + $ key loading and initialization facility (KLIF) + (N) A place where ECU hardware is activated after being + fabricated. (Compare: CLEF.) + + Tutorial: Before going to its KLIF, an ECU is not ready to be + fielded, usually because it is not yet able to receive DEKs. The + KLIF employs trusted processes to complete the ECU by installing + needed data such as KEKs, seed values, and, in some cases, + cryptographic software. After KLIF processing, the ECU is ready + for deployment. + + $ key management + 1a. (I) The process of handling keying material during its life + cycle in a cryptographic system; and the supervision and control + of that process. (See: key distribution, key escrow, keying + material, public-key infrastructure.) + + Usage: Usually understood to include ordering, generating, + storing, archiving, escrowing, distributing, loading, destroying, + auditing, and accounting for the material. + + 1b. (O) /NIST/ "The activities involving the handling of + cryptographic keys and other related security parameters (e.g., + + + +Shirey Informational [Page 175] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + IVs, counters) during the entire life cycle of the keys, including + their generation, storage, distribution, entry and use, deletion + or destruction, and archiving." [FP140, SP57] + + 2. (O) /OSIRM/ "The generation, storage, distribution, deletion, + archiving and application of keys in accordance with a security + policy." [I7498-2] + + $ Key Management Protocol (KMP) + (N) A protocol to establish a shared symmetric key between a pair + (or a group) of users. (One version of KMP was developed by SDNS, + and another by SILS.) Superseded by ISAKMP and IKE. + + $ key material + (D) Synonym for "keying material". + + Deprecated Usage: IDOCs SHOULD NOT use this term as a synonym for + "keying material". + + $ key pair + (I) A set of mathematically related keys -- a public key and a + private key -- that are used for asymmetric cryptography and are + generated in a way that makes it computationally infeasible to + derive the private key from knowledge of the public key. (See: + Diffie-Hellman-Merkle, RSA.) + + Tutorial: A key pair's owner discloses the public key to other + system entities so they can use the key to (a) encrypt data, (b) + verify a digital signature, or (c) generate a key with a key- + agreement algorithm. The matching private key is kept secret by + the owner, who uses it to (a') decrypt data, (b') generate a + digital signature, or (c') generate a key with a key-agreement + algorithm. + + $ key recovery + 1. (I) /cryptanalysis/ A process for learning the value of a + cryptographic key that was previously used to perform some + cryptographic operation. (See: cryptanalysis, recovery.) + + 2. (I) /backup/ Techniques that provide an intentional, alternate + means to access the key used for data confidentiality service in + an encrypted association. [DoD4] (Compare: recovery.) + + Tutorial: It is assumed that the cryptographic system includes a + primary means of obtaining the key through a key-establishment + algorithm or protocol. For the secondary means, there are two + classes of key recovery techniques: key encapsulation and key + escrow. + + + +Shirey Informational [Page 176] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ key space + (I) The range of possible values of a cryptographic key; or the + number of distinct transformations supported by a particular + cryptographic algorithm. (See: key length.) + + $ key translation center + (I) A type of key center that implements a key-distribution + protocol (based on symmetric cryptography) to convey keys between + two (or more) parties who wish to communicate securely. (Compare: + key distribution center.) + + Tutorial: A key translation center transfers keys for future + communication between Bob and Alice, who (a) wish to communicate + with each other but do not currently share keys, (b) each share a + KEK with the center, and (c) have the ability to generate or + acquire keys by themselves. Alice generates or acquires a set of + keys for communication with Bob. Alice encrypts the set in the KEK + she shares with the center and sends the encrypted set to the + center. The center decrypts the set, reencrypts the set in the KEK + it shares with Bob, and either (a) sends that reencrypted set to + Alice for her to forward to Bob or (b) sends it directly to Bob + (although direct distribution is not supported in the ANSI + standard [A9017]). + + $ key transport (algorithm or protocol) + 1. (I) A key establishment method by which a secret key is + generated by a system entity in a communication association and + securely sent to another entity in the association. (Compare: key + agreement.) + + Tutorial: Either (a) one entity generates a secret key and + securely sends it to the other entity, or (b) each entity + generates a secret value and securely sends it to the other + entity, where the two values are combined to form a secret key. + For example, a message originator can generate a random session + key and then use the RSA algorithm to encrypt that key with the + public key of the intended recipient. + + 2. (O) "The procedure to send a symmetric key from one party to + other parties. As a result, all legitimate participants share a + common symmetric key in such a way that the symmetric key is + determined entirely by one party." [A9042] + + $ key update + 1. (I) Derive a new key from an existing key. (Compare: rekey.) + + 2. (O) Irreversible cryptographic process that modifies a key to + produce a new key. [C4009] + + + +Shirey Informational [Page 177] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ key validation + 1. (I) "The procedure for the receiver of a public key to check + that the key conforms to the arithmetic requirements for such a + key in order to thwart certain types of attacks." [A9042] (See: + weak key) + + 2. (D) Synonym for "certificate validation". + + Deprecated Usage: IDOCs SHOULD NOT use the term as a synonym for + "certificate validation"; that would unnecessarily duplicate the + meaning of the latter term and mix concepts in a potentially + misleading way. In validating an X.509 public-key certificate, the + public key contained in the certificate is normally treated as an + opaque data object. + + $ keyed hash + (I) A cryptographic hash (e.g., [R1828]) in which the mapping to a + hash result is varied by a second input parameter that is a + cryptographic key. (See: checksum.) + + Tutorial: If the input data object is changed, a new, + corresponding hash result cannot be correctly computed without + knowledge of the secret key. Thus, the secret key protects the + hash result so it can be used as a checksum even when there is a + threat of an active attack on the data. There are two basic types + of keyed hash: + - A function based on a keyed encryption algorithm. Example: Data + Authentication Code. + - A function based on a keyless hash that is enhanced by + combining (e.g., by concatenating) the input data object + parameter with a key parameter before mapping to the hash + result. Example: HMAC. + + $ keying material + 1. (I) Data that is needed to establish and maintain a + cryptographic security association, such as keys, key pairs, and + IVs. + + 2. (O) "Key, code, or authentication information in physical or + magnetic form." [C4009] (Compare: COMSEC material.) + + $ keying material identifier (KMID) + 1. (I) An identifier assigned to an item of keying material. + + 2. (O) /MISSI/ A 64-bit identifier that is assigned to a key pair + when the public key is bound in a MISSI X.509 public-key + certificate. + + + + +Shirey Informational [Page 178] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ Khafre + (N) A patented, symmetric block cipher designed by Ralph C. Merkle + as a plug-in replacement for DES. [Schn] + + Tutorial: Khafre was designed for efficient encryption of small + amounts of data. However, because Khafre does not precompute + tables used for encryption, it is slower than Khufu for large + amounts of data. + + $ Khufu + (N) A patented, symmetric block cipher designed by Ralph C. Merkle + as a plug-in replacement for DES. [Schn] + + Tutorial: Khufu was designed for fast encryption of large amounts + of data. However, because Khufu precomputes tables used in + encryption, it is less efficient than Khafre for small amounts of + data. + + $ KLIF + (N) See: key loading and initialization facility. + + $ KMID + (I) See: keying material identifier. + + $ known-plaintext attack + (I) A cryptanalysis technique in which the analyst tries to + determine the key from knowledge of some plaintext-ciphertext + pairs (although the analyst may also have other clues, such as + knowing the cryptographic algorithm). + + $ kracker + (O) Old spelling for "cracker". + + $ KSOS, KSOS-6, KSOS-11 + (O) See: Kernelized Secure Operating System. + + $ L2F + (N) See: Layer 2 Forwarding Protocol. + + $ L2TP + (N) See: Layer 2 Tunneling Protocol. + + $ label + See: time stamp, security label. + + + + + + + +Shirey Informational [Page 179] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ laboratory attack + (O) "Use of sophisticated signal recovery equipment in a + laboratory environment to recover information from data storage + media." [C4009] + + $ LAN + (I) Abbreviation for "local area network" [R1983]. (See: [FP191].) + + $ land attack + (I) A denial-of-service attack that sends an IP packet that (a) + has the same address in both the Source Address and Destination + Address fields and (b) contains a TCP SYN packet that has the same + port number in both the Source Port and Destination Port fields. + + Derivation: This single-packet attack was named for "land", the + program originally published by the cracker who invented this + exploit. Perhaps that name was chosen because the inventor thought + of multi-packet (i.e., flooding) attacks as arriving by sea. + + $ Language of Temporal Ordering Specification (LOTOS) + (N) A language (ISO 8807-1990) for formal specification of + computer network protocols; describes the order in which events + occur. + + $ lattice + (I) A finite set together with a partial ordering on its elements + such that for every pair of elements there is a least upper bound + and a greatest lower bound. + + Example: A lattice is formed by a finite set S of security levels + -- i.e., a set S of all ordered pairs (x,c), where x is one of a + finite set X of hierarchically ordered classification levels X(1), + non-hierarchical categories C(1), ..., C(M) -- together with the + "dominate" relation. Security level (x,c) is said to "dominate" + (x',c') if and only if (a) x is greater (higher) than or equal to + x' and (b) c includes at least all of the elements of c'. (See: + dominate, lattice model.) + + Tutorial: Lattices are used in some branches of cryptography, both + as a basis for hard computational problems upon which + cryptographic algorithms can be defined, and also as a basis for + attacks on cryptographic algorithms. + + $ lattice model + 1. (I) A description of the semantic structure formed by a finite + set of security levels, such as those used in military + organizations. (See: dominate, lattice, security model.) + + + + +Shirey Informational [Page 180] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + 2. (I) /formal model/ A model for flow control in a system, based + on the lattice that is formed by the finite security levels in a + system and their partial ordering. [Denn] + + $ Law Enforcement Access Field (LEAF) + (N) A data item that is automatically embedded in data encrypted + by devices (e.g., CLIPPER chip) that implement the Escrowed + Encryption Standard. + + $ Layer 1, 2, 3, 4, 5, 6, 7 + (N) See: OSIRM. + + $ Layer 2 Forwarding Protocol (L2F) + (N) An Internet protocol (originally developed by Cisco + Corporation) that uses tunneling of PPP over IP to create a + virtual extension of a dial-up link across a network, initiated by + the dial-up server and transparent to the dial-up user. (See: + L2TP.) + + $ Layer 2 Tunneling Protocol (L2TP) + (N) An Internet client-server protocol that combines aspects of + PPTP and L2F and supports tunneling of PPP over an IP network or + over frame relay or other switched network. (See: VPN.) + + Tutorial: PPP can in turn encapsulate any OSIRM Layer 3 protocol. + Thus, L2TP does not specify security services; it depends on + protocols layered above and below it to provide any needed + security. + + $ LDAP + (I) See: Lightweight Directory Access Protocol. + + $ least common mechanism + (I) The principle that a security architecture should minimize + reliance on mechanisms that are shared by many users. + + Tutorial: Shared mechanisms may include cross-talk paths that + permit a breach of data security, and it is difficult to make a + single mechanism operate in a correct and trusted manner to the + satisfaction of a wide range of users. + + $ least privilege + (I) The principle that a security architecture should be designed + so that each system entity is granted the minimum system resources + and authorizations that the entity needs to do its work. (Compare: + economy of mechanism, least trust.) + + + + + +Shirey Informational [Page 181] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Tutorial: This principle tends to limit damage that can be caused + by an accident, error, or unauthorized act. This principle also + tends to reduce complexity and promote modularity, which can make + certification easier and more effective. This principle is similar + to the principle of protocol layering, wherein each layer provides + specific, limited communication services, and the functions in one + layer are independent of those in other layers. + + $ least trust + (I) The principle that a security architecture should be designed + in a way that minimizes (a) the number of components that require + trust and (b) the extent to which each component is trusted. + (Compare: least privilege, trust level.) + + $ legacy system + (I) A system that is in operation but will not be improved or + expanded while a new system is being developed to supersede it. + + $ legal non-repudiation + (I) See: secondary definition under "non-repudiation". + + $ leap of faith + 1. (I) /general security/ Operating a system as though it began + operation in a secure state, even though it cannot be proven that + such a state was established (i.e., even though a security + compromise might have occurred at or before the time when + operation began). + + 2. (I) /COMSEC/ The initial part, i.e., the first communication + step, or steps, of a protocol that is vulnerable to attack + (especially a man-in-the-middle attack) during that part but, if + that part is completed without being attacked, is subsequently not + vulnerable in later steps (i.e., results in a secure communication + association for which no man-in-the-middle attack is possible). + + Usage: This term is listed in English dictionaries, but their + definitions are broad and can be interpreted in many ways in + Internet contexts. Similarly, the definition stated here can be + interpreted in several ways. Therefore, IDOCs that use this term + (especially IDOCs that are protocol specifications) SHOULD state a + more specific definition for it. + + Tutorial: In a protocol, a leap of faith typically consists of + accepting a claim of peer identity, data origin, or data integrity + without authenticating that claim. When a protocol includes such a + step, the protocol might also be designed so that if a man-in- + the-middle attack succeeds during the vulnerable first part, then + the attacker must remain in the middle for all subsequent + + + +Shirey Informational [Page 182] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + exchanges or else one of the legitimate parties will be able to + detect the attack. + + $ level of concern + (N) /U.S. DoD/ A rating assigned to an information system that + indicates the extent to which protective measures, techniques, and + procedures must be applied. (See: critical, sensitive, level of + robustness.) + + $ level of robustness + (N) /U.S. DoD/ A characterization of (a) the strength of a + security function, mechanism, service, or solution and (b) the + assurance (or confidence) that it is implemented and functioning. + [Cons, IATF] (See: level of concern.) + + $ Liberty Alliance + (O) An international consortium of more than 150 commercial, + nonprofit, and governmental organizations that was created in 2001 + to address technical, business, and policy problems of identity + and identity-based Web services and develop a standard for + federated network identity that supports current and emerging + network devices. + + $ Lightweight Directory Access Protocol (LDAP) + (I) An Internet client-server protocol (RFC 3377) that supports + basic use of the X.500 Directory (or other directory servers) + without incurring the resource requirements of the full Directory + Access Protocol (DAP). + + Tutorial: Designed for simple management and browser applications + that provide simple read/write interactive directory service. + Supports both simple authentication and strong authentication of + the client to the directory server. + + $ link + 1a. (I) A communication facility or physical medium that can + sustain data communications between multiple network nodes, in the + protocol layer immediately below IP. (RFC 3753) + + 1b. (I) /subnetwork/ A communication channel connecting subnetwork + relays (especially one between two packet switches) that is + implemented at OSIRM Layer 2. (See: link encryption.) + + Tutorial: The relay computers assume that links are logically + passive. If a computer at one end of a link sends a sequence of + bits, the sequence simply arrives at the other end after a finite + time, although some bits may have been changed either accidentally + (errors) or by active wiretapping. + + + +Shirey Informational [Page 183] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + 2. (I) /World Wide Web/ See: hyperlink. + + $ link encryption + (I) Stepwise (link-by-link) protection of data that flows between + two points in a network, provided by encrypting data separately on + each network link, i.e., by encrypting data when it leaves a host + or subnetwork relay and decrypting when it arrives at the next + host or relay. Each link may use a different key or even a + different algorithm. [R1455] (Compare: end-to-end encryption.) + + $ liveness + (I) A property of a communication association or a feature of a + communication protocol that provides assurance to the recipient of + data that the data is being freshly transmitted by its originator, + i.e., that the data is not being replayed, by either the + originator or a third party, from a previous transmission. (See: + fresh, nonce, replay attack.) + + $ logic bomb + (I) Malicious logic that activates when specified conditions are + met. Usually intended to cause denial of service or otherwise + damage system resources. (See: Trojan horse, virus, worm.) + + $ login + 1a. (I) An act by which a system entity establishes a session in + which the entity can use system resources. (See: principal, + session.) + + 1b. (I) An act by which a system user has its identity + authenticated by the system. (See: principal, session.) + + Usage: Usually understood to be accomplished by providing an + identifier and matching authentication information (e.g., a + password) to a security mechanism that authenticates the user's + identity; but sometimes refers to establishing a connection with a + server when no authentication or specific authorization is + involved. + + Derivation: Refers to "log" file, a security audit trail that + records (a) security events, such as the beginning of a session, + and (b) the names of the system entities that initiate events. + + $ long title + (O) /U.S. Government/ "Descriptive title of [an item of COMSEC + material]." [C4009] (Compare: short title.) + + + + + + +Shirey Informational [Page 184] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ low probability of detection + (I) Result of TRANSEC measures used to hide or disguise a + communication. + + $ low probability of intercept + (I) Result of TRANSEC measures used to prevent interception of a + communication. + + $ LOTOS + (N) See: Language of Temporal Ordering Specification. + + $ MAC + (N) See: mandatory access control, Message Authentication Code. + + Deprecated Usage: IDOCs that use this term SHOULD state a + definition for it because this abbreviation is ambiguous. + + $ magnetic remanence + (N) Magnetic representation of residual information remaining on a + magnetic medium after the medium has been cleared. [NCS25] (See: + clear, degauss, purge.) + + $ main mode + (I) See: /IKE/ under "mode". + + $ maintenance hook + (N) "Special instructions (trapdoors) in software allowing easy + maintenance and additional feature development. Since maintenance + hooks frequently allow entry into the code without the usual + checks, they are a serious security risk if they are not removed + prior to live implementation." [C4009] (See: back door.) + + $ malicious logic + (I) Hardware, firmware, or software that is intentionally included + or inserted in a system for a harmful purpose. (See: logic bomb, + Trojan horse, spyware, virus, worm. Compare: secondary definitions + under "corruption", "incapacitation", "masquerade", and "misuse".) + + $ malware + (D) A contraction of "malicious software". (See: malicious logic.) + + Deprecated Term: IDOCs SHOULD NOT use this term; it is not listed + in most dictionaries and could confuse international readers. + + $ MAN + (I) metropolitan area network. + + + + + +Shirey Informational [Page 185] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ man-in-the-middle attack + (I) A form of active wiretapping attack in which the attacker + intercepts and selectively modifies communicated data to + masquerade as one or more of the entities involved in a + communication association. (See: hijack attack, piggyback attack.) + + Tutorial: For example, suppose Alice and Bob try to establish a + session key by using the Diffie-Hellman-Merkle algorithm without + data origin authentication service. A "man in the middle" could + (a) block direct communication between Alice and Bob and then (b) + masquerade as Alice sending data to Bob, (c) masquerade as Bob + sending data to Alice, (d) establish separate session keys with + each of them, and (e) function as a clandestine proxy server + between them to capture or modify sensitive information that Alice + and Bob think they are sending only to each other. + + $ manager + (I) A person who controls the service configuration of a system or + the functional privileges of operators and other users. (See: + administrative security. Compare: operator, SSO, user.) + + $ mandatory access control + 1. (I) An access control service that enforces a security policy + based on comparing (a) security labels, which indicate how + sensitive or critical system resources are, with (b) security + clearances, which indicate that system entities are eligible to + access certain resources. (See: discretionary access control, MAC, + rule-based security policy.) + + Derivation: This kind of access control is called "mandatory" + because an entity that has clearance to access a resource is not + permitted, just by its own volition, to enable another entity to + access that resource. + + 2. (O) "A means of restricting access to objects based on the + sensitivity (as represented by a label) of the information + contained in the objects and the formal authorization (i.e., + clearance) of subjects to access information of such sensitivity." + [DoD1] + + $ manipulation detection code + (D) Synonym for "checksum". + + Deprecated Term: IDOCs SHOULD NOT use this term as a synonym for + "checksum"; the word "manipulation" implies protection against + active attacks, which an ordinary checksum might not provide. + Instead, if such protection is intended, use "protected checksum" + or some particular type thereof, depending on which is meant. If + + + +Shirey Informational [Page 186] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + such protection is not intended, use "error detection code" or + some specific type of checksum that is not protected. + + $ marking + See: time stamp, security marking. + + $ MARS + (O) A symmetric, 128-bit block cipher with variable key length + (128 to 448 bits), developed by IBM as a candidate for the AES. + + $ Martian + (D) /slang/ A packet that arrives unexpectedly at the wrong + address or on the wrong network because of incorrect routing or + because it has a non-registered or ill-formed IP address. [R1208] + + Deprecated Term: It is likely that other cultures use different + metaphors for this concept. Therefore, to avoid international + misunderstanding, IDOCs SHOULD NOT use this term. (See: Deprecated + Usage under "Green Book".) + + $ masquerade + (I) A type of threat action whereby an unauthorized entity gains + access to a system or performs a malicious act by illegitimately + posing as an authorized entity. (See: deception.) + + Usage: This type of threat action includes the following subtypes: + - "Spoof": Attempt by an unauthorized entity to gain access to a + system by posing as an authorized user. + - "Malicious logic": In context of masquerade, any hardware, + firmware, or software (e.g., Trojan horse) that appears to + perform a useful or desirable function, but actually gains + unauthorized access to system resources or tricks a user into + executing other malicious logic. (See: corruption, + incapacitation, main entry for "malicious logic", misuse.) + + $ MCA + (O) See: merchant certification authority. + + $ MD2 + (N) A cryptographic hash [R1319] that produces a 128-bit hash + result, was designed by Ron Rivest, and is similar to MD4 and MD5 + but slower. + + Derivation: Apparently, an abbreviation of "message digest", but + that term is deprecated by this Glossary. + + + + + + +Shirey Informational [Page 187] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ MD4 + (N) A cryptographic hash [R1320] that produces a 128-bit hash + result and was designed by Ron Rivest. (See: Derivation under + "MD2", SHA-1.) + + $ MD5 + (N) A cryptographic hash [R1321] that produces a 128-bit hash + result and was designed by Ron Rivest to be an improved version of + MD4. (See: Derivation under "MD2".) + + $ merchant + (O) /SET/ "A seller of goods, services, and/or other information + who accepts payment for these items electronically." [SET2] A + merchant may also provide electronic selling services and/or + electronic delivery of items for sale. With SET, the merchant can + offer its cardholders secure electronic interactions, but a + merchant that accepts payment cards is required to have a + relationship with an acquirer. [SET1, SET2] + + $ merchant certificate + (O) /SET/ A public-key certificate issued to a merchant. Sometimes + used to refer to a pair of such certificates where one is for + digital signature use and the other is for encryption. + + $ merchant certification authority (MCA) + (O) /SET/ A CA that issues digital certificates to merchants and + is operated on behalf of a payment card brand, an acquirer, or + another party according to brand rules. Acquirers verify and + approve requests for merchant certificates prior to issuance by + the MCA. An MCA does not issue a CRL, but does distribute CRLs + issued by root CAs, brand CAs, geopolitical CAs, and payment + gateway CAs. [SET2] + + $ mesh PKI + (I) A non-hierarchical PKI architecture in which there are several + trusted CAs rather than a single root. Each certificate user bases + path validations on the public key of one of the trusted CAs, + usually the one that issued that user's own public-key + certificate. Rather than having superior-to-subordinate + relationships between CAs, the relationships are peer-to-peer, and + CAs issue cross-certificates to each other. (Compare: hierarchical + PKI, trust-file PKI.) + + $ Message Authentication Code (MAC), message authentication code + 1. (N) /capitalized/ A specific ANSI standard for a checksum that + is computed with a keyed hash that is based on DES. [A9009] Usage: + a.k.a. Data Authentication Code, which is a U.S. Government + standard. [FP113] (See: MAC.) + + + +Shirey Informational [Page 188] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + 2. (D) /not capitalized/ Synonym for "error detection code". + + Deprecated Term: IDOCs SHOULD NOT use the uncapitalized form + "message authentication code". Instead, use "checksum", "error + detection code", "hash", "keyed hash", "Message Authentication + Code", or "protected checksum", depending on what is meant. (See: + authentication code.) + + The uncapitalized form mixes concepts in a potentially misleading + way. The word "message" is misleading because it implies that the + mechanism is particularly suitable for or limited to electronic + mail (see: Message Handling Systems). The word "authentication" is + misleading because the mechanism primarily serves a data integrity + function rather than an authentication function. The word "code" + is misleading because it implies that either encoding or + encryption is involved or that the term refers to computer + software. + + $ message digest + (D) Synonym for "hash result". (See: cryptographic hash.) + + Deprecated Term: IDOCs SHOULD NOT use this term as a synonym for + "hash result"; this term unnecessarily duplicates the meaning of + the other, more general term and mixes concepts in a potentially + misleading way. The word "message" is misleading because it + implies that the mechanism is particularly suitable for or limited + to electronic mail (see: Message Handling Systems). + + $ message handling system + (D) Synonym for the Internet electronic mail system. + + Deprecated Term: IDOCs SHOULD NOT use this term, because it could + be confused with Message Handling System. Instead, use "Internet + electronic mail" or some other, more specific term. + + $ Message Handling System + (O) An ITU-T system concept that encompasses the notion of + electronic mail but defines more comprehensive OSI systems and + services that enable users to exchange messages on a store-and- + forward basis. (The ISO equivalent is "Message Oriented Text + Interchange System".) (See: X.400.) + + $ message indicator + 1. (D) /cryptographic function/ Synonym for "initialization + value". (Compare: indicator.) + + 2. (D) "Sequence of bits transmitted over a communications system + for synchronizing cryptographic equipment." [C4009] + + + +Shirey Informational [Page 189] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Deprecated Term: IDOCs SHOULD NOT use this term as a synonym for + "initialization value"; the term mixes concepts in a potentially + misleading way. The word "message" is misleading because it + suggests that the mechanism is specific to electronic mail. (See: + Message Handling System.) + + $ message integrity check + $ message integrity code (MIC) + (D) Synonyms for some form of "checksum". + + Deprecated Term: IDOCs SHOULD NOT use these terms for any form of + checksum. Instead, use "checksum", "error detection code", "hash", + "keyed hash", "Message Authentication Code", or "protected + checksum", depending on what is meant. + + These two terms mix concepts in potentially misleading ways. The + word "message" is misleading because it suggests that the + mechanism is particularly suitable for or limited to electronic + mail. The word "integrity" is misleading because the checksum may + be used to perform a data origin authentication function rather + than an integrity function. The word "code" is misleading because + it suggests either that encoding or encryption is involved or that + the term refers to computer software. + + $ Message Security Protocol (MSP) + (N) A secure message handling protocol [SDNS7] for use with X.400 + and Internet mail protocols. Developed by NSA's SDNS program and + used in the U.S. DoD's Defense Message System. + + $ meta-data + (I) Descriptive information about a data object; i.e., data about + data, or data labels that describe other data. (See: security + label. Compare: metadata) + + Tutorial: Meta-data can serve various management purposes: + - System management: File name, type, size, creation date. + - Application management: Document title, version, author. + - Usage management: Data categories, keywords, classifications. + + Meta-data can be associated with a data object in two basic ways: + - Explicitly: Be part of the data object (e.g., a header field of + a data file or packet) or be linked to the object. + - Implicitly: Be associated with the data object because of some + other, explicit attribute of the object. + + $ metadata, Metadata(trademark), METADATA(trademark) + (D) Proprietary variants of "meta-data". (See: SPAM(trademark).) + + + + +Shirey Informational [Page 190] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Deprecated Usage: IDOCs SHOULD NOT use these unhypenated forms; + IDOCs SHOULD use only the uncapitalized, hyphenated "meta-data". + The terms "Metadata" and "METADATA" are claimed as registered + trademarks (numbers 1,409,260 and 2,185,504) owned by The Metadata + Company, originally known as Metadata Information Partners, a + company founded by Jack Myers. The status of "metadata" is + unclear. + + $ MHS + (N) See: message handling system. + + $ MIC + (D) See: message integrity code. + + $ MIME + (I) See: Multipurpose Internet Mail Extensions. + + $ MIME Object Security Services (MOSS) + (I) An Internet protocol [R1848] that applies end-to-end + encryption and digital signature to MIME message content, using + symmetric cryptography for encryption and asymmetric cryptography + for key distribution and signature. MOSS is based on features and + specifications of PEM. (See: S/MIME.) + + $ Minimum Interoperability Specification for PKI Components (MISPC) + (N) A technical description to provide a basis for interoperation + between PKI components from different vendors; consists primarily + of a profile of certificate and CRL extensions and a set of + transactions for PKI operation. [SP15] + + $ misappropriation + (I) A type of threat action whereby an entity assumes unauthorized + logical or physical control of a system resource. (See: + usurpation.) + + Usage: This type of threat action includes the following subtypes: + - Theft of data: Unauthorized acquisition and use of data + contained in a system. + - Theft of service: Unauthorized use of a system service. + - Theft of functionality: Unauthorized acquisition of actual + hardware, firmware, or software of a system component. + + $ MISPC + (N) See: Minimum Interoperability Specification for PKI + Components. + + + + + + +Shirey Informational [Page 191] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ MISSI + (O) Multilevel Information System Security Initiative, an NSA + program to encourage development of interoperable, modular + products for constructing secure network information systems in + support of a wide variety of U.S. Government missions. (See: MSP, + SP3, SP4.) + + $ MISSI user + (O) /MISSI/ A system entity that is the subject of one or more + MISSI X.509 public-key certificates issued under a MISSI + certification hierarchy. (See: personality.) + + Tutorial: MISSI users include both end users and the authorities + that issue certificates. A MISSI user is usually a person but may + be a machine or other automated process. Machines that are + required to operate nonstop may be issued their own certificates + to avoid downtime needed to exchange the FORTEZZA cards of machine + operators at shift changes. + + $ mission + (I) A statement of a (relatively long-term) duty or (relatively + short-term) task that is assigned to an organization or system, + indicates the purpose and objectives of the duty or task, and may + indicate the actions to be taken to achieve it. + + $ mission critical + (I) A condition of a system service or other system resource such + that denial of access to, or lack of availability of, the resource + would jeopardize a system user's ability to perform a primary + mission function or would result in other serious consequences. + (See: Critical. Compare: mission essential.) + + $ mission essential + (O) /U.S. DoD/ Refers to materiel that is authorized and available + to combat, combat support, combat service support, and combat + readiness training forces to accomplish their assigned missions. + [JP1] (Compare: mission critical.) + + $ misuse + 1. (I) The intentional use (by authorized users) of system + resources for other than authorized purposes. Example: An + authorized system administrator creates an unauthorized account + for a friend. (See: misuse detection.) + + 2. (I) A type of threat action that causes a system component to + perform a function or service that is detrimental to system + security. (See: usurpation.) + + + + +Shirey Informational [Page 192] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Usage: This type of threat action includes the following subtypes: + - "Tampering": /misuse/ Deliberately altering a system's logic, + data, or control information to cause the system to perform + unauthorized functions or services. (See: corruption, main + entry for "tampering".) + - "Malicious logic": /misuse/ Any hardware, firmware, or software + intentionally introduced into a system to perform or control + execution of an unauthorized function or service. (See: + corruption, incapacitation, main entry for "malicious logic", + masquerade.) + - "Violation of authorizations": Action by an entity that exceeds + the entity's system privileges by executing an unauthorized + function. (See: authorization.) + + $ misuse detection + (I) An intrusion detection method that is based on rules that + specify system events, sequences of events, or observable + properties of a system that are believed to be symptomatic of + security incidents. (See: IDS, misuse. Compare: anomaly + detection.) + + $ MLS + (I) See: multilevel secure + + $ mobile code + 1a. (I) Software that originates from a remote server, is + transmitted across a network, and is loaded onto and executed on a + local client system without explicit initiation by the client's + user and, in some cases, without that user's knowledge. (Compare: + active content.) + + Tutorial: One form of mobile code is active content in a file that + is transferred across a network. + + 1b. (O) /U.S. DoD/ "Software modules obtained from remote systems, + transferred across a network, and then downloaded and executed on + local systems without explicit installation or execution by the + recipient." [JP1] + + 2a. (O) /U.S. DoD/ Technology that enables the creation of + executable information that can be delivered to an information + system and directly executed on any hardware/software architecture + that has an appropriate host execution environment. + + 2b. (O) "Programs (e.g., script, macro, or other portable + instruction) that can be shipped unchanged to a heterogeneous + collection of platforms and executed with identical semantics" + [SP28]. (See: active content.) + + + +Shirey Informational [Page 193] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Tutorial: Mobile code might be malicious. Using techniques such as + "code signing" and a "sandbox" can reduce the risks of receiving + and executing mobile code. + + $ mode + $ mode of operation + 1. (I) /cryptographic operation/ A technique for enhancing the + effect of a cryptographic algorithm or adapting the algorithm for + an application, such as applying a block cipher to a sequence of + data blocks or a data stream. (See: CBC, CCM, CMAC, CFB, CTR, ECB, + OFB.) + + 2. (I) /system operation/ A type of security policy that states + the range of classification levels of information that a system is + permitted to handle and the range of clearances and authorizations + of users who are permitted to access the system. (See: + compartmented security mode, controlled security mode, dedicated + security mode, multilevel security mode, partitioned security + mode, system-high security mode. Compare: protection level.) + + 3. (I) /IKE/ IKE refers to its various types of ISAKMP-scripted + exchanges of messages as "modes". Among these are the following: + - "Main mode": One of IKE's two phase 1 modes. (See: ISAKMP.) + - "Quick mode": IKE's only phase 2 mode. (See: ISAKMP.) + + $ model + See: formal model, security model. + + $ modulus + (I) The defining constant in modular arithmetic, and usually a + part of the public key in asymmetric cryptography that is based on + modular arithmetic. (See: Diffie-Hellman-Merkle, RSA.) + + $ Mondex + (O) A smartcard-based electronic money system that incorporates + cryptography and can be used to make payments via the Internet. + (See: IOTP.) + + $ Morris Worm + (I) A worm program that flooded the ARPANET in November 1988, + causing problems for thousands of hosts. [R1135] (See: community + risk, worm) + + $ MOSS + (I) See: MIME Object Security Services. + + + + + + +Shirey Informational [Page 194] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ MQV + (N) A key-agreement protocol [Mene] that was proposed by A.J. + Menezes, M. Qu, and S.A. Vanstone in 1995 and is based on the + Diffie-Hellman-Merkle algorithm. + + $ MSP + (N) See: Message Security Protocol. + + $ multicast security + See: secure multicast + + $ Multics + (N) MULTiplexed Information and Computing Service, an MLS computer + timesharing system designed and implemented during 1965-69 by a + consortium including Massachusetts Institute of Technology, + General Electric, and Bell Laboratories, and later offered + commercially by Honeywell. + + Tutorial: Multics was one of the first large, general-purpose, + operating systems to include security as a primary goal from the + inception of the design and development and was rated in TCSEC + Class B2. Its many innovative hardware and software security + mechanisms (e.g., protection ring) were adopted by later systems. + + $ multilevel secure (MLS) + (I) Describes an information system that is trusted to contain, + and maintain separation between, resources (particularly stored + data) of different security levels. (Examples: BLACKER, CANEWARE, + KSOS, Multics, SCOMP.) + + Usage: Usually understood to mean that the system permits + concurrent access by users who differ in their access + authorizations, while denying users access to resources for which + they lack authorization. + + $ multilevel security mode + 1. (N) A mode of system operation wherein (a) two or more security + levels of information are allowed to be to be handled concurrently + within the same system when some users having access to the system + have neither a security clearance nor need-to-know for some of the + data handled by the system and (b) separation of the users and the + classified material on the basis, respectively, of clearance and + classification level are dependent on operating system control. + (See: /system operation/ under "mode", need to know, protection + level, security clearance. Compare: controlled mode.) + + + + + + +Shirey Informational [Page 195] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Usage: Usually abbreviated as "multilevel mode". This term was + defined in U.S. Government policy regarding system accreditation, + but the term is also used outside the Government. + + 2. (O) A mode of system operation in which all three of the + following statements are true: (a) Some authorized users do not + have a security clearance for all the information handled in the + system. (b) All authorized users have the proper security + clearance and appropriate specific access approval for the + information to which they have access. (c) All authorized users + have a need-to-know only for information to which they have + access. [C4009] (See: formal access approval, protection level.) + + $ Multipurpose Internet Mail Extensions (MIME) + (I) An Internet protocol (RFC 2045) that enhances the basic format + of Internet electronic mail messages (RFC 822) (a) to enable + character sets other than U.S. ASCII to be used for textual + headers and content and (b) to carry non-textual and multi-part + content. (See: S/MIME.) + + $ mutual suspicion + (I) The state that exists between two interacting system entities + in which neither entity can trust the other to function correctly + with regard to some security requirement. + + $ name + (I) Synonym for "identifier". + + $ naming authority + (O) /U.S. DoD/ An organizational entity responsible for assigning + DNs and for assuring that each DN is meaningful and unique within + its domain. [DoD9] + + $ National Computer Security Center (NCSC) + (O) A U.S. DoD organization, housed in NSA, that has + responsibility for encouraging widespread availability of trusted + systems throughout the U.S. Federal Government. It has established + criteria for, and performed evaluations of, computer and network + systems that have a TCB. (See: Rainbow Series, TCSEC.) + + $ National Information Assurance Partnership (NIAP) + (N) A joint initiative of NIST and NSA to enhance the quality of + commercial products for information security and increase consumer + confidence in those products through objective evaluation and + testing methods. + + + + + + +Shirey Informational [Page 196] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Tutorial: NIAP is registered, through the U.S. DoD, as a National + Performance Review Reinvention Laboratory. NIAP functions include + the following: + - Developing tests, test methods, and other tools that developers + and testing laboratories may use to improve and evaluate + security products. + - Collaborating with industry and others on research and testing + programs. + - Using the Common Criteria to develop protection profiles and + associated test sets for security products and systems. + - Cooperating with the NIST National Voluntary Laboratory + Accreditation Program to develop a program to accredit private- + sector laboratories for the testing of information security + products using the Common Criteria. + - Working to establish a formal, international mutual recognition + scheme for a Common Criteria-based evaluation. + + $ National Institute of Standards and Technology (NIST) + (N) A U.S. Department of Commerce organization that promotes U.S. + economic growth by working with industry to develop and apply + technology, measurements, and standards. Has primary U.S. + Government responsibility for INFOSEC standards for sensitive + unclassified information. (See: ANSI, DES, DSA, DSS, FIPS, NIAP, + NSA.) + + $ National Reliability and Interoperability Council (NRIC) + (N) An advisory committee chartered by the U.S. Federal + Communications Commission (FCC), with participation by network + service providers and vendors, to provide recommendations to the + FCC for assuring reliability, interoperability, robustness, and + security of wireless, wireline, satellite, cable, and public data + communication networks. + + $ national security + (O) /U.S. Government/ The national defense or foreign relations of + the United States of America. + + $ National Security Agency (NSA) + (N) A U.S. DoD organization that has primary U.S. Government + responsibility for INFOSEC standards for classified information + and for sensitive unclassified information handled by national + security systems. (See: FORTEZZA, KEA, MISSI, national security + system, NIAP, NIST, SKIPJACK.) + + $ national security information + (O) /U.S. Government/ Information that has been determined, + pursuant to Executive Order 12958 or any predecessor order, to + require protection against unauthorized disclosure. [C4009] + + + +Shirey Informational [Page 197] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ national security system + (O) /U.S. Government/ Any Government-operated information system + for which the function, operation, or use (a) involves + intelligence activities; (b) involves cryptologic activities + related to national security; (c) involves command and control of + military forces; (d) involves equipment that is an integral part + of a weapon or weapon system; or (e) is critical to the direct + fulfillment of military or intelligence missions and does not + include a system that is to be used for routine administrative and + business applications (including payroll, finance, logistics, and + personnel management applications). [Title 40 U.S.C. Section 1552, + Information Technology Management Reform Act of 1996.] (See: type + 2 product.) + + $ natural disaster + (I) /threat action/ See: secondary definitions under "corruption" + and "incapacitation". + + $ NCSC + (O) See: National Computer Security Center. + + $ need to know, need-to-know + (I) The necessity for access to, knowledge of, or possession of + specific information required to carry out official duties. + + Usage: The compound "need-to-know" is commonly used as either an + adjective or a noun. + + Tutorial: The need-to-know criterion is used in security + procedures that require a custodian of sensitive information, + prior to disclosing the information to someone else, to establish + that the intended recipient has proper authorization to access the + information. + + $ network + (I) An information system comprised of a collection of + interconnected nodes. (See: computer network.) + + $ Network Hardware Layer + (I) See: Internet Protocol Suite. + + $ Network Interface Layer + (I) See: Internet Protocol Suite. + + $ Network Layer Security Protocol (NLSP). + (N) An OSI protocol (IS0 11577) for end-to-end encryption services + at the top of OSIRM Layer 3. NLSP is derived from SP3 but is more + complex. (Compare: IPsec.) + + + +Shirey Informational [Page 198] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ Network Substrate Layer + (I) Synonym for "Network Hardware Layer". + + $ network weaving + (I) A penetration technique in which an intruder avoids detection + and traceback by using multiple, linked, communication networks to + access and attack a system. [C4009] + + $ NIAP + (N) See: National Information Assurance Partnership. + + $ nibble + (D) Half of a byte (i.e., usually, 4 bits). + + Deprecated Term: To avoid international misunderstanding, IDOCs + SHOULD NOT use this term; instead, state the size of the block + explicitly (e.g., "4-bit block"). (See: Deprecated Usage under + "Green Book".) + + $ NIPRNET + (O) The U.S. DoD's common-use Non-Classified Internet Protocol + Router Network; the part of the Internet that is wholly controlled + by the U.S. DoD and is used for official DoD business. + + $ NIST + (N) See: National Institute of Standards and Technology. + + $ NLSP + (N) See: Network Layer Security Protocol + + $ no-lone zone + (I) A room or other space or area to which no person may have + unaccompanied access and that, when occupied, is required to be + occupied by two or more appropriately authorized persons. [C4009] + (See: dual control.) + + $ no-PIN ORA (NORA) + (O) /MISSI/ An organizational RA that operates in a mode in which + the ORA performs no card management functions and, therefore, does + not require knowledge of either the SSO PIN or user PIN for an end + user's FORTEZZA PC card. + + $ node + (I) A collection of related subsystems located on one or more + computer platforms at a single site. (See: site.) + + + + + + +Shirey Informational [Page 199] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ nonce + (I) A random or non-repeating value that is included in data + exchanged by a protocol, usually for the purpose of guaranteeing + liveness and thus detecting and protecting against replay attacks. + (See: fresh.) + + $ non-critical + See: critical. + + $ non-repudiation service + 1. (I) A security service that provide protection against false + denial of involvement in an association (especially a + communication association that transfers data). (See: repudiation, + time stamp.) + + Tutorial: Two separate types of denial are possible -- an entity + can deny that it sent a data object, or it can deny that it + received a data object -- and, therefore, two separate types of + non-repudiation service are possible. (See: non-repudiation with + proof of origin, non-repudiation with proof of receipt.) + + 2. (D) "Assurance [that] the sender of data is provided with proof + of delivery and the recipient is provided with proof of the + sender's identity, so neither can later deny having processed the + data." [C4009] + + Deprecated Definition: IDOCs SHOULD NOT use definition 2 because + it bundles two security services -- non-repudiation with proof of + origin, and non-repudiation with proof of receipt -- that can be + provided independently of each other. + + Usage: IDOCs SHOULD distinguish between the technical aspects and + the legal aspects of a non-repudiation service: + - "Technical non-repudiation": Refers to the assurance a relying + party has that if a public key is used to validate a digital + signature, then that signature had to have been made by the + corresponding private signature key. [SP32] + - "Legal non-repudiation": Refers to how well possession or + control of the private signature key can be established. [SP32] + + Tutorial: Non-repudiation service does not prevent an entity from + repudiating a communication. Instead, the service provides + evidence that can be stored and later presented to a third party + to resolve disputes that arise if and when a communication is + repudiated by one of the entities involved. + + + + + + +Shirey Informational [Page 200] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Ford describes the six phases of a complete non-repudiation + service and uses "critical action" to refer to the act of + communication that is the subject of the service [For94, For97]: + + -------- -------- -------- -------- -------- . -------- + Phase 1: Phase 2: Phase 3: Phase 4: Phase 5: . Phase 6: + Request Generate Transfer Verify Retain . Resolve + Service Evidence Evidence Evidence Evidence . Dispute + -------- -------- -------- -------- -------- . -------- + + Service Critical Evidence Evidence Archive . Evidence + Request => Action => Stored => Is => Evidence . Is + Is Made Occurs For Later Tested In Case . Verified + and Use | ^ Critical . ^ + Evidence v | Action Is . | + Is +-------------------+ Repudiated . | + Generated |Verifiable Evidence|------> ... . ----+ + +-------------------+ + + Phase / Explanation + ------------------- + 1. Request service: Before the critical action, the service + requester asks, either implicitly or explicitly, to have + evidence of the action be generated. + 2. Generate evidence: When the critical action occurs, evidence is + generated by a process involving the potential repudiator and + possibly also a trusted third party. + 3. Transfer evidence: The evidence is transferred to the requester + or stored by a third party, for later use (if needed). + 4. Verify evidence: The entity that holds the evidence tests it to + be sure that it will suffice if a dispute arises. + 5. Retain evidence: The evidence is retained for possible future + retrieval and use. + 6. Resolve dispute: In this phase, which occurs only if the + critical action is repudiated, the evidence is retrieved from + storage, presented, and verified to resolve the dispute. + + $ non-repudiation with proof of origin + (I) A security service that provides the recipient of data with + evidence that proves the origin of the data, and thus protects the + recipient against an attempt by the originator to falsely deny + sending the data. (See: non-repudiation service.) + + Tutorial: This service is a strong version of data origin + authentication service. This service can not only verify the + identity of a system entity that is the original source of + received data; it can also provide proof of that identity to a + third party. + + + +Shirey Informational [Page 201] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ non-repudiation with proof of receipt + (I) A security service that provides the originator of data with + evidence that proves the data was received as addressed, and thus + protects the originator against an attempt by the recipient to + falsely deny receiving the data. (See: non-repudiation service.) + + $ non-volatile media + (I) Storage media that, once written into, provide stable storage + of information without an external power supply. (Compare: + permanent storage, volatile media.) + + $ NORA + (O) See: no-PIN ORA. + + $ notarization + (I) Registration of data under the authority or in the care of a + trusted third party, thus making it possible to provide subsequent + assurance of the accuracy of characteristics claimed for the data, + such as content, origin, time of existence, and delivery. + [I7498-2] (See: digital notary.) + + $ NRIC + (N) See: Network Reliability and Interoperability Council. + + $ NSA + (N) See: National Security Agency + + $ null + (N) /encryption/ "Dummy letter, letter symbol, or code group + inserted into an encrypted message to delay or prevent its + decryption or to complete encrypted groups for transmission or + transmission security purposes." [C4009] + + $ NULL encryption algorithm + (I) An algorithm [R2410] that is specified as doing nothing to + transform plaintext data; i.e., a no-op. It originated because ESP + always specifies the use of an encryption algorithm for + confidentiality. The NULL encryption algorithm is a convenient way + to represent the option of not applying encryption in ESP (or in + any other context where a no-op is needed). (Compare: null.) + + $ OAKLEY + (I) A key establishment protocol (proposed for IPsec but + superseded by IKE) based on the Diffie-Hellman-Merkle algorithm + and designed to be a compatible component of ISAKMP. [R2412] + + Tutorial: OAKLEY establishes a shared key with an assigned + identifier and associated authenticated identities for parties; + + + +Shirey Informational [Page 202] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + i.e., OAKLEY provides authentication service to ensure the + entities of each other's identity, even if the Diffie-Hellman- + Merkle exchange is threatened by active wiretapping. Also, it + provides public-key forward secrecy for the shared key and + supports key updates, incorporation of keys distributed by out-of- + band mechanisms, and user-defined abstract group structures for + use with Diffie-Hellman-Merkle. + + $ object + (I) /formal model/ Trusted-system modeling usage: A system + component that contains or receives information. (See: Bell- + LaPadula model, object reuse, trusted system.) + + $ object identifier (OID) + 1. (N) An official, globally unique name for a thing, written as a + sequence of integers (which are formed and assigned as defined in + the ASN.1 standard) and used to reference the thing in abstract + specifications and during negotiation of security services in a + protocol. + + 2. (O) "A value (distinguishable from all other such values) + [that] is associated with an object." [X680] + + Tutorial: Objects named by OIDs are leaves of the object + identifier tree (which is similar to but different from the X.500 + Directory Information Tree). Each arc (i.e., each branch of the + tree) is labeled with a non-negative integer. An OID is the + sequence of integers on the path leading from the root of the tree + to a named object. + + The OID tree has three arcs immediately below the root: {0} for + use by ITU-T, {1} for use by ISO, and {2} for use by both jointly. + Below ITU-T are four arcs, where {0 0} is for ITU-T + recommendations. Below {0 0} are 26 arcs, one for each series of + recommendations starting with the letters A to Z, and below these + are arcs for each recommendation. Thus, the OID for ITU-T + Recommendation X.509 is {0 0 24 509}. Below ISO are four arcs, + where {1 0 }is for ISO standards, and below these are arcs for + each ISO standard. Thus, the OID for ISO/IEC 9594-8 (the ISO + number for X.509) is {1 0 9594 8}. + + ANSI registers organization names below the branch {joint-iso- + ccitt(2) country(16) US(840) organization(1) gov(101) csor(3)}. + The NIST CSOR records PKI objects below the branch {joint-iso-itu- + t(2) country(16) us(840) organization (1) gov(101) csor(3)}. The + U.S. DoD registers INFOSEC objects below the branch {joint-iso- + itu-t(2) country(16) us(840) organization(1) gov(101) dod(2) + infosec(1)}. + + + +Shirey Informational [Page 203] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + The IETF's Public-Key Infrastructure (pkix) Working Group + registers PKI objects below the branch {iso(1) identified- + organization(3) dod(6) internet(1) security(5) mechanisms(5) + pkix(7)}. [R3280] + + $ object reuse + (N) /COMPUSEC/ Reassignment and reuse of an area of a storage + medium (e.g., random-access memory, floppy disk, magnetic tape) + that once contained sensitive data objects. Before being + reassigned for use by a new subject, the area needs to be erased + or, in some cases, purged. [NCS04] (See: object.) + + $ obstruction + (I) A type of threat action that interrupts delivery of system + services by hindering system operations. (See: disruption.) + + Tutorial: This type of threat action includes the following + subtypes: + - "Interference": Disruption of system operations by blocking + communication of user data or control information. (See: + jamming.) + - "Overload": Hindrance of system operation by placing excess + burden on the performance capabilities of a system component. + (See: flooding.) + + $ OCSP + (I) See: Online Certificate Status Protocol. + + $ octet + (I) A data unit of eight bits. (Compare: byte.) + + Usage: This term is used in networking (especially in OSI + standards) in preference to "byte", because some systems use + "byte" for data storage units of a size other than eight bits. + + $ OFB + (N) See: output feedback. + + $ off-line attack + (I) See: secondary definition under "attack". + + $ ohnosecond + (D) That minuscule fraction of time in which you realize that your + private key has been compromised. + + Deprecated Usage: IDOCs SHOULD NOT use this term; it is a joke for + English speakers. (See: Deprecated Usage under "Green Book".) + + + + +Shirey Informational [Page 204] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ OID + (N) See: object identifier. + + $ Online Certificate Status Protocol (OCSP) + (I) An Internet protocol [R2560] used by a client to obtain from a + server the validity status and other information about a digital + certificate. (Mentioned in [X509] but not specified there.) + + Tutorial: In some applications, such as those involving high-value + commercial transactions, it may be necessary either (a) to obtain + certificate revocation status that is timelier than is possible + with CRLs or (b) to obtain other kinds of status information. OCSP + may be used to determine the current revocation status of a + digital certificate, in lieu of or as a supplement to checking + against a periodic CRL. An OCSP client issues a status request to + an OCSP server and suspends acceptance of the certificate in + question until the server provides a response. + + $ one-time pad + 1. (N) A manual encryption system in the form of a paper pad for + one-time use. + + 2. (I) An encryption algorithm in which the key is a random + sequence of symbols and each symbol is used for encryption only + one time -- i.e., used to encrypt only one plaintext symbol and + thus produce only one ciphertext symbol -- and a copy of the key + is used similarly for decryption. + + Tutorial: To ensure one-time use, the copy of the key used for + encryption is destroyed after use, as is the copy used for + decryption. This is the only encryption algorithm that is truly + unbreakable, even given unlimited resources for cryptanalysis + [Schn], but key management costs and synchronization problems make + it impractical except in special situations. + + $ one-time password, One-Time Password (OTP) + 1. (I) /not capitalized/ A "one-time password" is a simple + authentication technique in which each password is used only once + as authentication information that verifies an identity. This + technique counters the threat of a replay attack that uses + passwords captured by wiretapping. + + 2. (I) /capitalized/ "One-Time Password" is an Internet protocol + [R2289] that is based on S/KEY and uses a cryptographic hash + function to generate one-time passwords for use as authentication + information in system login and in other processes that need + protection against replay attacks. + + + + +Shirey Informational [Page 205] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ one-way encryption + (I) Irreversible transformation of plain text to cipher text, such + that the plain text cannot be recovered from the cipher text by + other than exhaustive procedures even if the cryptographic key is + known. (See: brute force, encryption.) + + $ one-way function + (I) "A (mathematical) function, f, [that] is easy to compute, but + which for a general value y in the range, it is computationally + difficult to find a value x in the domain such that f(x) = y. + There may be a few values of y for which finding x is not + computationally difficult." [X509] + + Deprecated Usage: IDOCs SHOULD NOT use this term as a synonym for + "cryptographic hash". + + $ onion routing + (I) A system that can be used to provide both (a) data + confidentiality and (b) traffic-flow confidentiality for network + packets, and also provide (c) anonymity for the source of the + packets. + + Tutorial: The source, instead of sending a packet directly to the + intended destination, sends it to an "onion routing proxy" that + builds an anonymous connection through several other "onion + routers" to the destination. The proxy defines a route through the + "onion routing network" by encapsulating the original payload in a + layered data packet called an "onion", in which each layer defines + the next hop in the route and each layer is also encrypted. Along + the route, each onion router that receives the onion peels off one + layer; decrypts that layer and reads from it the address of the + next onion router on the route; pads the remaining onion to some + constant size; and sends the padded onion to that next router. + + $ open security environment + (O) /U.S. DoD/ A system environment that meets at least one of the + following two conditions: (a) Application developers (including + maintainers) do not have sufficient clearance or authorization to + provide an acceptable presumption that they have not introduced + malicious logic. (b) Configuration control does not provide + sufficient assurance that applications and the equipment are + protected against the introduction of malicious logic prior to and + during the operation of system applications. [NCS04] (See: "first + law" under "Courtney's laws". Compare: closed security + environment.) + + + + + + +Shirey Informational [Page 206] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ open storage + (N) /U.S. Government/ "Storage of classified information within an + accredited facility, but not in General Services Administration + approved secure containers, while the facility is unoccupied by + authorized personnel." [C4009] + + $ Open Systems Interconnection (OSI) Reference Model (OSIRM) + (N) A joint ISO/ITU-T standard [I7498-1] for a seven-layer, + architectural communication framework for interconnection of + computers in networks. (See: OSIRM Security Architecture. Compare: + Internet Protocol Suite.) + + Tutorial: OSIRM-based standards include communication protocols + that are mostly incompatible with the IPS, but also include + security models, such as X.509, that are used in the Internet. + + The OSIRM layers, from highest to lowest, are (7) Application, (6) + Presentation, (5) Session, (4) Transport, (3) Network, (2) Data + Link, and (1) Physical. + + Usage: This Glossary refers to OSIRM layers by number to avoid + confusing them with IPS layers, which are referred to by name. + + Some unknown person described how the OSIRM layers correspond to + the seven deadly sins: + + 7. Wrath: Application is always angry with the mess it sees below + itself. (Hey! Who is it to be pointing fingers?) + 6. Sloth: Presentation is too lazy to do anything productive by + itself. + 5. Lust: Session is always craving and demanding what truly + belongs to Application's functionality. + 4. Avarice: Transport wants all of the end-to-end functionality. + (Of course, it deserves it, but life isn't fair.) + 3. Gluttony: (Connection-Oriented) Network is overweight and + overbearing after trying too often to eat Transport's lunch. + 2. Envy: Poor Data Link is always starved for attention. (With + Asynchronous Transfer Mode, maybe now it is feeling less + neglected.) + 1. Pride: Physical has managed to avoid much of the controversy, + and nearly all of the embarrassment, suffered by the others. + + John G. Fletcher described how the OSIRM layers correspond to Snow + White's dwarf friends: + + 7. Doc: Application acts as if it is in charge, but sometimes + muddles its syntax. + + + + +Shirey Informational [Page 207] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + 6. Sleepy: Presentation is indolent, being guilty of the sin of + Sloth. + 5. Dopey: Session is confused because its charter is not very + clear. + 4. Grumpy: Transport is irritated because Network has encroached + on Transport's turf. + 3. Happy: Network smiles for the same reason that Transport is + irritated. + 2. Sneezy: Data Link makes loud noises in the hope of attracting + attention. + 1. Bashful: Physical quietly does its work, unnoticed by the + others. + + $ operational integrity + (I) Synonym for "system integrity"; this synonym emphasizes the + actual performance of system functions rather than just the + ability to perform them. + + $ operational security + 1. (I) System capabilities, or performance of system functions, + that are needed either (a) to securely manage a system or (b) to + manage security features of a system. (Compare: operations + security (OPSEC).) + + Usage: IDOCs that use this term SHOULD state a definition because + (a) the definition provided here is general and vague and (b) the + term could easily be confused with "operations security", which is + a different concept. + + Tutorial: For example, in the context of an Internet service + provider, the term could refer to capabilities to manage network + devices in the event of attacks, simplify troubleshooting, keep + track of events that affect system integrity, help analyze sources + of attacks, and provide administrators with control over network + addresses and protocols to help mitigate the most common attacks + and exploits. [R3871] + + 2. (D) Synonym for "administrative security". + + Deprecated Definition: IDOCs SHOULD NOT use this term as a synonym + for "administrative security". Any type of security may affect + system operations; therefore, the term may be misleading. Instead, + use "administrative security", "communication security", "computer + security", "emanations security", "personnel security", "physical + security", or whatever specific type is meant. (See: security + architecture. Compare: operational integrity, OPSEC.) + + + + + +Shirey Informational [Page 208] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ operations security (OPSEC) + (I) A process to identify, control, and protect evidence of the + planning and execution of sensitive activities and operations, and + thereby prevent potential adversaries from gaining knowledge of + capabilities and intentions. (See: communications cover. Compare: + operational security.) + + $ operator + (I) A person who has been authorized to direct selected functions + of a system. (Compare: manager, user.) + + Usage: IDOCs that use this term SHOULD state a definition for it + because a system operator may or may not be treated as a "user". + + $ OPSEC + 1. (I) Abbreviation for "operations security". + + 2. (D) Abbreviation for "operational security". + + Deprecated Usage: IDOCs SHOULD NOT use this abbreviation for + "operational security" (as defined in this Glossary), because its + use for "operations security" has been well established for many + years, particular in the military community. + + $ ORA + See: organizational registration authority. + + $ Orange Book + (D) /slang/ Synonym for "Trusted Computer System Evaluation + Criteria" [CSC1, DoD1]. + + Deprecated Usage: IDOCs SHOULD NOT use this term as a synonym for + "Trusted Computer System Evaluation Criteria" [CSC1, DoD1]. + Instead, use the full, proper name of the document or, in + subsequent references, the abbreviation "TCSEC". (See: Deprecated + Usage under "Green Book".) + + $ organizational certificate + 1. (I) An X.509 public-key certificate in which the "subject" + field contains the name of an institution or set (e.g., a + business, government, school, labor union, club, ethnic group, + nationality, system, or group of individuals playing the same + role), rather than the name of an individual person or device. + (Compare: persona certificate, role certificate.) + + Tutorial: Such a certificate might be issued for one of the + following purposes: + + + + +Shirey Informational [Page 209] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + - To enable an individual to prove membership in the + organization. + - To enable an individual to represent the organization, i.e., to + act in its name and with its powers or permissions. + + 2. (O) /MISSI/ A type of MISSI X.509 public-key certificate that + is issued to support organizational message handling for the U.S. + DoD's Defense Message System. + + $ organizational registration authority (ORA) + 1. (I) /PKI/ An RA for an organization. + + 2. (O) /MISSI/ An end entity that (a) assists a PCA, CA, or SCA to + register other end entities, by gathering, verifying, and entering + data and forwarding it to the signing authority and (b) may also + assist with card management functions. An ORA is a local + administrative authority, and the term refers both to the role and + to the person who plays that role. An ORA does not sign + certificates, CRLs, or CKLs. (See: no-PIN ORA, SSO-PIN ORA, user- + PIN ORA.) + + $ origin authentication + (D) Synonym for "data origin authentication". (See: + authentication, data origin authentication.) + + Deprecated Term: IDOCs SHOULD NOT use this term; it suggests + careless use of the internationally standardized term "data origin + authentication" and also could be confused with "peer entity + authentication." + + $ origin authenticity + (D) Synonym for "data origin authentication". (See: authenticity, + data origin authentication.) + + Deprecated Term: IDOCs SHOULD NOT use this term; it suggests + careless use of the internationally standardized term "data origin + authentication" and mixes concepts in a potentially misleading + way. + + $ OSI, OSIRM + (N) See: Open Systems Interconnection Reference Model. + + $ OSIRM Security Architecture + (N) The part of the OSIRM [I7498-2] that specifies the security + services and security mechanisms that can be applied to protect + communications between two systems. (See: security architecture.) + + + + + +Shirey Informational [Page 210] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Tutorial: This part of the OSIRM includes an allocation of + security services to protocol layers. The following table shows + which security services (see definitions in this Glossary) are + permitted by the OSIRM in each of its layers. (Also, an + application process that operates above the Application Layer may + itself provide security services.) Similarly, the table suggests + which services are suitable for each IPS layer. However, + explaining and justifying these allocations is beyond the scope of + this Glossary. + + Legend for Table Entries: + O = Yes, [I7498-2] permits the service in this OSIRM layer. + I = Yes, the service can be incorporated in this IPS layer. + * = This layer subsumed by Application Layer in IPS. + + IPS Protocol Layers +-----------------------------------------+ + |Network| Net |In-| Trans | Application | + | H/W |Inter|ter| -port | | + | |-face|net| | | + OSIRM Protocol Layers +-----------------------------------------+ + | 1 | 2 | 3 | 4 | 5 | 6 | 7 | + Confidentiality +-----------------------------------------+ + - Datagram | O I | O I | O I | O I | | O * | O I | + - Selective Field | | | I | | | O * | O I | + - Traffic Flow | O | | O | | | | O | + -- Full | I | | | | | | | + -- Partial | | I | I | | | | I | + Integrity +-----------------------------------------+ + - Datagram | I | I | O I | O I | | | O I | + - Selective Field | | | I | | | | O I | + - Stream | | | O I | O I | | | O I | + Authentication +-----------------------------------------+ + - Peer Entity | | I | O I | O I | | | O I | + - Data Origin | | I | O I | O I | | | O I | + Access Control +-----------------------------------------+ + - type as appropriate | | I | O I | O I | | | O I | + Non-Repudiation +-----------------------------------------+ + - of Origin | | | | | | | O I | + - of Receipt | | | | | | | O I | + +-----------------------------------------+ + + $ OTAR + (N) See: over-the-air rekeying. + + $ OTP + (I) See: One-Time Password. + + + + + +Shirey Informational [Page 211] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ out-of-band + (I) /adjective, adverb/ Information transfer using a channel or + method that is outside (i.e., separate from or different from) the + main channel or normal method. + + Tutorial: Out-of-band mechanisms are often used to distribute + shared secrets (e.g., a symmetric key) or other sensitive + information items (e.g., a root key) that are needed to initialize + or otherwise enable the operation of cryptography or other + security mechanisms. Example: Using postal mail to distribute + printed or magnetic media containing symmetric cryptographic keys + for use in Internet encryption devices. (See: key distribution.) + + $ output feedback (OFB) + (N) A block cipher mode that modifies ECB mode to operate on + plaintext segments of variable length less than or equal to the + block length. [FP081] (See: block cipher, [SP38A].) + + Tutorial: This mode operates by directly using the algorithm's + previously generated output block as the algorithm's next input + block (i.e., by "feeding back" the output block) and combining + (exclusive OR-ing) the output block with the next plaintext + segment (of block length or less) to form the next ciphertext + segment. + + $ outside attack + (I) See: secondary definition under "attack". Compare: outsider.) + + $ outsider + (I) A user (usually a person) that accesses a system from a + position that is outside the system's security perimeter. + (Compare: authorized user, insider, unauthorized user.) + + Tutorial: The actions performed by an outsider in accessing the + system may be either authorized or unauthorized; i.e., an outsider + may act either as an authorized user or as an unauthorized user. + + $ over-the-air rekeying (OTAR) + (N) Changing a key in a remote cryptographic device by sending a + new key directly to the device via a channel that the device is + protecting. [C4009] + + $ overload + (I) /threat action/ See: secondary definition under "obstruction". + + $ P1363 + (N) See: IEEE P1363. + + + + +Shirey Informational [Page 212] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ PAA + (O) See: policy approving authority. + + $ package + (N) /Common Criteria/ A reusable set of either functional or + assurance components, combined in a single unit to satisfy a set + of identified security objectives. (Compare: protection profile.) + + Example: The seven EALs defined in Part 3 of the Common Criteria + are predefined assurance packages. + + Tutorial: A package is a combination of security requirement + components and is intended to be reusable in the construction of + either more complex packages or protection profiles and security + targets. A package expresses a set of either functional or + assurance requirements that meet some particular need, expressed + as a set of security objectives. + + $ packet + (I) A block of data that is carried from a source to a destination + through a communication channel or, more generally, across a + network. (Compare: datagram, PDU.) + + $ packet filter + (I) See: secondary definition under "filtering router". + + $ packet monkey + (D) /slang/ Someone who floods a system with packets, creating a + denial-of-service condition for the system's users. (See: + cracker.) + + Deprecated Term: It is likely that other cultures use different + metaphors for this concept. Therefore, to avoid international + misunderstanding, IDOCs SHOULD NOT use this term. (See: Deprecated + Usage under "Green Book".) + + $ pagejacking + (D) /slang/ A contraction of "Web page hijacking". A masquerade + attack in which the attacker copies (steals) a home page or other + material from the target server, rehosts the page on a server the + attacker controls, and causes the rehosted page to be indexed by + the major Web search services, thereby diverting browsers from the + target server to the attacker's server. + + Deprecated Term: IDOCs SHOULD NOT use this contraction. The term + is not listed in most dictionaries and could confuse international + readers. (See: Deprecated Usage under "Green Book".) + + + + +Shirey Informational [Page 213] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ PAN + (O) See: primary account number. + + $ PAP + (I) See: Password Authentication Protocol. + + $ parity bit + (I) A checksum that is computed on a block of bits by computing + the binary sum of the individual bits in the block and then + discarding all but the low-order bit of the sum. (See: checksum.) + + $ partitioned security mode + (N) A mode of system operation wherein all users having access to + the system have the necessary security clearances for all data + handled by the system, but some users might not have either formal + access approval or need-to-know for all the data. (See: /system + operation/ under "mode", formal access approval, need to know, + protection level, security clearance.) + + Usage: Usually abbreviated as "partitioned mode". This term was + defined in U.S. Government policy on system accreditation. + + $ PASS + (N) See: personnel authentication system string. + + $ passive attack + (I) See: secondary definition under "attack". + + $ passive user + (I) See: secondary definition under "system user". + + $ passive wiretapping + (I) A wiretapping attack that attempts only to observe a + communication flow and gain knowledge of the data it contains, but + does not alter or otherwise affect that flow. (See: wiretapping. + Compare: passive attack, active wiretapping.) + + $ password + 1a. (I) A secret data value, usually a character string, that is + presented to a system by a user to authenticate the user's + identity. (See: authentication information, challenge-response, + PIN, simple authentication.) + + 1b. (O) "A character string used to authenticate an identity." + [CSC2] + + + + + + +Shirey Informational [Page 214] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + 1c. (O) "A string of characters (letters, numbers, and other + symbols) used to authenticate an identity or to verify access + authorization." [FP140] + + 1d. (O) "A secret that a claimant memorizes and uses to + authenticate his or her identity. Passwords are typically + character strings." [SP63] + + Tutorial: A password is usually paired with a user identifier that + is explicit in the authentication process, although in some cases + the identifier may be implicit. A password is usually verified by + matching it to a stored value held by the access control system + for that identifier. + + Using a password as authentication information is based on + assuming that the password is known only by the system entity for + which the identity is being authenticated. Therefore, in a network + environment where wiretapping is possible, simple authentication + that relies on transmission of static (i.e., repetitively used) + passwords in cleartext form is inadequate. (See: one-time + password, strong authentication.) + + $ Password Authentication Protocol (PAP) + (I) A simple authentication mechanism in PPP. In PAP, a user + identifier and password are transmitted in cleartext form. [R1334] + (See: CHAP.) + + $ password sniffing + (D) /slang/ Passive wiretapping to gain knowledge of passwords. + (See: Deprecated Usage under "sniffing".) + + $ path discovery + (I) For a digital certificate, the process of finding a set of + public-key certificates that comprise a certification path from a + trusted key to that specific certificate. + + $ path validation + (I) The process of validating (a) all of the digital certificates + in a certification path and (b) the required relationships between + those certificates, thus validating the contents of the last + certificate on the path. (See: certificate validation.) + + Tutorial: To promote interoperable PKI applications in the + Internet, RFC 3280 specifies a detailed algorithm for validation + of a certification path. + + + + + + +Shirey Informational [Page 215] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ payment card + (N) /SET/ Collectively refers "to credit cards, debit cards, + charge cards, and bank cards issued by a financial institution and + which reflects a relationship between the cardholder and the + financial institution." [SET2] + + $ payment gateway + (O) /SET/ A system operated by an acquirer, or a third party + designated by an acquirer, to provide electronic commerce services + to the merchants in support of the acquirer, and which interfaces + to the acquirer to support the authorization, capture, and + processing of merchant payment messages, including payment + instructions from cardholders. [SET1, SET2] + + $ payment gateway certification authority (SET PCA) + (O) /SET/ A CA that issues digital certificates to payment + gateways and is operated on behalf of a payment card brand, an + acquirer, or another party according to brand rules. A SET PCA + issues a CRL for compromised payment gateway certificates. [SET2] + (See: PCA.) + + $ PC card + (N) A type of credit card-sized, plug-in peripheral device that + was originally developed to provide memory expansion for portable + computers, but is also used for other kinds of functional + expansion. (See: FORTEZZA, PCMCIA.) + + Tutorial: The international PC Card Standard defines a non- + proprietary form factor in three sizes -- Types I, II, and III -- + each of which have a 68-pin interface between the card and the + socket into which it plugs. All three types have the same length + and width, roughly the size of a credit card, but differ in their + thickness from 3.3 to 10.5 mm. Examples include storage modules, + modems, device interface adapters, and cryptographic modules. + + $ PCA + (D) Abbreviation of various kinds of "certification authority". + (See: Internet policy certification authority, (MISSI) policy + creation authority, (SET) payment gateway certification + authority.) + + Deprecated Usage: An IDOC that uses this abbreviation SHOULD + define it at the point of first use. + + $ PCI + (N) See: "protocol control information" under "protocol data + unit". + + + + +Shirey Informational [Page 216] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ PCMCIA + (N) Personal Computer Memory Card International Association, a + group of manufacturers, developers, and vendors, founded in 1989 + to standardize plug-in peripheral memory cards for personal + computers and now extended to deal with any technology that works + in the PC Card form factor. (See: PC card.) + + $ PDS + (N) See: protective distribution system. + + $ PDU + (N) See: protocol data unit. + + $ peer entity authentication + (I) "The corroboration that a peer entity in an association is the + one claimed." [I7498-2] (See: authentication.) + + $ peer entity authentication service + (I) A security service that verifies an identity claimed by or for + a system entity in an association. (See: authentication, + authentication service.) + + Tutorial: This service is used at the establishment of, or at + times during, an association to confirm the identity of one entity + to another, thus protecting against a masquerade by the first + entity. However, unlike data origin authentication service, this + service requires an association to exist between the two entities, + and the corroboration provided by the service is valid only at the + current time that the service is provided. (See: "relationship + between data integrity service and authentication services" under + "data integrity service"). + + $ PEM + (I) See: Privacy Enhanced Mail. + + $ penetrate + 1a. (I) Circumvent a system's security protections. (See: attack, + break, violation.) + + 1b. (I) Successfully and repeatedly gain unauthorized access to a + protected system resource. [Huff] + + $ penetration + (I) /threat action/ See: secondary definition under "intrusion". + + + + + + + +Shirey Informational [Page 217] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ penetration test + (I) A system test, often part of system certification, in which + evaluators attempt to circumvent the security features of a + system. [NCS04, SP42] (See: tiger team.) + + Tutorial: Penetration testing evaluates the relative vulnerability + of a system to attacks and identifies methods of gaining access to + a system by using tools and techniques that are available to + adversaries. Testing may be performed under various constraints + and conditions, including a specified level of knowledge of the + system design and implementation. For a TCSEC evaluation, testers + are assumed to have all system design and implementation + documentation, including source code, manuals, and circuit + diagrams, and to work under no greater constraints than those + applied to ordinary users. + + $ perfect forward secrecy + (I) For a key agreement protocol, the property that compromises + long-term keying material does not compromise session keys that + were previously derived from the long-term material. (Compare: + public-key forward secrecy.) + + Usage: Some existing RFCs use this term but either do not define + it or do not define it precisely. While preparing this Glossary, + we found this to be a muddled area. Experts did not agree. For all + practical purposes, the literature defines "perfect forward + secrecy" by stating the Diffie-Hellman-Merkle algorithm. The term + "public-key forward secrecy" (suggested by Hilarie Orman) and the + definition stated for it in this Glossary were crafted to be + compatible with current Internet documents, yet be narrow and + leave room for improved terminology. + + Challenge to the Internet security community: We need a taxonomy + of terms and definitions to cover the basic properties discussed + here for the full range of cryptographic algorithms and protocols + used in Internet Standards: + + Involvement of session keys vs. long-term keys: Experts disagree + about the basic ideas involved: + - One concept of "forward secrecy" is that, given observations of + the operation of a key establishment protocol up to time t, and + given some of the session keys derived from those protocol + runs, you cannot derive unknown past session keys or future + session keys. + - A related property is that, given observations of the protocol + and knowledge of the derived session keys, you cannot derive + one or more of the long-term private keys. + + + + +Shirey Informational [Page 218] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + - The "I" definition presented above involves a third concept of + "forward secrecy" that refers to the effect of the compromise + of long-term keys. + - All three concepts involve the idea that a compromise of "this" + encryption key is not supposed to compromise the "next" one. + There also is the idea that compromise of a single key will + compromise only the data protected by the single key. In + Internet literature, the focus has been on protection against + decryption of back traffic in the event of a compromise of + secret key material held by one or both parties to a + communication. + + Forward vs. backward: Experts are unhappy with the word "forward", + because compromise of "this" encryption key also is not supposed + to compromise the "previous" one, which is "backward" rather than + forward. In S/KEY, if the key used at time t is compromised, then + all keys used prior to that are compromised. If the "long-term" + key (i.e., the base of the hashing scheme) is compromised, then + all keys past and future are compromised; thus, you could say that + S/KEY has neither forward nor backward secrecy. + + Asymmetric cryptography vs. symmetric: Experts disagree about + forward secrecy in the context of symmetric cryptographic systems. + In the absence of asymmetric cryptography, compromise of any long- + term key seems to compromise any session key derived from the + long-term key. For example, Kerberos isn't forward secret, because + compromising a client's password (thus compromising the key shared + by the client and the authentication server) compromises future + session keys shared by the client and the ticket-granting server. + + Ordinary forward secrecy vs. "perfect" forward secret: Experts + disagree about the difference between these two. Some say there is + no difference, and some say that the initial naming was + unfortunate and suggest dropping the word "perfect". Some suggest + using "forward secrecy" for the case where one long-term private + key is compromised, and adding "perfect" for when both private + keys (or, when the protocol is multi-party, all private keys) are + compromised. + + Acknowledgements: Bill Burr, Burt Kaliski, Steve Kent, Paul Van + Oorschot, Jonathan Trostle, Michael Wiener, and, especially, + Hilarie Orman contributed ideas to this discussion. + + $ perimeter + See: security perimeter. + + + + + + +Shirey Informational [Page 219] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ periods processing + (I) A mode of system operation in which information of different + sensitivities is processed at distinctly different times by the + same system, with the system being properly purged or sanitized + between periods. (See: color change.) + + Tutorial: The security mode of operation and maximum + classification of data handled by the system is established for an + interval of time and then is changed for the following interval of + time. A period extends from the secure initialization of the + system to the completion of any purging of sensitive data handled + by the system during the period. + + $ permanent storage + (I) Non-volatile media that, once written into, can never be + completely erased. + + $ permission + 1a. (I) Synonym for "authorization". (Compare: privilege.) + + 1b. (N) An authorization or set of authorizations to perform + security-relevant functions in the context of role-based access + control. [ANSI] + + Tutorial: A permission is a positively stated authorization for + access that (a) can be associated with one or more roles and (b) + enables a user in a role to access a specified set of system + resources by causing a specific set of system actions to be + performed on the resources. + + $ persona certificate + (I) An X.509 certificate issued to a system entity that wishes to + use a persona to conceal its true identity when using PEM or other + Internet services that depend on PKI support. (See: anonymity.) + [R1422] + + Tutorial: PEM designers intended that (a) a CA issuing persona + certificates would explicitly not be vouching for the identity of + the system entity to whom the certificate is issued, (b) such + certificates would be issued only by CAs subordinate to a policy + CA having a policy stating that purpose (i.e., that would warn + relying parties that the "subject" field DN represented only a + persona and not a true, vetted user identity), and (c) the CA + would not need to maintain records binding the true identity of + the subject to the certificate. + + + + + + +Shirey Informational [Page 220] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + However, the PEM designers also intended that a CA issuing persona + certificates would establish procedures (d) to enable "the holder + of a PERSONA certificate to request that his certificate be + revoked" and (e) to ensure that it did not issue the same subject + DN to multiple users. The latter condition implies that a persona + certificate is not an organizational certificate unless the + organization has just one member or representative. + + $ personal identification number (PIN) + 1a. (I) A character string used as a password to gain access to a + system resource. (See: authentication information.) + + Example: A cryptographic token typically requires its user to + enter a PIN in order to access information stored in the token and + invoke the token's cryptographic functions. + + 1b. (O) An alphanumeric code or password used to authenticate an + identity. + + Tutorial: Despite the words "identification" and "number", a PIN + seldom serves as a user identifier, and a PIN's characters are not + necessarily all numeric. Retail banking applications use 4-digit + numeric user PINs, but the FORTEZZA PC card uses 12-character + alphanumeric SSO PINs. (See: SSO PIN, user PIN.) + + A better name for this concept would have been "personnel + authentication system string" (PASS), in which case, an + alphanumeric character string for this purpose would have been + called, obviously, a "PASSword". + + $ personal information + (I) Information about a particular person, especially information + of an intimate or critical nature, that could cause harm or pain + to that person if disclosed to unauthorized parties. Examples: + medical record, arrest record, credit report, academic transcript, + training report, job application, credit card number, Social + Security number. (See: privacy.) + + $ personality + 1. (I) Synonym for "principal". + + 2. (O) /MISSI/ A set of MISSI X.509 public-key certificates that + have the same subject DN, together with their associated private + keys and usage specifications, that is stored on a FORTEZZA PC + card to support a role played by the card's user. + + Tutorial: When a card's user selects a personality to use in a + FORTEZZA-aware application, the data determines behavior traits + + + +Shirey Informational [Page 221] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + (the personality) of the application. A card's user may have + multiple personalities on the card. Each has a "personality + label", a user-friendly character string that applications can + display to the user for selecting or changing the personality to + be used. For example, a military user's card might contain three + personalities: GENERAL HALFTRACK, COMMANDER FORT SWAMPY, and NEW + YEAR'S EVE PARTY CHAIRMAN. Each personality includes one or more + certificates of different types (such as DSA versus RSA), for + different purposes (such as digital signature versus encryption), + or with different authorizations. + + $ personnel authentication system string (PASS) + (N) See: Tutorial under "personal identification number". + + $ personnel security + (I) Procedures to ensure that persons who access a system have + proper clearance, authorization, and need-to-know as required by + the system's security policy. (See: security architecture.) + + $ PGP(trademark) + (O) See: Pretty Good Privacy(trademark). + + $ phase 1 negotiation + $ phase 2 negotiation + (I) /ISAKMP/ See: secondary definition under "Internet Security + Association and Key Management Protocol". + + $ phishing + (D) /slang/ A technique for attempting to acquire sensitive data, + such as bank account numbers, through a fraudulent solicitation in + email or on a Web site, in which the perpetrator masquerades as a + legitimate business or reputable person. (See: social + engineering.) + + Derivation: Possibly from "phony fishing"; the solicitation + usually involves some kind of lure or bait to hook unwary + recipients. (Compare: phreaking.) + + Deprecated Term: IDOCs SHOULD NOT use this term; it is not listed + in most dictionaries and could confuse international readers. + (See: Deprecated Usage under "Green Book".) + + $ Photuris + (I) A UDP-based, key establishment protocol for session keys, + designed for use with the IPsec protocols AH and ESP. Superseded + by IKE. + + + + + +Shirey Informational [Page 222] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ phreaking + (D) A contraction of "telephone breaking". An attack on or + penetration of a telephone system or, by extension, any other + communication or information system. [Raym] + + Deprecated Term: IDOCs SHOULD NOT use this contraction; it is not + listed in most dictionaries and could confuse international + readers. (See: Deprecated Usage under "Green Book".) + + $ physical destruction + (I) /threat action/ See: secondary definition under + "incapacitation". + + $ physical security + (I) Tangible means of preventing unauthorized physical access to a + system. Examples: Fences, walls, and other barriers; locks, safes, + and vaults; dogs and armed guards; sensors and alarm bells. + [FP031, R1455] (See: security architecture.) + + $ piggyback attack + (I) A form of active wiretapping in which the attacker gains + access to a system via intervals of inactivity in another user's + legitimate communication connection. Sometimes called a "between- + the-lines" attack. (See: hijack attack, man-in-the-middle attack.) + + Deprecated Usage: IDOCs that use this term SHOULD state a + definition for it because the term could confuse international + readers. + + $ PIN + (I) See: personal identification number. + + $ ping of death + (D) A denial-of-service attack that sends an improperly large ICMP + echo request packet (a "ping") with the intent of causing the + destination system to fail. (See: ping sweep, teardrop.) + + Deprecated Term: IDOCs SHOULD NOT use this term; instead, use + "ping packet overflow attack" or some other term that is specific + with regard to the attack mechanism. + + Tutorial: This attack seeks to exploit an implementation + vulnerability. The IP specification requires hosts to be prepared + to accept datagrams of up to 576 octets, but also permits IP + datagrams to be up to 65,535 octets long. If an IP implementation + does not properly handle very long IP packets, the ping packet may + overflow the input buffer and cause a fatal system error. + + + + +Shirey Informational [Page 223] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ ping sweep + (I) An attack that sends ICMP echo requests ("pings") to a range + of IP addresses, with the goal of finding hosts that can be probed + for vulnerabilities. (See: ping of death. Compare: port scan.) + + $ PKCS + (N) See: Public-Key Cryptography Standards. + + $ PKCS #5 + (N) A standard [PKC05] (see: RFC 2898) from the PKCS series; + defines a method for encrypting an octet string with a secret key + derived from a password. + + Tutorial: Although the method can be used for arbitrary octet + strings, its intended primary application in public-key + cryptography is for encrypting private keys when transferring them + from one computer system to another, as described in PKCS #8. + + $ PKCS #7 + (N) A standard [PKC07] (see: RFC 2315) from the PKCS series; + defines a syntax for data that may have cryptography applied to + it, such as for digital signatures and digital envelopes. (See: + CMS.) + + $ PKCS #10 + (N) A standard [PKC10] (see: RFC 2986) from the PKCS series; + defines a syntax for certification requests. (See: certification + request.) + + Tutorial: A PKCS #10 request contains a DN and a public key, and + may contain other attributes, and is signed by the entity making + the request. The request is sent to a CA, who converts it to an + X.509 public-key certificate (or some other form), and returns it, + possibly in PKCS #7 format. + + $ PKCS #11 + (N) A standard [PKC11] from the PKCS series; defines CAPI called + "Cryptoki" for devices that hold cryptographic information and + perform cryptographic functions. + + $ PKI + (I) See: public-key infrastructure. + + $ PKINIT + (I) Abbreviation for "Public Key Cryptography for Initial + Authentication in Kerberos" (RFC 4556). (See: Tutorial under + "Kerberos".) + + + + +Shirey Informational [Page 224] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ PKIX + 1a. (I) A contraction of "Public-Key Infrastructure (X.509)", the + name of the IETF working group that is specifying an architecture + [R3280] and set of protocols [R4210] to provide X.509-based PKI + services for the Internet. + + 1b. (I) A collective name for that Internet PKI architecture and + associated set of protocols. + + Tutorial: The goal of PKIX is to facilitate the use of X.509 + public-key certificates in multiple Internet applications and to + promote interoperability between different implementations that + use those certificates. The resulting PKI is intended to provide a + framework that supports a range of trust and hierarchy + environments and a range of usage environments. PKIX specifies (a) + profiles of the v3 X.509 public-key certificate standards and the + v2 X.509 CRL standards for the Internet, (b) operational protocols + used by relying parties to obtain information such as certificates + or certificate status, (c) management protocols used by system + entities to exchange information needed for proper management of + the PKI, and (d) information about certificate policies and CPSs, + covering the areas of PKI security not directly addressed in the + rest of PKIX. + + $ plain text + 1. (I) /noun/ Data that is input to an encryption process. (See: + plaintext. Compare: cipher text, clear text.) + + 2. (D) /noun/ Synonym for "clear text". + + Deprecated Definition: IDOCs SHOULD NOT use this term as a synonym + for "clear text". Sometimes plain text that is input to an + encryption operation is clear text, but other times plain text is + cipher text that was output from a previous encryption operation. + (See: superencryption.) + + $ plaintext + 1. (O) /noun/ Synonym for "plain text". + + 2. (I) /adjective/ Referring to plain text. Usage: Commonly used + instead of "plain-text". (Compare: ciphertext, cleartext.) + + 3. (D) /noun/ Synonym for "cleartext". + + Deprecated Definition: IDOCs SHOULD NOT use this term as a synonym + for "cleartext". Cleartext data is, by definition, not encrypted; + but plaintext data that is input to an encryption operation may be + + + + +Shirey Informational [Page 225] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + cleartext data or may be ciphertext data that was output from a + previous encryption operation. (See: superencryption.) + + $ PLI + (I) See: Private Line Interface. + + $ PMA + (N) See: policy management authority. + + $ Point-to-Point Protocol (PPP) + (I) An Internet Standard protocol (RFC 1661) for encapsulation and + full-duplex transportation of protocol data packets in OSIRM Layer + 3 over an OSIRM Layer 2 link between two peers, and for + multiplexing different Layer 3 protocols over the same link. + Includes optional negotiation to select and use a peer entity + authentication protocol to authenticate the peers to each other + before they exchange Layer 3 data. (See: CHAP, EAP, PAP.) + + $ Point-to-Point Tunneling Protocol (PPTP) + (I) An Internet client-server protocol (RFC 2637) (originally + developed by Ascend and Microsoft) that enables a dial-up user to + create a virtual extension of the dial-up link across a network by + tunneling PPP over IP. (See: L2TP.) + + Tutorial: PPP can encapsulate any IPS Network Interface Layer + protocol or OSIRM Layer 3 protocol. Therefore, PPTP does not + specify security services; it depends on protocols above and below + it to provide any needed security. PPTP makes it possible to + divorce the location of the initial dial-up server (i.e., the PPTP + Access Concentrator, the client, which runs on a special-purpose + host) from the location at which the dial-up protocol (PPP) + connection is terminated and access to the network is provided + (i.e., at the PPTP Network Server, which runs on a general-purpose + host). + + $ policy + 1a. (I) A plan or course of action that is stated for a system or + organization and is intended to affect and direct the decisions + and deeds of that entity's components or members. (See: security + policy.) + + 1b. (O) A definite goal, course, or method of action to guide and + determine present and future decisions, that is implemented or + executed within a particular context, such as within a business + unit. [R3198] + + Deprecated Abbreviation: IDOCs SHOULD NOT use "policy" as an + abbreviation of either "security policy" or "certificate policy". + + + +Shirey Informational [Page 226] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Instead, to avoid misunderstanding, use a fully qualified term, at + least at the point of first usage. + + Tutorial: The introduction of new technology to replace + traditional systems can result in new systems being deployed + without adequate policy definition and before the implications of + the new technology are fully understand. In some cases, it can be + difficult to establish policies for new technology before the + technology has been operationally tested and evaluated. Thus, + policy changes tend to lag behind technological changes, such that + either old policies impede the technical innovation, or the new + technology is deployed without adequate policies to govern its + use. + + When new technology changes the ways that things are done, new + "procedures" must be defined to establish operational guidelines + for using the technology and achieving satisfactory results, and + new "practices" must be established for managing new systems and + monitoring results. Practices and procedures are more directly + coupled to actual systems and business operations than are + polices, which tend to be more abstract. + - "Practices" define how a system is to be managed and what + controls are in place to monitor the system and detect abnormal + behavior or quality problems. Practices are established to + ensure that a system is managed in compliance with stated + policies. System audits are primarily concerned with whether or + not practices are being followed. Auditors evaluate the + controls to make sure they conform to accepted industry + standards, and then confirm that controls are in place and that + control measurements are being gathered. Audit trails are + examples of control measurements that are recorded as part of + system operations. + - "Procedures" define how a system is operated, and relate + closely to issues of what technology is used, who the operators + are, and how the system is deployed physically. Procedures + define both normal and abnormal operating circumstances. + - For every control defined by a practice statement, there should + be corresponding procedures to implement the control and + provide ongoing measurement of the control parameters. + Conversely, procedures require management practices to insure + consistent and correct operational behavior. + + $ policy approval authority + (D) /PKI/ Synonym for "policy management authority". [PAG] + + Deprecated Term: IDOCs SHOULD NOT use this term as synonym for + "policy management authority". The term suggests a limited, + passive role that is not typical of PMAs. + + + +Shirey Informational [Page 227] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ policy approving authority (PAA) + (O) /MISSI/ The top-level signing authority of a MISSI + certification hierarchy. The term refers both to that + authoritative office or role and to the person who plays that + role. (See: policy management authority, root registry.) + + Tutorial: A MISSI PAA (a) registers MISSI PCAs and signs their + X.509 public-key certificates, (b) issues CRLs but does not issue + a CKL, and (c) may issue cross-certificates to other PAAs. + + $ policy authority + (D) /PKI/ Synonym for "policy management authority". [PAG] + + Deprecated Term: IDOCs SHOULD NOT use this term as synonym for + "policy management authority". The term is unnecessarily vague and + thus may be confused with other PKI entities, such as CAs and RAs, + that enforce of apply various aspects of PKI policy. + + $ policy certification authority (Internet PCA) + (I) An X.509-compliant CA at the second level of the Internet + certification hierarchy, under the IPRA. Each PCA operates under + its published security policy (see: certificate policy, CPS) and + within constraints established by the IPRA for all PCAs. [R1422]. + (See: policy creation authority.) + + $ policy creation authority (MISSI PCA) + (O) /MISSI/ The second level of a MISSI certification hierarchy; + the administrative root of a security policy domain of MISSI users + and other, subsidiary authorities. The term refers both to that + authoritative office or role and to the person who fills that + office. (See: policy certification authority.) + + Tutorial: A MISSI PCA's certificate is issued by a PAA. The PCA + registers the CAs in its domain, defines their configurations, and + issues their X.509 public-key certificates. (The PCA may also + issue certificates for SCAs, ORAs, and other end entities, but a + PCA does not usually do this.) The PCA periodically issues CRLs + and CKLs for its domain. + + $ policy management authority (PMA) + (I) /PKI/ A person, role, or organization within a PKI that is + responsible for (a) creating or approving the content of the + certificate policies and CPSs that are used in the PKI; (b) + ensuring the administration of those policies; and (c) approving + any cross-certification or interoperability agreements with CAs + external to the PKI and any related policy mappings. The PMA may + also be the accreditor for the PKI as a whole or for some of its + + + + +Shirey Informational [Page 228] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + components or applications. [DoD9, PAG] (See: policy approving + authority.) + + Example: In the U.S. Department of Defense, an organization called + the Policy Management Authority is responsible for DoD PKI [DoD9]. + + $ policy mapping + (I) "Recognizing that, when a CA in one domain certifies a CA in + another domain, a particular certificate policy in the second + domain may be considered by the authority of the first domain to + be equivalent (but not necessarily identical in all respects) to a + particular certificate policy in the first domain." [X509] + + $ policy rule + (I) A building block of a security policy; it (a) defines a set of + system conditions and (b) specifies a set of system actions that + are to be performed if those conditions occur. [R3198] + + $ POP3 + (I) See: Post Office Protocol, version 3. + + $ POP3 APOP + (I) A POP3 command (better described as a transaction type, or + subprotocol) by which a POP3 client optionally uses a keyed hash + (based on MD5) to authenticate itself to a POP3 server and, + depending on the server implementation, to protect against replay + attacks. (See: CRAM, POP3 AUTH, IMAP4 AUTHENTICATE.) + + Tutorial: The server includes a unique time stamp in its greeting + to the client. The subsequent APOP command sent by the client to + the server contains the client's name and the hash result of + applying MD5 to a string formed from both the time stamp and a + shared secret value that is known only to the client and the + server. APOP was designed to provide an alternative to using + POP3's USER and PASS (i.e., password) command pair, in which the + client sends a cleartext password to the server. + + $ POP3 AUTH + (I) A POP3 command [R1734] (better described as a transaction + type, or subprotocol) by which a POP3 client optionally proposes a + mechanism to a POP3 server to authenticate the client to the + server and provide other security services. (See: POP3 APOP, IMAP4 + AUTHENTICATE.) + + Tutorial: If the server accepts the proposal, the command is + followed by performing a challenge-response authentication + protocol and, optionally, negotiating a protection mechanism for + + + + +Shirey Informational [Page 229] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + subsequent POP3 interactions. The security mechanisms used by POP3 + AUTH are those used by IMAP4. + + $ port scan + (I) A technique that sends client requests to a range of service + port addresses on a host. (See: probe. Compare: ping sweep.) + + Tutorial: A port scan can be used for pre-attack surveillance, + with the goal of finding an active port and subsequently + exploiting a known vulnerability of that port's service. A port + scan can also be used as a flooding attack. + + $ positive authorization + (I) The principle that a security architecture should be designed + so that access to system resources is permitted only when + explicitly granted; i.e., in the absence of an explicit + authorization that grants access, the default action shall be to + refuse access. (See: authorization, access.) + + $ POSIX + (N) Portable Operating System Interface for Computer Environments, + a standard [FP151, I9945] (originally IEEE Standard P1003.1) that + defines an operating system interface and environment to support + application portability at the source code level. It is intended + to be used by both application developers and system implementers. + + Tutorial: P1003.1 supports security functionality like that on + most UNIX systems, including discretionary access control and + privileges. IEEE Draft Standard P1003.6 specifies additional + functionality not provided in the base standard, including (a) + discretionary access control, (b) audit trail mechanisms, (c) + privilege mechanisms, (d) mandatory access control, and (e) + information label mechanisms. + + $ Post Office Protocol, version 3 (POP3) + (I) An Internet Standard protocol (RFC 1939) by which a client + workstation can dynamically access a mailbox on a server host to + retrieve mail messages that the server has received and is holding + for the client. (See: IMAP4.) + + Tutorial: POP3 has mechanisms for optionally authenticating a + client to a server and providing other security services. (See: + POP3 APOP, POP3 AUTH.) + + $ PPP + (I) See: Point-to-Point Protocol. + + + + + +Shirey Informational [Page 230] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ PPTP + (I) See: Point-to-Point Tunneling Protocol. + + $ preauthorization + (N) /PKI/ A CAW feature that enables certification requests to be + automatically validated against data provided in advance to the CA + by an authorizing entity. + + $ precedence + 1. (I) /information system/ A ranking assigned to events or data + objects that determines the relative order in which they are + processed. + + 2. (N) /communication system/ A designation assigned to a + communication (i.e., packet, message, data stream, connection, + etc.) by the originator to state the importance or urgency of that + communication versus other communications, and thus indicate to + the transmission system the relative order of handling, and + indicate to the receiver the order in which the communication is + to be noted. [F1037] (See: availability, critical, preemption.) + + Example: The "Precedence" subfield of the "Type of Service" field + of the IPv4 header supports the following designations (in + descending order of importance): 111 Network Control, 110 + Internetwork Control, 101 CRITIC/ECP (Critical Intelligence + Communication/Emergency Command Precedence), 100 Flash Override, + 011 Flash, 010 Immediate, 001 Priority, and 000 Routine. These + designations were adopted from U.S. DoD systems that existed + before ARPANET. + + $ preemption + (N) The seizure, usually automatic, of system resources that are + being used to serve a lower-precedence communication, in order to + serve immediately a higher-precedence communication. [F1037] + + $ Pretty Good Privacy(trademark) (PGP(trademark)) + (O) Trademarks of Network Associates, Inc., referring to a + computer program (and related protocols) that uses cryptography to + provide data security for electronic mail and other applications + on the Internet. (Compare: DKIM, MOSS, MSP, PEM, S/MIME.) + + Tutorial: PGP encrypts messages with a symmetric algorithm + (originally, IDEA in CFB mode), distributes the symmetric keys by + encrypting them with an asymmetric algorithm (originally, RSA), + and creates digital signatures on messages with a cryptographic + hash and an asymmetric encryption algorithm (originally, MD5 and + RSA). To establish ownership of public keys, PGP depends on the + "web of trust". + + + +Shirey Informational [Page 231] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ prevention + (I) See: secondary definition under "security". + + $ primary account number (PAN) + (O) /SET/ "The assigned number that identifies the card issuer and + cardholder. This account number is composed of an issuer + identification number, an individual account number + identification, and an accompanying check digit as defined by ISO + 7812-1985." [SET2, I7812] (See: bank identification number.) + + Tutorial: The PAN is embossed, encoded, or both on a magnetic- + strip-based credit card. The PAN identifies the issuer to which a + transaction is to be routed and the account to which it is to be + applied unless specific instructions indicate otherwise. The + authority that assigns the BIN part of the PAN is the American + Bankers Association. + + $ principal + (I) A specific identity claimed by a user when accessing a system. + + Usage: Usually understood to be an identity that is registered in + and authenticated by the system; equivalent to the notion of login + account identifier. Each principal is normally assigned to a + single user, but a single user may be assigned (or attempt to use) + more than one principal. Each principal can spawn one or more + subjects, but each subject is associated with only one principal. + (Compare: role, subject, user.) + + (I) /Kerberos/ A uniquely identified (i.e., uniquely named) client + or server instance that participates in a network communication. + + $ priority + (I) /information system/ Precedence for processing an event or + data object, determined by security importance or other factors. + (See: precedence.) + + $ privacy + 1. (I) The right of an entity (normally a person), acting in its + own behalf, to determine the degree to which it will interact with + its environment, including the degree to which the entity is + willing to share its personal information with others. (See: + HIPAA, personal information, Privacy Act of 1974. Compare: + anonymity, data confidentiality.) [FP041] + + 2. (O) "The right of individuals to control or influence what + information related to them may be collected and stored and by + whom and to whom that information may be disclosed." [I7498-2] + + + + +Shirey Informational [Page 232] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + 3. (D) Synonym for "data confidentiality". + + Deprecated Definition: IDOCs SHOULD NOT use this term as a synonym + for "data confidentiality" or "data confidentiality service", + which are different concepts. Privacy is a reason for security + rather than a kind of security. For example, a system that stores + personal data needs to protect the data to prevent harm, + embarrassment, inconvenience, or unfairness to any person about + whom data is maintained, and to protect the person's privacy. For + that reason, the system may need to provide data confidentiality + service. + + Tutorial: The term "privacy" is used for various separate but + related concepts, including bodily privacy, territorial privacy, + personal information privacy, and communication privacy. IDOCs are + expected to address only communication privacy, which in this + Glossary is defined primarily by "data confidentiality" and + secondarily by "data integrity". + + IDOCs are not expected to address information privacy, but this + Glossary provides definition 1 for that concept because personal + information privacy is often confused with communication privacy. + IDOCs are not expected to address bodily privacy or territorial + privacy, and this Glossary does not define those concepts because + they are not easily confused with communication privacy. + + $ Privacy Act of 1974 + (O) A U.S. Federal law (Section 552a of Title 5, United States + Code) that seeks to balance the U.S. Government's need to maintain + data about individuals with the rights of individuals to be + protected against unwarranted invasions of their privacy stemming + from federal agencies' collection, maintenance, use, and + disclosure of personal data. (See: privacy.) + + Tutorial: In 1974, the U.S. Congress was concerned with the + potential for abuses that could arise from the Government's + increasing use of computers to store and retrieve personal data. + Therefore, the Act has four basic policy objectives: + - To restrict disclosure of personally identifiable records + maintained by Federal agencies. + - To grant individuals increased rights of access to Federal + agency records maintained on themselves. + - To grant individuals the right to seek amendment of agency + records maintained on themselves upon a showing that the + records are not accurate, relevant, timely, or complete. + - To establish a code of "fair information practices" that + requires agencies to comply with statutory norms for + collection, maintenance, and dissemination of records. + + + +Shirey Informational [Page 233] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ Privacy Enhanced Mail (PEM) + (I) An Internet protocol to provide data confidentiality, data + integrity, and data origin authentication for electronic mail. + [R1421, R1422]. (Compare: DKIM, MOSS, MSP, PGP, S/MIME.) + + Tutorial: PEM encrypts messages with a symmetric algorithm + (originally, DES in CBC mode), provides distribution for the + symmetric keys by encrypting them with an asymmetric algorithm + (originally, RSA), and signs messages with an asymmetric + encryption algorithm over a cryptographic hash (originally, RSA + over either MD2 or MD5). To establish ownership of public keys, + PEM uses a certification hierarchy, with X.509 public-key + certificates and X.509 CRLs that are signed with an asymmetric + encryption algorithm over a cryptographic hash (originally, RSA + over MD2). + + PEM is designed to be compatible with a wide range of key + management methods, but is limited to specifying security services + only for text messages and, like MOSS, has not been widely + implemented in the Internet. + + $ private component + (I) Synonym for "private key". + + Deprecated Usage: In most cases, IDOCs SHOULD NOT use this term; + instead, to avoid confusing readers, use "private key". However, + the term MAY be used when discussing a key pair; e.g., "A key pair + has a public component and a private component." + + $ private extension + (I) See: secondary definition under "extension". + + $ private key + 1. (I) The secret component of a pair of cryptographic keys used + for asymmetric cryptography. (See: key pair, public key, secret + key.) + + 2. (O) In a public key cryptosystem, "that key of a user's key + pair which is known only by that user." [X509] + + $ Private Line Interface (PLI) + (I) The first end-to-end packet encryption system for a computer + network, developed by BBN starting in 1975 for the U.S. DoD, + incorporating U.S. Government-furnished, military-grade COMSEC + equipment (TSEC/KG-34). [B1822] (Compare: IPLI.) + + + + + + +Shirey Informational [Page 234] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ privilege + 1a. (I) /access control/ A synonym for "authorization". (See + authorization. Compare: permission.) + + 1b. (I) /computer platform/ An authorization to perform a + security-relevant function in the context of a computer's + operating system. + + $ privilege management infrastructure + (O) "The infrastructure able to support the management of + privileges in support of a comprehensive authorization service and + in relationship with a" PKI; i.e., processes concerned with + attribute certificates. [X509] + + Deprecated Usage: IDOCs SHOULD NOT use this term with this + definition. This definition is vague, and there is no consensus on + a more specific one. + + $ privileged process + (I) A computer process that is authorized (and, therefore, + trusted) to perform some security-relevant functions that ordinary + processes are not. (See: privilege, trusted process.) + + $ privileged user + (I) An user that has access to system control, monitoring, or + administration functions. (See: privilege, /UNIX/ under "root", + superuser, user.) + + Tutorial: Privileged users include the following types: + - Users with near or complete control of a system, who are + authorized to set up and administer user accounts, identifiers, + and authentication information, or are authorized to assign or + change other users' access to system resources. + - Users that are authorized to change control parameters (e.g., + network addresses, routing tables, processing priorities) on + routers, multiplexers, and other important equipment. + - Users that are authorized to monitor or perform troubleshooting + for a system's security functions, typically using special + tools and features that are not available to ordinary users. + + $ probe + (I) /verb/ A technique that attempts to access a system to learn + something about the system. (See: port scan.) + + Tutorial: The purpose of a probe may be offensive, e.g., an + attempt to gather information for circumventing the system's + protections; or the purpose may be defensive, e.g., to verify that + the system is working properly. + + + +Shirey Informational [Page 235] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ procedural security + (D) Synonym for "administrative security". + + Deprecated Term: IDOCs SHOULD NOT use this term as a synonym for + "administrative security". The term may be misleading because any + type of security may involve procedures, and procedures may be + either external to the system or internal. Instead, use + "administrative security", "communication security", "computer + security", "emanations security", "personnel security", "physical + security", or whatever specific type is meant. (See: security + architecture.) + + $ profile + See: certificate profile, protection profile. + + $ proof-of-possession protocol + (I) A protocol whereby a system entity proves to another that it + possesses and controls a cryptographic key or other secret + information. (See: zero-knowledge proof.) + + $ proprietary + (I) Refers to information (or other property) that is owned by an + individual or organization and for which the use is restricted by + that entity. + + $ protected checksum + (I) A checksum that is computed for a data object by means that + protect against active attacks that would attempt to change the + checksum to make it match changes made to the data object. (See: + digital signature, keyed hash, Tutorial under "checksum".) + + $ protective packaging + (N) "Packaging techniques for COMSEC material that discourage + penetration, reveal a penetration has occurred or was attempted, + or inhibit viewing or copying of keying material prior to the time + it is exposed for use." [C4009] (See: tamper-evident, tamper- + resistant. Compare: QUADRANT.) + + $ protection authority + (I) See: secondary definition under "Internet Protocol Security + Option". + + $ protection level + (N) /U.S. Government/ An indication of the trust that is needed in + a system's technical ability to enforce security policy for + confidentiality. (Compare: /system operation/ under "mode of + operation".) + + + + +Shirey Informational [Page 236] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Tutorial: An organization's security policy could define + protection levels that are based on comparing (a) the sensitivity + of information handled by a system to (b) the authorizations of + users that receive information from the system without manual + intervention and reliable human review. For each level, the policy + could specify security features and assurances that must be + included in any system that was intended to operate at that level. + + Example: Given some set of data objects that are classified at one + or more hierarchical levels and in one or more non-hierarchical + categories, the following table defines five protection levels for + systems that would handle that data. Beginning with PL1 and + evolving to PL5, each successive level would require stronger + features and assurances to handle the dataset. (See: clearance, + formal access approval, and need-to-know.) + + Lowest Clearance Formal Access Need-To-Know + Among All Users Approval of Users of Users + +-------------------+-------------------+-------------------+ + PL5 | Some user has no | [Does not matter.]| [Does not matter.]| + High | clearance at all. | | | + +-------------------+-------------------+-------------------+ + PL4 | All are cleared | [Does not matter.]| [Does not matter.]| + | for some data. | | | + +-------------------+-------------------+-------------------+ + PL3 | All are cleared | Some not approved | [Does not matter.]| + | for all data. | for all data. | | + +-------------------+-------------------+-------------------+ + PL2 | All are cleared | All are approved | Some don't need to| + | for all data. | for all data. | to know all data. | + +-------------------+-------------------+-------------------+ + PL1 | All are cleared | All are approved | All have a need | + Low | for all data. | for all data. | to know all data. | + +-------------------+-------------------+-------------------+ + + Each of these protection levels can be viewed as being equivalent to + one or more modes of system operation defined in this Glossary: + - PL5 is equivalent to multilevel security mode. + - PL4 is equivalent to either multilevel or compartmented + security mode, depending on the details of users' clearances. + - PL3 is equivalent to partitioned security mode. + - PL2 is equivalent to system-high security mode. + - PL1 is equivalent to dedicated security mode. + + $ protection profile + (N) /Common Criteria/ An implementation-independent set of + security requirements for a category of targets of evaluation that + + + + +Shirey Informational [Page 237] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + meet specific consumer needs. [CCIB] Example: [IDSAN]. (See: + target of evaluation. Compare: certificate profile, package.) + + Tutorial: A protection profile (PP) is the kind of document used + by consumers to specify functional requirements they want in a + product, and a security target (ST) is the kind of document used + by vendors to make functional claims about a product. + + A PP is intended to be a reusable statement of product security + needs, which are known to be useful and effective, for a set of + information technology security products that could be built. A PP + contains a set of security requirements, preferably taken from the + catalogs in Parts 2 and 3 of the Common Criteria, and should + include an EAL. A PP could be developed by user communities, + product developers, or any other parties interested in defining a + common set of requirements. + + $ protection ring + (I) One of a hierarchy of privileged operation modes of a system + that gives certain access rights to processes authorized to + operate in that mode. (See: Multics.) + + $ protective distribution system (PDS) + (N) A wireline or fiber-optic communication system used to + transmit cleartext classified information through an area of + lesser classification or control. [N7003] + + $ protocol + 1a. (I) A set of rules (i.e., formats and procedures) to implement + and control some type of association (e.g., communication) between + systems. Example: Internet Protocol. + + 1b. (I) A series of ordered computing and communication steps that + are performed by two or more system entities to achieve a joint + objective. [A9042] + + $ protocol control information (PCI) + (N) See: secondary definition under "protocol data unit". + + $ protocol data unit (PDU) + (N) A data packet that is defined for peer-to-peer transfers in a + protocol layer. + + Tutorial: A PDU consists of two disjoint subsets of data: the SDU + and the PCI. (Although these terms -- PDU, SDU, and PCI -- + originated in the OSIRM, they are also useful and permissible in + an IPS context.) + + + + +Shirey Informational [Page 238] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + - The "service data unit" (SDU) in a packet is data that the + protocol transfers between peer protocol entities on behalf of + the users of that layer's services. For Layers 1 through 6, the + layer's users are peer protocol entities at a higher layer; for + Layer 7, the users are application entities outside the scope + of the OSIRM. + - The "protocol control information" (PCI) in a packet is data + that peer protocol entities exchange between themselves to + control their joint operation of the layer. + + $ protocol suite + (I) A complementary collection of communication protocols used in + a computer network. (See: IPS, OSI.) + + $ proxy + 1. (I) A computer process that acts on behalf of a user or client. + + 2. (I) A computer process -- often used as, or as part of, a + firewall -- that relays application transactions or a protocol + between client and server computer systems, by appearing to the + client to be the server and appearing to the server to be the + client. (See: SOCKS.) + + Tutorial: In a firewall, a proxy server usually runs on a bastion + host, which may support proxies for several applications and + protocols (e.g., FTP, HTTP, and TELNET). Instead of a client in + the protected enclave connecting directly to an external server, + the internal client connects to the proxy server, which in turn + connects to the external server. The proxy server waits for a + request from inside the firewall, forwards the request to the + server outside the firewall, gets the response, then sends the + response back to the client. The proxy may be transparent to the + clients, or they may need to connect first to the proxy server, + and then use that association to also initiate a connection to the + real server. + + Proxies are generally preferred over SOCKS for their ability to + perform caching, high-level logging, and access control. A proxy + can provide security service beyond that which is normally part of + the relayed protocol, such as access control based on peer entity + authentication of clients, or peer entity authentication of + servers when clients do not have that ability. A proxy at OSIRM + Layer 7 can also provide finer-grained security service than can a + filtering router at Layer 3. For example, an FTP proxy could + permit transfers out of, but not into, a protected network. + + + + + + +Shirey Informational [Page 239] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ proxy certificate + (I) An X.509 public-key certificate derived from an end-entity + certificate, or from another proxy certificate, for the purpose of + establishing proxies and delegating authorizations in the context + of a PKI-based authentication system. [R3820] + + Tutorial: A proxy certificate has the following properties: + - It contains a critical extension that (a) identifies it as a + proxy certificate and (b) may contain a certification path + length constraint and policy constraints. + - It contains the public component of a key pair that is distinct + from that associated with any other certificate. + - It is signed by the private component of a key pair that is + associated with an end-entity certificate or another proxy + certificate. + - Its associated private key can be used to sign only other proxy + certificates (not end-entity certificates). + - Its "subject" DN is derived from its "issuer" DN and is unique. + - Its "issuer" DN is the "subject" DN of an end-entity + certificate or another proxy certificate. + + $ pseudorandom + (I) A sequence of values that appears to be random (i.e., + unpredictable) but is actually generated by a deterministic + algorithm. (See: compression, random, random number generator.) + + $ pseudorandom number generator + (I) See: secondary definition under "random number generator". + + $ public component + (I) Synonym for "public key". + + Deprecated Usage: In most cases, IDOCs SHOULD NOT use this term; + to avoid confusing readers, use "private key" instead. However, + the term MAY be used when discussing a key pair; e.g., "A key pair + has a public component and a private component." + + $ public key + 1. (I) The publicly disclosable component of a pair of + cryptographic keys used for asymmetric cryptography. (See: key + pair. Compare: private key.) + + 2. (O) In a public key cryptosystem, "that key of a user's key + pair which is publicly known." [X509] + + + + + + + +Shirey Informational [Page 240] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ public-key certificate + 1. (I) A digital certificate that binds a system entity's + identifier to a public key value, and possibly to additional, + secondary data items; i.e., a digitally signed data structure that + attests to the ownership of a public key. (See: X.509 public-key + certificate.) + + 2. (O) "The public key of a user, together with some other + information, rendered unforgeable by encipherment with the private + key of the certification authority which issued it." [X509] + + Tutorial: The digital signature on a public-key certificate is + unforgeable. Thus, the certificate can be published, such as by + posting it in a directory, without the directory having to protect + the certificate's data integrity. + + $ public-key cryptography + (I) Synonym for "asymmetric cryptography". + + $ Public-Key Cryptography Standards (PKCS) + (N) A series of specifications published by RSA Laboratories for + data structures and algorithms used in basic applications of + asymmetric cryptography. [PKCS] (See: PKCS #5 through PKCS #11.) + + Tutorial: The PKCS were begun in 1991 in cooperation with industry + and academia, originally including Apple, Digital, Lotus, + Microsoft, Northern Telecom, Sun, and MIT. Today, the + specifications are widely used, but they are not sanctioned by an + official standards organization, such as ANSI, ITU-T, or IETF. RSA + Laboratories retains sole decision-making authority over the PKCS. + + $ public-key forward secrecy (PFS) + (I) For a key-agreement protocol based on asymmetric cryptography, + the property that ensures that a session key derived from a set of + long-term public and private keys will not be compromised if one + of the private keys is compromised in the future. (See: Usage note + and other discussion under "perfect forward secrecy".) + + $ public-key Kerberos + (I) See: Tutorial under "Kerberos", PKINIT. + + $ public-key infrastructure (PKI) + 1. (I) A system of CAs (and, optionally, RAs and other supporting + servers and agents) that perform some set of certificate + management, archive management, key management, and token + management functions for a community of users in an application of + asymmetric cryptography. (See: hierarchical PKI, mesh PKI, + security management infrastructure, trust-file PKI.) + + + +Shirey Informational [Page 241] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + 2. (I) /PKIX/ The set of hardware, software, people, policies, and + procedures needed to create, manage, store, distribute, and revoke + digital certificates based on asymmetric cryptography. + + Tutorial: The core PKI functions are (a) to register users and + issue their public-key certificates, (b) to revoke certificates + when required, and (c) to archive data needed to validate + certificates at a much later time. Key pairs for data + confidentiality may be generated (and perhaps escrowed) by CAs or + RAs, but requiring a PKI client to generate its own digital + signature key pair helps maintain system integrity of the + cryptographic system, because then only the client ever possesses + the private key it uses. Also, an authority may be established to + approve or coordinate CPSs, which are security policies under + which components of a PKI operate. + + A number of other servers and agents may support the core PKI, and + PKI clients may obtain services from them, such as certificate + validation services. The full range of such services is not yet + fully understood and is evolving, but supporting roles may include + archive agent, certified delivery agent, confirmation agent, + digital notary, directory, key escrow agent, key generation agent, + naming agent who ensures that issuers and subjects have unique + identifiers within the PKI, repository, ticket-granting agent, + time-stamp agent, and validation agent. + + $ purge + 1. (I) Synonym for "erase". + + 2. (O) /U.S. Government/ Use degaussing or other methods to render + magnetically stored data unusable and irrecoverable by any means, + including laboratory methods. [C4009] (Compare: /U.S. Government/ + erase.) + + $ QUADRANT + (O) /U.S. Government/ Short name for technology and methods that + protect cryptographic equipment by making the equipment tamper- + resistant. [C4009] (Compare: protective packaging, TEMPEST.) + + Tutorial: Equipment cannot be made completely tamper-proof, but it + can be made tamper-resistant or tamper-evident. + + $ qualified certificate + (I) A public-key certificate that has the primary purpose of + identifying a person with a high level of assurance, where the + certificate meets some qualification requirements defined by an + applicable legal framework, such as the European Directive on + Electronic Signature. [R3739] + + + +Shirey Informational [Page 242] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ quick mode + (I) See: /IKE/ under "mode". + + $ RA + (I) See: registration authority. + + $ RA domains + (I) A feature of a CAW that allows a CA to divide the + responsibility for certificate requests among multiple RAs. + + Tutorial: This ability might be used to restrict access to private + authorization data that is provided with a certificate request, + and to distribute the responsibility to review and approve + certificate requests in high-volume environments. RA domains might + segregate certificate requests according to an attribute of the + certificate's subject, such as an organizational unit. + + $ RADIUS + (I) See: Remote Authentication Dial-In User Service. + + $ Rainbow Series + (O) /COMPUSEC/ A set of more than 30 technical and policy + documents with colored covers, issued by the NCSC, that discuss in + detail the TCSEC and provide guidance for meeting and applying the + criteria. (See: Green Book, Orange Book, Red Book, Yellow Book.) + + $ random + (I) In essence, "random" means "unpredictable". [SP22, Knut, + R4086] (See: cryptographic key, pseudorandom.) + - "Random sequence": A sequence in which each successive value is + obtained merely by chance and does not depend on the preceding + values of the sequence. In a random sequence of bits, each bit + is unpredictable; i.e., (a) the probability of each bit being a + "0" or "1" is 1/2, and (b) the value of each bit is independent + of any other bit in the sequence. + - "Random value": An individual value that is unpredictable; + i.e., each value in the total population of possibilities has + equal probability of being selected. + + $ random number generator + (I) A process that is invoked to generate a random sequence of + values (usually a sequence of bits) or an individual random value. + + Tutorial: There are two basic types of generators. [SP22] + - "(True) random number generator": It uses one or more non- + deterministic bit sources (e.g., electrical circuit noise, + timing of human processes such as key strokes or mouse + movements, semiconductor quantum effects, and other physical + + + +Shirey Informational [Page 243] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + phenomena) and a processing function that formats the bits, and + it outputs a sequence of values that is unpredictable and + uniformly distributed. + - "Pseudorandom number generator": It uses a deterministic + computational process (usually implemented by software) that + has one or more inputs called "seeds", and it outputs a + sequence of values that appears to be random according to + specified statistical tests. + + $ RBAC + (N) See: role-based access control, rule-based access control. + + Deprecated Usage: IDOCs that use this term SHOULD state a + definition for it because the abbreviation is ambiguous. + + $ RC2, RC4, RC6 + (N) See: Rivest Cipher #2, #4, #6. + + $ read + (I) /security model/ A system operation that causes a flow of + information from an object to a subject. (See: access mode. + Compare: write.) + + $ realm + (I) /Kerberos/ A domain consisting of a set of Kerberized clients, + Kerberized application servers, and one or more Kerberos + authentication servers and ticket-granting servers that support + the clients and applications, all operating under the same + security policy. (See: domain.) + + $ recovery + 1. (I) /cryptography/ The process of learning or obtaining + cryptographic data or plain text through cryptanalysis. (See: key + recovery, data recovery.) + + 2a. (I) /system integrity/ The process of restoring a secure state + in a system after there has been an accidental failure or a + successful attack. (See: secondary definition under "security", + system integrity.) + + 2b. (I) /system integrity/ The process of restoring an information + system's assets and operation following damage or destruction. + (See: contingency plan.) + + $ RED + 1. (N) Designation for data that consists only of clear text, and + for information system equipment items and facilities that handle + + + + +Shirey Informational [Page 244] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + clear text. Example: "RED key". (See: BCR, color change, RED/BLACK + separation. Compare: BLACK.) + + Derivation: From the practice of marking equipment with colors to + prevent operational errors. + + 2. (O) /U.S. Government/ Designation applied to information + systems, and to associated areas, circuits, components, and + equipment, "in which unencrypted national security information is + being processed." [C4009] + + $ RED/BLACK separation + (N) An architectural concept for cryptographic systems that + strictly separates the parts of a system that handle plain text + (i.e., RED information) from the parts that handle cipher text + (i.e., BLACK information). (See: BLACK, RED.) + + $ Red Book + (D) /slang/ Synonym for "Trusted Network Interpretation of the + Trusted Computer System Evaluation Criteria" [NCS05]. + + Deprecated Term: IDOCs SHOULD NOT use this term. Instead, use the + full proper name of the document or, in subsequent references, a + more conventional abbreviation, e.g., TNI-TCSEC. (See: TCSEC, + Rainbow Series, Deprecated Usage under "Green Book".) + + $ RED key + (N) A cleartext key, which is usable in its present form (i.e., it + does not need to be decrypted before being used). (See: RED. + Compare: BLACK key.) + + $ reference monitor + (I) "An access control concept that refers to an abstract machine + that mediates all accesses to objects by subjects." [NCS04] (See: + security kernel.) + + Tutorial: This concept was described in the Anderson report. A + reference monitor should be (a) complete (i.e., it mediates every + access), (b) isolated (i.e., it cannot be modified by other system + entities), and (c) verifiable (i.e., small enough to be subjected + to analysis and tests to ensure that it is correct). + + $ reflection attack + (I) An attack in which a valid data transmission is replayed to + the originator by an attacker who intercepts the original + transmission. (Compare: indirect attack, replay attack.) + + + + + +Shirey Informational [Page 245] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ reflector attack + (D) Synonym for "indirect attack". + + Deprecated Term: IDOCs SHOULD NOT use this term; it could be + confused with "reflection attack", which is a different concept. + + $ registered user + (I) A system entity that is authorized to receive a system's + products and services or otherwise access system resources. (See: + registration, user.) + + $ registration + 1. (I) /information system/ A system process that (a) initializes + an identity (of a system entity) in the system, (b) establishes an + identifier for that identity, (c) may associate authentication + information with that identifier, and (d) may issue an identifier + credential (depending on the type of authentication mechanism + being used). (See: authentication information, credential, + identifier, identity, identity proofing.) + + 2. (I) /PKI/ An administrative act or process whereby an entity's + name and other attributes are established for the first time at a + CA, prior to the CA issuing a digital certificate that has the + entity's name as the subject. (See: registration authority.) + + Tutorial: Registration may be accomplished either directly, by the + CA, or indirectly, by a separate RA. An entity is presented to the + CA or RA, and the authority either records the name(s) claimed for + the entity or assigns the entity's name(s). The authority also + determines and records other attributes of the entity that are to + be bound in a certificate (such as a public key or authorizations) + or maintained in the authority's database (such as street address + and telephone number). The authority is responsible, possibly + assisted by an RA, for verifying the entity's identity and vetting + the other attributes, in accordance with the CA's CPS. + + Among the registration issues that a CPS may address are the + following [R3647]: + - How a claimed identity and other attributes are verified. + - How organization affiliation or representation is verified. + - What forms of names are permitted, such as X.500 DN, domain + name, or IP address. + - Whether names are required to be meaningful or unique, and + within what domain. + - How naming disputes are resolved, including the role of + trademarks. + - Whether certificates are issued to entities that are not + persons. + + + +Shirey Informational [Page 246] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + - Whether a person is required to appear before the CA or RA, or + can instead be represented by an agent. + - Whether and how an entity proves possession of the private key + matching a public key. + + $ registration authority (RA) + 1. (I) An optional PKI entity (separate from the CAs) that does + not sign either digital certificates or CRLs but has + responsibility for recording or verifying some or all of the + information (particularly the identities of subjects) needed by a + CA to issue certificates and CRLs and to perform other certificate + management functions. (See: ORA, registration.) + + 2. (I) /PKIX/ An optional PKI component, separate from the CA(s). + The functions that the RA performs will vary from case to case but + may include identity authentication and name assignment, key + generation and archiving of key pairs, token distribution, and + revocation reporting. [R4210] + + Tutorial: Sometimes, a CA may perform all certificate management + functions for all end users for which the CA signs certificates. + Other times, such as in a large or geographically dispersed + community, it may be necessary or desirable to offload secondary + CA functions and delegate them to an assistant, while the CA + retains the primary functions (signing certificates and CRLs). The + tasks that are delegated to an RA by a CA may include personal + authentication, name assignment, token distribution, revocation + reporting, key generation, and archiving. + + An RA is an optional PKI entity, separate from the CA, that is + assigned secondary functions. The duties assigned to RAs vary from + case to case but may include the following: + - Verifying a subject's identity, i.e., performing personal + authentication functions. + - Assigning a name to a subject. (See: distinguished name.) + - Verifying that a subject is entitled to have the attributes + requested for a certificate. + - Verifying that a subject possesses the private key that matches + the public key requested for a certificate. + - Performing functions beyond mere registration, such as + generating key pairs, distributing tokens, handling revocation + reports, and archiving data. (Such functions may be assigned to + a PKI component that is separate from both the CA and the RA.) + + 3. (O) /SET/ "An independent third-party organization that + processes payment card applications for multiple payment card + brands and forwards applications to the appropriate financial + institutions." [SET2] + + + +Shirey Informational [Page 247] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ regrade + (I) Deliberately change the security level (especially the + hierarchical classification level) of information in an authorized + manner. (See: downgrade, upgrade.) + + $ rekey + (I) Change the value of a cryptographic key that is being used in + an application of a cryptographic system. (See: certificate + rekey.) + + Tutorial: Rekey is required at the end of a cryptoperiod or key + lifetime. + + $ reliability + (I) The ability of a system to perform a required function under + stated conditions for a specified period of time. (Compare: + availability, survivability.) + + $ reliable human review + (I) Any manual, automated, or hybrid process or procedure that + ensures that a human examines a digital object, such as text or an + image, to determine whether the object may be permitted, according + to some security policy, to be transferred across a controlled + interface. (See: guard.) + + $ relying party + (I) Synonym for "certificate user". + + Usage: Used in a legal context to mean a recipient of a + certificate who acts in reliance on that certificate. (See: ABA + Guidelines.) + + $ remanence + (I) Residual information that can be recovered from a storage + medium after clearing. (See: clear, magnetic remanence, purge.) + + $ Remote Authentication Dial-In User Service (RADIUS) + (I) An Internet protocol [R2865] for carrying dial-in users' + authentication information and configuration information between a + shared, centralized authentication server (the RADIUS server) and + a network access server (the RADIUS client) that needs to + authenticate the users of its network access ports. (See: TACACS.) + + User presents authentication and possibly other information to the + RADIUS client (e.g., health information regarding the user + device). + + + + + +Shirey Informational [Page 248] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Tutorial: A user presents authentication information and possibly + other information to the RADIUS client, and the client passes that + information to the RADIUS server. The server authenticates the + client using a shared secret value and checks the presented + information, and then returns to the client all authorization and + configuration information needed by the client to serve the user. + + $ renew + See: certificate renewal. + + $ reordering + (I) /packet/ See: secondary definition under "stream integrity + service". + + $ replay attack + (I) An attack in which a valid data transmission is maliciously or + fraudulently repeated, either by the originator or by a third + party who intercepts the data and retransmits it, possibly as part + of a masquerade attack. (See: active wiretapping, fresh, liveness, + nonce. Compare: indirect attack, reflection attack.) + + $ repository + 1. (I) A system for storing and distributing digital certificates + and related information (including CRLs, CPSs, and certificate + policies) to certificate users. (Compare: archive, directory.) + + 2. (O) "A trustworthy system for storing and retrieving + certificates or other information relevant to certificates." [DSG] + + Tutorial: A certificate is published to those who might need it by + putting it in a repository. The repository usually is a publicly + accessible, on-line server. In the FPKI, for example, the expected + repository is a directory that uses LDAP, but also may be an X.500 + Directory that uses DAP, or an HTTP server, or an FTP server that + permits anonymous login. + + $ repudiation + 1. (I) Denial by a system entity that was involved in an + association (especially a communication association that transfers + data) of having participated in the relationship. (See: + accountability, non-repudiation service.) + + 2. (I) A type of threat action whereby an entity deceives another + by falsely denying responsibility for an act. (See: deception.) + + + + + + + +Shirey Informational [Page 249] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Usage: This type of threat action includes the following subtypes: + - False denial of origin: Action whereby an originator denies + responsibility for sending data. + - False denial of receipt: Action whereby a recipient denies + receiving and possessing data. + + 3. (O) /OSIRM/ "Denial by one of the entities involved in a + communication of having participated in all or part of the + communication." [I7498-2] + + $ Request for Comment (RFC) + 1. (I) One of the documents in the archival series that is the + official channel for IDOCs and other publications of the Internet + Engineering Steering Group, the Internet Architecture Board, and + the Internet community in general. (RFC 2026, 2223) (See: Internet + Standard.) + + 2. (D) A popularly misused synonym for a document on the Internet + Standards Track, i.e., an Internet Standard, Draft Standard, or + Proposed Standard. (See: Internet Standard.) + + Deprecated Definition: IDOCs SHOULD NOT use this term with + definition 2 because many other types of documents also are + published as RFCs. + + $ residual risk + (I) The portion of an original risk or set of risks that remains + after countermeasures have been applied. (Compare: acceptable + risk, risk analysis.) + + $ restore + See: card restore. + + $ reverse engineering + (I) /threat action/ See: secondary definition under "intrusion". + + $ revocation + See: certificate revocation. + + $ revocation date + (N) /X.509/ In a CRL entry, a date-time field that states when the + certificate revocation occurred, i.e., when the CA declared the + digital certificate to be invalid. (See: invalidity date.) + + Tutorial: The revocation date may not resolve some disputes + because, in the worst case, all signatures made during the + validity period of the certificate may have to be considered + invalid. However, it may be desirable to treat a digital signature + + + +Shirey Informational [Page 250] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + as valid even though the private key used to sign was compromised + after the signing. If more is known about when the compromise + actually occurred, a second date-time, an "invalidity date", can + be included in an extension of the CRL entry. + + $ revocation list + See: certificate revocation list. + + $ revoke + (I) See: certificate revocation. + + $ RFC + (I) See: Request for Comment. + + $ Rijndael + (N) A symmetric, block cipher that was designed by Joan Daemen and + Vincent Rijmen as a candidate for the AES, and that won that + competition. [Daem] (See: Advanced Encryption Standard.) + + $ risk + 1. (I) An expectation of loss expressed as the probability that a + particular threat will exploit a particular vulnerability with a + particular harmful result. (See: residual risk.) + + 2. (O) /SET/ "The possibility of loss because of one or more + threats to information (not to be confused with financial or + business risk)." [SET2] + + Tutorial: There are four basic ways to deal with a risk [SP30]: + - "Risk avoidance": Eliminate the risk by either countering the + threat or removing the vulnerability. (Compare: "avoidance" + under "security".) + - "Risk transference": Shift the risk to another system or + entity; e.g., buy insurance to compensate for potential loss. + - "Risk limitation": Limit the risk by implementing controls that + minimize resulting loss. + - "Risk assumption": Accept the potential for loss and continue + operating the system. + + $ risk analysis + (I) An assessment process that systematically (a) identifies + valuable system resources and threats to those resources, (b) + quantifies loss exposures (i.e., loss potential) based on + estimated frequencies and costs of occurrence, and (c) + (optionally) recommends how to allocate available resources to + countermeasures so as to minimize total exposure. (See: risk + management, business-case analysis. Compare: threat analysis.) + + + + +Shirey Informational [Page 251] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Tutorial: Usually, it is financially and technically infeasible to + avoid or transfer all risks (see: "first corollary" of "second + law" under "Courtney's laws"), and some residual risks will + remain, even after all available countermeasures have been + deployed (see: "second corollary" of "second law" under + "Courtney's laws"). Thus, a risk analysis typically lists risks in + order of cost and criticality, thereby determining where + countermeasures should be applied first. [FP031, R2196] + + In some contexts, it is infeasible or inadvisable to attempt a + complete or quantitative risk analysis because needed data, time, + and expertise are not available. Instead, basic answers to + questions about threats and risks may be already built into + institutional security policies. For example, U.S. DoD policies + for data confidentiality "do not explicitly itemize the range of + expected threats" but instead "reflect an operational approach ... + by stating the particular management controls that must be used to + achieve [confidentiality] ... Thus, they avoid listing threats, + which would represent a severe risk in itself, and avoid the risk + of poor security design implicit in taking a fresh approach to + each new problem". [NRC91] + + $ risk assumption + (I) See: secondary definition under "risk". + + $ risk avoidance + (I) See: secondary definition under "risk". + + $ risk limitation + (I) See: secondary definition under "risk". + + $ risk management + 1. (I) The process of identifying, measuring, and controlling + (i.e., mitigating) risks in information systems so as to reduce + the risks to a level commensurate with the value of the assets + protected. (See: risk analysis.) + + 2. (I) The process of controlling uncertain events that may affect + information system resources. + + 3. (O) "The total process of identifying, controlling, and + mitigating information system-related risks. It includes risk + assessment; cost-benefit analysis; and the selection, + implementation, test, and security evaluation of safeguards. This + overall system security review considers both effectiveness and + efficiency, including impact on the mission and constraints due to + policy, regulations, and laws." [SP30] + + + + +Shirey Informational [Page 252] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ risk transference + (I) See: secondary definition under "risk". + + $ Rivest Cipher #2 (RC2) + (N) A proprietary, variable-key-length block cipher invented by + Ron Rivest for RSA Data Security, Inc. + + $ Rivest Cipher #4 (RC4) + (N) A proprietary, variable-key-length stream cipher invented by + Ron Rivest for RSA Data Security, Inc. + + $ Rivest Cipher #6 (RC6) + (N) A symmetric, block cipher with 128-bit or longer key length, + developed by Ron Rivest for RSA Data Security, Inc. as a candidate + for the AES. + + $ Rivest-Shamir-Adleman (RSA) + (N) An algorithm for asymmetric cryptography, invented in 1977 by + Ron Rivest, Adi Shamir, and Leonard Adleman [RSA78]. + + Tutorial: RSA uses exponentiation modulo the product of two large + prime numbers. The difficulty of breaking RSA is believed to be + equivalent to the difficulty of factoring integers that are the + product of two large prime numbers of approximately equal size. + + To create an RSA key pair, randomly choose two large prime + numbers, p and q, and compute the modulus, n = pq. Randomly choose + a number e, the public exponent, that is less than n and + relatively prime to (p-1)(q-1). Choose another number d, the + private exponent, such that ed-1 evenly divides (p-1)(q-1). The + public key is the set of numbers (n,e), and the private key is the + set (n,d). + + It is assumed to be difficult to compute the private key (n,d) + from the public key (n,e). However, if n can be factored into p + and q, then the private key d can be computed easily. Thus, RSA + security depends on the assumption that it is computationally + difficult to factor a number that is the product of two large + prime numbers. (Of course, p and q are treated as part of the + private key, or else are destroyed after computing n.) + + For encryption of a message, m, to be sent to Bob, Alice uses + Bob's public key (n,e) to compute m**e (mod n) = c. She sends c to + Bob. Bob computes c**d (mod n) = m. Only Bob knows d, so only Bob + can compute c**d (mod n) to recover m. + + To provide data origin authentication of a message, m, to be sent + to Bob, Alice computes m**d (mod n) = s, where (d,n) is Alice's + + + +Shirey Informational [Page 253] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + private key. She sends m and s to Bob. To recover the message that + only Alice could have sent, Bob computes s**e (mod n) = m, where + (e,n) is Alice's public key. + + To ensure data integrity in addition to data origin authentication + requires extra computation steps in which Alice and Bob use a + cryptographic hash function h (see: digital signature). Alice + computes the hash value h(m) = v, and then encrypts v with her + private key to get s. She sends m and s. Bob receives m' and s', + either of which might have been changed from the m and s that + Alice sent. To test this, he decrypts s' with Alice's public key + to get v'. He then computes h(m') = v". If v' equals v", Bob is + assured that m' is the same m that Alice sent. + + $ robustness + (N) See: level of robustness. + + $ role + 1. (I) A job function or employment position to which people or + other system entities may be assigned in a system. (See: role- + based access control. Compare: duty, billet, principal, user.) + + 2. (O) /Common Criteria/ A pre-defined set of rules establishing + the allowed interactions between a user and the TOE. + + $ role-based access control + (I) A form of identity-based access control wherein the system + entities that are identified and controlled are functional + positions in an organization or process. [Sand] (See: + authorization, constraint, identity, principal, role.) + + Tutorial: Administrators assign permissions to roles as needed to + perform functions in the system. Administrators separately assign + user identities to roles. When a user accesses the system in an + identity (for which the user has been registered) and initiates a + session using a role (to which the user has been assigned), then + the permissions that have been assigned to the role are available + to be exercised by the user. + + The following diagram shows that role-based access control + involves five different relationships: (a) administrators assign + identities to roles, (b) administrators assign permissions to + roles, (c) administrators assign roles to roles, (d) users select + identities in sessions, and (e) users select roles in sessions. + Security policies may define constraints on these assignments and + selections. + + + + + +Shirey Informational [Page 254] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + (c) Permission Inheritance Assignments (i.e., Role Hierarchy) + [Constraints] + +=====+ + | | + (a) Identity v v (b) Permission + +----------+ Assignments +-------+ Assignments +----------+ + |Identities|<=============>| Roles |<=============>|Permissions| + +----------+ [Constraints] +-------+ [Constraints] +----------+ + | | ^ ^ + | | +-----------+ | | +---------------------+ + | | | +-------+ | | | | Legend | + | +====>|Session|=====+ | | | + | | +-------+ | | | One-to-One | + | | ... | | | =================== | + | | +-------+ | | | | + +========>|Session|=========+ | One-to-Many | + (d) Identity | +-------+ | (e) Role | ==================> | + Selections | | Selections | | + [Constraints]| Access |[Constraints] | Many-to-Many | + | Sessions | | <=================> | + +-----------+ +---------------------+ + + $ role certificate + (I) An organizational certificate that is issued to a system + entity that is a member of the set of users that have identities + that are assigned to the same role. (See: role-based access + control.) + + $ root, root CA + 1. (I) /PKI/ A CA that is directly trusted by an end entity. (See: + trust anchor, trusted CA.) + + 2. (I) /hierarchical PKI/ The CA that is the highest level (most + trusted) CA in a certification hierarchy; i.e., the authority upon + whose public key all certificate users base their validation of + certificates, CRLs, certification paths, and other constructs. + (See: top CA.) + + Tutorial: The root CA in a certification hierarchy issues public- + key certificates to one or more additional CAs that form the + second-highest level. Each of these CAs may issue certificates to + more CAs at the third-highest level, and so on. To initialize + operation of a hierarchical PKI, the root's initial public key is + securely distributed to all certificate users in a way that does + not depend on the PKI's certification relationships, i.e., by an + out-of-band procedure. The root's public key may be distributed + simply as a numerical value, but typically is distributed in a + self-signed certificate in which the root is the subject. The + + + +Shirey Informational [Page 255] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + root's certificate is signed by the root itself because there is + no higher authority in a certification hierarchy. The root's + certificate is then the first certificate in every certification + path. + + 3. (I) /DNS/ The base of the tree structure that defines the name + space for the Internet DNS. (See: domain name.) + + 4. (O) /MISSI/ A name previously used for a MISSI policy creation + authority, which is not a root as defined above for general usage, + but is a CA at the second level of the MISSI hierarchy, + immediately subordinate to a MISSI policy approving authority. + + 5. (O) /UNIX/ A user account (a.k.a. "superuser") that has all + privileges (including all security-related privileges) and thus + can manage the system and its other user accounts. + + $ root certificate + 1. (I) /PKI/ A certificate for which the subject is a root. (See: + trust anchor certificate, trusted certificate.) + + 2. (I) /hierarchical PKI/ The self-signed public-key certificate + at the top of a certification hierarchy. + + $ root key + (I) /PKI/ A public key for which the matching private key is held + by a root. (See: trust anchor key, trusted key.) + + $ root registry + (O) /MISSI/ A name previously used for a MISSI PAA. + + $ ROT13 + (I) See: secondary definition under "Caesar cipher". + + $ router + 1a. (I) /IP/ A networked computer that forwards IP packets that + are not addressed to the computer itself. (Compare: host.) + + 1b. (I) /IPS/ A gateway that operates in the IPS Internet Layer to + connect two or more subnetworks. + + 1c. (N) /OSIRM/ A computer that is a gateway between two networks + at OSIRM Layer 3 and that relays and directs data packets through + that internetwork. (Compare: bridge, proxy.) + + $ RSA + (N) See: Rivest-Shamir-Adleman. + + + + +Shirey Informational [Page 256] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ rule + See: policy rule. + + $ rule-based security policy + (I) "A security policy based on global rules [i.e., policy rules] + imposed for all users. These rules usually rely on comparison of + the sensitivity of the resource being accessed and the possession + of corresponding attributes of users, a group of users, or + entities acting on behalf of users." [I7498-2] (Compare: identity- + based security policy, policy rule, RBAC.) + + $ rules of behavior + (I) A body of security policy that has been established and + implemented concerning the responsibilities and expected behavior + of entities that have access to a system. (Compare: [R1281].) + + Tutorial: For persons employed by a corporation or government, the + rules might cover such matters as working at home, remote access, + use of the Internet, use of copyrighted works, use of system + resources for unofficial purpose, assignment and limitation of + system privileges, and individual accountability. + + $ S field + (D) See: Security Level field. + + $ S-BGP + (I) See: Secure BGP. + + $ S-HTTP + (I) See: Secure Hypertext Transfer Protocol. + + $ S/Key + (I) A security mechanism that uses a cryptographic hash function + to generate a sequence of 64-bit, one-time passwords for remote + user login. [R1760] + + Tutorial: The client generates a one-time password by applying the + MD4 cryptographic hash function multiple times to the user's + secret key. For each successive authentication of the user, the + number of hash applications is reduced by one. (Thus, an intruder + using wiretapping cannot compute a valid password from knowledge + of one previously used.) The server verifies a password by hashing + the currently presented password (or initialization value) one + time and comparing the hash result with the previously presented + password. + + $ S/MIME + (I) See: Secure/MIME. + + + +Shirey Informational [Page 257] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ SAD + (I) See: Security Association Database. + + $ safety + (I) The property of a system being free from risk of causing harm + (especially physical harm) to its system entities. (Compare: + security.) + + $ SAID + (I) See: security association identifier. + + $ salami swindle + (D) /slang/ "Slicing off a small amount from each transaction. + This kind of theft was made worthwhile by automation. Given a high + transaction flow, even rounding down to the nearest cent and + putting the 'extra' in a bogus account can be very profitable." + [NCSSG] + + Deprecated Term: It is likely that other cultures use different + metaphors for this concept. Therefore, to avoid international + misunderstanding, IDOCs SHOULD NOT use this term. (See: Deprecated + Usage under "Green Book".) + + $ salt + (I) A data value used to vary the results of a computation in a + security mechanism, so that an exposed computational result from + one instance of applying the mechanism cannot be reused by an + attacker in another instance. (Compare: initialization value.) + + Example: A password-based access control mechanism might protect + against capture or accidental disclosure of its password file by + applying a one-way encryption algorithm to passwords before + storing them in the file. To increase the difficulty of off-line, + dictionary attacks that match encrypted values of potential + passwords against a copy of the password file, the mechanism can + concatenate each password with its own random salt value before + applying the one-way function. + + $ SAML + (N) See: Security Assertion Markup Language (SAML). + + $ sandbox + (I) A restricted, controlled execution environment that prevents + potentially malicious software, such as mobile code, from + accessing any system resources except those for which the software + is authorized. + + + + + +Shirey Informational [Page 258] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ sanitize + 1. (I) Delete sensitive data from a file, device, or system. (See: + erase, zeroize.) + + 2. (I) Modify data so as to be able either (a) to completely + declassify it or (b) to downgrade it to a lower security level. + + $ SAP + (O) See: special access program. + + $ SASL + (I) See: Simple Authentication and Security Layer. + + $ SCA + (I) See: subordinate certification authority. + + $ scavenging + (I) /threat action/ See: secondary definition under "exposure". + + $ SCI + (O) See: sensitive compartmented information. + + $ SCIF + (O) See: sensitive compartmented information facility. + + $ SCOMP + (N) Secure COMmunications Processor; an enhanced, MLS version of + the Honeywell Level 6 minicomputer. It was the first system to be + rated in TCSEC Class A1. (See: KSOS.) + + $ screen room + (D) /slang/ Synonym for "shielded enclosure" in the context of + electromagnetic emanations. (See: EMSEC, TEMPEST.) + + Deprecated Term: To avoid international misunderstanding, IDOCs + SHOULD NOT use this term. + + $ screening router + (I) Synonym for "filtering router". + + $ script kiddy + (D) /slang/ A cracker who is able to use existing attack + techniques (i.e., to read scripts) and execute existing attack + software, but is unable to invent new exploits or manufacture the + tools to perform them; pejoratively, an immature or novice + cracker. + + + + + +Shirey Informational [Page 259] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Deprecated Term: It is likely that other cultures use different + metaphors for this concept. Therefore, to avoid international + misunderstanding, IDOCs SHOULD NOT use this term. (See: Deprecated + Usage under "Green Book".) + + $ SDE + (N) See: Secure Data Exchange. + + $ SDNS + (O) See: Secure Data Network System. + + $ SDU + (N) See: "service data unit" under "protocol data unit". + + $ seal + 1. (I) To use asymmetric cryptography to encrypt plain text with a + public key in such a way that only the holder of the matching + private key can learn what was the plain text. [Chau] (Compare: + shroud, wrap.) + + Deprecated Usage: An IDOC SHOULD NOT use this term with definition + 1 unless the IDOC includes the definition, because the definition + is not widely known and the concept can be expressed by using + other, standard terms. Instead, use "salt and encrypt" or other + terminology that is specific with regard to the mechanism being + used. + + Tutorial: The definition does *not* say "only the holder of the + matching private key can decrypt the ciphertext to learn what was + the plaintext"; sealing is stronger than that. If Alice simply + encrypts a plaintext P with a public key K to produce ciphertext C + = K(P), then if Bob guesses that P = X, Bob could verify the guess + by checking whether K(P) = K(X). To "seal" P and block Bob's + guessing attack, Alice could attach a long string R of random bits + to P before encrypting to produce C = K(P,R); if Bob guesses that + P = X, Bob can only test the guess by also guessing R. (See: + salt.) + + 2. (D) To use cryptography to provide data integrity service for a + data object. (See: sign.) + + Deprecated Definition: IDOCs SHOULD NOT use this term with + definition 2. Instead, use a term that is more specific with + regard to the mechanism used to provide the data integrity + service; e.g., use "sign" when the mechanism is digital signature. + + + + + + +Shirey Informational [Page 260] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ secret + 1a. (I) /adjective/ The condition of information being protected + from being known by any system entities except those that are + intended to know it. (See: data confidentiality.) + + 1b. (I) /noun/ An item of information that is protected thusly. + + Usage: This term applies to symmetric keys, private keys, and + passwords. + + $ secret key + (D) A key that is kept secret or needs to be kept secret. + + Deprecated Term: IDOCs SHOULD NOT use this term; it mixes concepts + in a potentially misleading way. In the context of asymmetric + cryptography, IDOCs SHOULD use "private key". In the context of + symmetric cryptography, the adjective "secret" is unnecessary + because all keys must be kept secret. + + $ secret-key cryptography + (D) Synonym for "symmetric cryptography". + + Deprecated Term: IDOCs SHOULD NOT use this term; it could be + confused with "asymmetric cryptography", in which the private key + is kept secret. + + Derivation: Symmetric cryptography is sometimes called "secret-key + cryptography" because entities that share the key, such as the + originator and the recipient of a message, need to keep the key + secret from other entities. + + $ Secure BGP (S-BGP) + (I) A project of BBN Technologies, sponsored by the U.S. DoD's + Defense Advanced Research Projects Agency, to design and + demonstrate an architecture to secure the Border Gateway Protocol + (RFC 1771) and to promote deployment of that architecture in the + Internet. + + Tutorial: S-BGP incorporates three security mechanisms: + - A PKI supports authentication of ownership of IP address + blocks, autonomous system (AS) numbers, an AS's identity, and a + BGP router's identity and its authorization to represent an AS. + This PKI parallels and takes advantage of the Internet's + existing IP address and AS number assignment system. + - A new, optional, BGP transitive path attribute carries digital + signatures (in "attestations") covering the routing information + in a BGP UPDATE. These signatures along with certificates from + the S-BGP PKI enable the receiver of a BGP routing UPDATE to + + + +Shirey Informational [Page 261] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + validate the attribute and gain trust in the address prefixes + and path information that it contains. + - IPsec provides data and partial sequence integrity, and enables + BGP routers to authenticate each other for exchanges of BGP + control traffic. + + $ Secure Data Exchange (SDE) + (N) A LAN security protocol defined by the IEEE 802.10 standard. + + $ Secure Data Network System (SDNS) + (O) An NSA program that developed security protocols for + electronic mail (see: MSP), OSIRM Layer 3 (see: SP3), OSIRM Layer + 4 (see: SP4), and key establishment (see: KMP). + + $ secure distribution + (I) See: trusted distribution. + + $ Secure Hash Algorithm (SHA) + (N) A cryptographic hash function (specified in SHS) that produces + an output (see: "hash result") -- of selectable length of either + 160, 224, 256, 384, or 512 bits -- for input data of any length < + 2**64 bits. + + $ Secure Hash Standard (SHS) + (N) The U.S. Government standard [FP180] that specifies SHA. + + $ Secure Hypertext Transfer Protocol (S-HTTP) + (I) An Internet protocol [R2660] for providing client-server + security services for HTTP communications. (Compare: https.) + + Tutorial: S-HTTP was originally specified by CommerceNet, a + coalition of businesses interested in developing the Internet for + commercial uses. Several message formats may be incorporated into + S-HTTP clients and servers, particularly CMS and MOSS. S-HTTP + supports choice of security policies, key management mechanisms, + and cryptographic algorithms through option negotiation between + parties for each transaction. S-HTTP supports modes of operation + for both asymmetric and symmetric cryptography. S-HTTP attempts to + avoid presuming a particular trust model, but it attempts to + facilitate multiply rooted, hierarchical trust and anticipates + that principals may have many public-key certificates. + + $ Secure/MIME (S/MIME) + (I) Secure/Multipurpose Internet Mail Extensions, an Internet + protocol [R3851] to provide encryption and digital signatures for + Internet mail messages. + + + + + +Shirey Informational [Page 262] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ secure multicast + (I) Refers generally to providing security services for multicast + groups of various types (e.g., 1-to-N and M-to-N) and to classes + of protocols used to protect multicast packets. + + Tutorial: Multicast applications include video broadcast and + multicast file transfer, and many of these applications require + network security services. The Multicast Security Reference + Framework [R3740] covers three functional areas: + - Multicast data handling: Security-related treatment of + multicast data by the sender and the receiver. + - Group key management: Secure distribution and refreshment of + keying material. (See: Group Domain of Interpretation.) + - Multicast security policy: Policy translation and + interpretation across the multiple administrative domains that + typically are spanned by a multicast application. + + $ Secure Shell(trademark) (SSH(trademark)) + (N) Refers to a protocol for secure remote login and other secure + network services. + + Usage: On the Web site of SSH Communication Security Corporation, + at http://www.ssh.com/legal_notice.html, it says, "SSH [and] the + SSH logo ... are either trademarks or registered trademarks of + SSH." This Glossary seeks to make readers aware of this trademark + claim but takes no position on its validity. + + Tutorial: SSH has three main parts: + - Transport layer protocol: Provides server authentication, + confidentiality, and integrity; and can optionally provide + compression. This layer typically runs over a TCP connection, + but might also run on top of any other reliable data stream. + - User authentication protocol: Authenticates the client-side + user to the server. It runs over the transport layer protocol. + - Connection protocol: Multiplexes the encrypted tunnel into + several logical channels. It runs over the user authentication + protocol. + + $ Secure Sockets Layer (SSL) + (N) An Internet protocol (originally developed by Netscape + Communications, Inc.) that uses connection-oriented end-to-end + encryption to provide data confidentiality service and data + integrity service for traffic between a client (often a web + browser) and a server, and that can optionally provide peer entity + authentication between the client and the server. (See: Transport + Layer Security.) + + + + + +Shirey Informational [Page 263] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Tutorial: SSL has two layers; SSL's lower layer, the SSL Record + Protocol, is layered on top of an IPS Transport-Layer protocol and + encapsulates protocols that run in the upper layer. The upper- + layer protocols are the three SSL management protocols -- SSL + Handshake Protocol, SSL Change Cipher Spec Protocol, or SSL Alert + Protocol -- and some Application-Layer protocol (e.g., HTTP). + + The SSL management protocols provide asymmetric cryptography for + server authentication (verifying the server's identity to the + client) and optional client authentication (verifying the client's + identity to the server), and also enable them, before the + application protocol transmits or receives data, to negotiate a + symmetric encryption algorithm and secret session key (to use for + data confidentiality service) and a keyed hash (to use for data + integrity service). + + SSL is independent of the application it encapsulates, and any + application can layer on top of SSL transparently. However, many + Internet applications might be better served by IPsec. + + $ secure state + 1a. (I) A system condition in which the system is in conformance + with the applicable security policy. (Compare: clean system, + transaction.) + + 1b. (I) /formal model/ A system condition in which no subject can + access any object in an unauthorized manner. (See: secondary + definition under "Bell-LaPadula model".) + + $ security + 1a. (I) A system condition that results from the establishment and + maintenance of measures to protect the system. + + 1b. (I) A system condition in which system resources are free from + unauthorized access and from unauthorized or accidental change, + destruction, or loss. (Compare: safety.) + + 2. (I) Measures taken to protect a system. + + Tutorial: Parker [Park] suggests that providing a condition of + system security may involve the following six basic functions, + which overlap to some extent: + - "Deterrence": Reducing an intelligent threat by discouraging + action, such as by fear or doubt. (See: attack, threat action.) + - "Avoidance": Reducing a risk by either reducing the value of + the potential loss or reducing the probability that the loss + will occur. (See: risk analysis. Compare: "risk avoidance" + under "risk".) + + + +Shirey Informational [Page 264] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + - "Prevention": Impeding or thwarting a potential security + violation by deploying a countermeasure. + - "Detection": Determining that a security violation is + impending, is in progress, or has recently occurred, and thus + make it possible to reduce the potential loss. (See: intrusion + detection.) + - "Recovery": Restoring a normal state of system operation by + compensating for a security violation, possibly by eliminating + or repairing its effects. (See: contingency plan, main entry + for "recovery".) + - "Correction": Changing a security architecture to eliminate or + reduce the risk of reoccurrence of a security violation or + threat consequence, such as by eliminating a vulnerability. + + $ security architecture + (I) A plan and set of principles that describe (a) the security + services that a system is required to provide to meet the needs of + its users, (b) the system components required to implement the + services, and (c) the performance levels required in the + components to deal with the threat environment (e.g., [R2179]). + (See: defense in depth, IATF, OSIRM Security Architecture, + security controls, Tutorial under "security policy".) + + Tutorial: A security architecture is the result of applying the + system engineering process. A complete system security + architecture includes administrative security, communication + security, computer security, emanations security, personnel + security, and physical security. A complete security architecture + needs to deal with both intentional, intelligent threats and + accidental threats. + + $ Security Assertion Markup Language (SAML) + (N) A protocol consisting of XML-based request and response + message formats for exchanging security information, expressed in + the form of assertions about subjects, between on-line business + partners. [SAML] + + $ security association + 1. (I) A relationship established between two or more entities to + enable them to protect data they exchange. (See: association, + ISAKMP, SAD. Compare: session.) + + Tutorial: The relationship is represented by a set of data that is + shared between the entities and is agreed upon and considered a + contract between them. The data describes how the associated + entities jointly use security services. The relationship is used + to negotiate characteristics of security mechanisms, but the + + + + +Shirey Informational [Page 265] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + relationship is usually understood to exclude the mechanisms + themselves. + + 2. (I) /IPsec/ A simplex (uni-directional) logical connection + created for security purposes and implemented with either AH or + ESP (but not both). The security services offered by a security + association depend on the protocol (AH or ESP), the IPsec mode + (transport or tunnel), the endpoints, and the election of optional + services within the protocol. A security association is identified + by a triple consisting of (a) a destination IP address, (b) a + protocol (AH or ESP) identifier, and (c) a Security Parameter + Index. + + 3. (O) "A set of policy and cryptographic keys that provide + security services to network traffic that matches that policy". + [R3740] (See: cryptographic association, group security + association.) + + 4. (O) "The totality of communications and security mechanisms and + functions (e.g., communications protocols, security protocols, + security mechanisms and functions) that securely binds together + two security contexts in different end systems or relay systems + supporting the same information domain." [DoD6] + + $ Security Association Database (SAD) + (I) /IPsec/ In an IPsec implementation that operates in a network + node, a database that contains parameters to describe the status + and operation of each of the active security associations that the + node has established with other nodes. Separate inbound and + outbound SADs are needed because of the directionality of IPsec + security associations. [R4301] (Compare: SPD.) + + $ security association identifier (SAID) + (I) A data field in a security protocol (such as NLSP or SDE), + used to identify the security association to which a PDU is bound. + The SAID value is usually used to select a key for decryption or + authentication at the destination. (See: Security Parameter + Index.) + + $ security assurance + 1. (I) An attribute of an information system that provides grounds + for having confidence that the system operates such that the + system's security policy is enforced. (Compare: trust.) + + 2. (I) A procedure that ensures a system is developed and operated + as intended by the system's security policy. + + + + + +Shirey Informational [Page 266] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + 3. (D) "The degree of confidence one has that the security + controls operate correctly and protect the system as intended." + [SP12] + + Deprecated Definition: IDOCs SHOULD NOT use definition 3; it is a + definition for "assurance level" rather than for "assurance". + + 4. (D) /U.S. Government, identity authentication/ The (a) "degree + of confidence in the vetting process used to establish the + identity of the individual to whom the [identity] credential was + issued" and the (b) "degree of confidence that the individual who + uses the credential is the individual to whom the credential was + issued". [M0404] + + Deprecated Definition: IDOCs SHOULD NOT use definition 4; it mixes + concepts in a potentially misleading way. Part "a" is a definition + for "assurance level" (rather than "security assurance") of an + identity registration process; and part "b" is a definition for + "assurance level" (rather than "security assurance") of an + identity authentication process. Also, the processes of + registration and authentication should be defined and designed + separately to ensure clarity in certification. + + $ security audit + (I) An independent review and examination of a system's records + and activities to determine the adequacy of system controls, + ensure compliance with established security policy and procedures, + detect breaches in security services, and recommend any changes + that are indicated for countermeasures. [I7498-2, NCS01] (Compare: + accounting, intrusion detection.) + + Tutorial: The basic audit objective is to establish accountability + for system entities that initiate or participate in security- + relevant events and actions. Thus, means are needed to generate + and record a security audit trail and to review and analyze the + audit trail to discover and investigate security violations. + + $ security audit trail + (I) A chronological record of system activities that is sufficient + to enable the reconstruction and examination of the sequence of + environments and activities surrounding or leading to an + operation, procedure, or event in a security-relevant transaction + from inception to final results. [NCS04] (See: security audit.) + + $ security by obscurity + (O) Attempting to maintain or increase security of a system by + keeping secret the design or construction of a security mechanism. + + + + +Shirey Informational [Page 267] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Tutorial: This approach has long been discredited in cryptography, + where the phrase refers to trying to keep an algorithm secret, + rather than just concealing the keys [Schn]. One must assume that + mass-produced or widely fielded cryptographic devices eventually + will be lost or stolen and, therefore, that the algorithms will be + reverse engineered and become known to the adversary. Thus, one + should rely on only those algorithms and protocols that are strong + enough to have been published widely, and have been peer reviewed + for long enough that their flaws have been found and removed. For + example, NIST used a long, public process to select AES to replace + DES. + + In computer and network security, the principle of "no security by + obscurity" also applies to security mechanisms other than + cryptography. For example, if the design and implementation of a + protocol for access control are strong, then reading the + protocol's source code should not enable you to find a way to + evade the protection and penetrate the system. + + $ security class + (D) Synonym for "security level". + + Deprecated Term: IDOCs SHOULD NOT use this term. Instead, use + "security level", which is more widely established and understood. + + $ security clearance + (I) A determination that a person is eligible, under the standards + of a specific security policy, for authorization to access + sensitive information or other system resources. (See: clearance + level.) + + $ security compromise + (I) A security violation in which a system resource is exposed, or + is potentially exposed, to unauthorized access. (Compare: data + compromise, exposure, violation.) + + $ security controls + (N) The management, operational, and technical controls + (safeguards or countermeasures) prescribed for an information + system which, taken together, satisfy the specified security + requirements and adequately protect the confidentiality, + integrity, and availability of the system and its information. + [FP199] (See: security architecture.) + + $ security doctrine + (I) A specified set of procedures or practices that direct or + provide guidance for how to comply with security policy. (Compare: + security mechanism, security policy.) + + + +Shirey Informational [Page 268] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Tutorial: Security policy and security doctrine are closely + related. However, policy deals mainly with strategy, and doctrine + deals with tactics. + + Security doctrine is often understood to refer mainly to + administrative security, personnel security, and physical + security. For example, security mechanisms and devices that + implement them are normally designed to operate in a limited range + of environmental and administrative conditions, and these + conditions must be met to complement and ensure the technical + protection afforded by the hardware, firmware, and software in the + devices. Security doctrine specifies how to achieve those + conditions. (See: "first law" under "Courtney's laws".) + + $ security domain + (I) See: domain. + + $ security environment + (I) The set of external entities, procedures, and conditions that + affect secure development, operation, and maintenance of a system. + (See: "first law" under "Courtney's laws".) + + $ security event + (I) An occurrence in a system that is relevant to the security of + the system. (See: security incident.) + + Tutorial: The term covers both events that are security incidents + and those that are not. In a CA workstation, for example, a list + of security events might include the following: + - Logging an operator into or out of the system. + - Performing a cryptographic operation, e.g., signing a digital + certificate or CRL. + - Performing a cryptographic card operation: creation, insertion, + removal, or backup. + - Performing a digital certificate lifecycle operation: rekey, + renewal, revocation, or update. + - Posting a digital certificate to an X.500 Directory. + - Receiving a key compromise notification. + - Receiving an improper certification request. + - Detecting an alarm condition reported by a cryptographic + module. + - Failing a built-in hardware self-test or a software system + integrity check. + + $ security fault analysis + (I) A security analysis, usually performed on hardware at the + level of gate logic, gate-by-gate, to determine the security + properties of a device when a hardware fault is encountered. + + + +Shirey Informational [Page 269] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ security function + (I) A function in a system that is relevant to the security of the + system; i.e., a system function that must operate correctly to + ensure adherence to the system's security policy. + + $ security gateway + 1. (I) An internetwork gateway that separates trusted (or + relatively more trusted) hosts on one side from untrusted (or less + trusted) hosts on the other side. (See: firewall and guard.) + + 2. (O) /IPsec/ "An intermediate system that implements IPsec + protocols." [R4301] + + Tutorial: IPsec's AH or ESP can be implemented on a gateway + between a protected network and an unprotected network, to provide + security services to the protected network's hosts when they + communicate across the unprotected network to other hosts and + gateways. + + $ security incident + 1. (I) A security event that involves a security violation. (See: + CERT, security event, security intrusion, security violation.) + + Tutorial: In other words, a security event in which the system's + security policy is disobeyed or otherwise breached. + + 2. (D) "Any adverse event [that] compromises some aspect of + computer or network security." [R2350] + + Deprecated Definition: IDOCs SHOULD NOT use definition 2 because + (a) a security incident may occur without actually being harmful + (i.e., adverse) and because (b) this Glossary defines "compromise" + more narrowly in relation to unauthorized access. + + 3. (D) "A violation or imminent threat of violation of computer + security policies, acceptable use policies, or standard computer + security practices." [SP61] + + Deprecated Definition: IDOCs SHOULD NOT use definition 3 because + it mixes concepts in way that does not agree with common usage; a + security incident is commonly thought of as involving a + realization of a threat (see: threat action), not just a threat. + + $ security intrusion + (I) A security event, or a combination of multiple security + events, that constitutes a security incident in which an intruder + gains, or attempts to gain, access to a system or system resource + without having authorization to do so. + + + +Shirey Informational [Page 270] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ security kernel + (I) "The hardware, firmware, and software elements of a trusted + computing base that implement the reference monitor concept. It + must mediate all accesses, be protected from modification, and be + verifiable as correct." [NCS04] (See: kernel, TCB.) + + Tutorial: A security kernel is an implementation of a reference + monitor for a given hardware base. [Huff] + + $ security label + (I) An item of meta-data that designates the value of one or more + security-relevant attributes (e.g., security level) of a system + resource. (See: [R1457]. Compare: security marking.) + + Deprecated usage: To avoid confusion, IDOCs SHOULD NOT use + "security label" for "security marking", or vice versa, even + though that is commonly done (including in some national and + international standards that should know better). + + Tutorial: Humans and automated security mechanisms use a security + label of a system resource to determine, according to applicable + security policy, how to control access to the resource (and they + affix appropriate, matching security markings to physical + instances of the resource). Security labels are most often used to + support data confidentiality policy, and sometimes used to support + data integrity policy. + + As explained in [R1457], the form that is taken by security labels + of a protocol's packets varies depending on the OSIRM layer in + which the protocol operates. Like meta-data generally, a security + label of a data packet may be either explicit (e.g., IPSO) or + implicit (e.g., Alice treats all messages received from Bob as + being labeled "Not For Public Release"). In a connectionless + protocol, every packet might have an explicit label; but in a + connection-oriented protocol, all packets might have the same + implicit label that is determined at the time the connection is + established. + + Both classified and unclassified system resources may require a + security label. (See: FOUO.) + + $ security level + (I) The combination of a hierarchical classification level and a + set of non-hierarchical category designations that represents how + sensitive a specified type or item of information is. (See: + dominate, lattice model. Compare: classification level.) + + + + + +Shirey Informational [Page 271] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Usage: IDOCs that use this term SHOULD state a definition for it. + The term is usually understood to involve sensitivity to + disclosure, but it also is used in many other ways and could + easily be misunderstood. + + $ Security Level field + (I) A 16-bit field that specifies a security level value in the + security option (option type 130) of version 4 IP's datagram + header format. + + Deprecated Abbreviation: IDOCs SHOULD NOT use the abbreviation "S + field", which is potentially ambiguous. + + $ security management infrastructure (SMI) + (I) System components and activities that support security policy + by monitoring and controlling security services and mechanisms, + distributing security information, and reporting security events. + + Tutorial: The associated functions are as follows [I7498-4]: + - Controlling (granting or restricting) access to system + resources: This includes verifying authorizations and + identities, controlling access to sensitive security data, and + modifying access priorities and procedures in the event of + attacks. + - Retrieving (gathering) and archiving (storing) security + information: This includes logging security events and + analyzing the log, monitoring and profiling usage, and + reporting security violations. + - Managing and controlling the encryption process: This includes + performing the functions of key management and reporting on key + management problems. (See: PKI.) + + $ security marking + (I) A physical marking that is bound to an instance of a system + resource and that represents a security label of the resource, + i.e., that names or designates the value of one or more security- + relevant attributes of the resource. (Compare: security label.) + + Tutorial: A security label may be represented by various + equivalent markings depending on the physical form taken by the + labeled resource. For example, a document could have a marking + composed of a bit pattern [FP188] when the document is stored + electronically as a file in a computer, and also a marking of + printed alphabetic characters when the document is in paper form. + + + + + + + +Shirey Informational [Page 272] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ security mechanism + (I) A method or process (or a device incorporating it) that can be + used in a system to implement a security service that is provided + by or within the system. (See: Tutorial under "security policy". + Compare: security doctrine.) + + Usage: Usually understood to refer primarily to components of + communication security, computer security, and emanation security. + + Examples: Authentication exchange, checksum, digital signature, + encryption, and traffic padding. + + $ security model + (I) A schematic description of a set of entities and relationships + by which a specified set of security services are provided by or + within a system. Example: Bell-LaPadula model, OSIRM. (See: + Tutorial under "security policy".) + + $ security parameters index (SPI) + 1. (I) /IPsec/ A 32-bit identifier used to distinguish among + security associations that terminate at the same destination (IP + address) and use the same security protocol (AH or ESP). Carried + in AH and ESP to enable the receiving system to determine under + which security association to process a received packet. + + 2. (I) /mobile IP/ A 32-bit index identifying a security + association from among the collection of associations that are + available between a pair of nodes, for application to mobile IP + protocol messages that the nodes exchange. + + $ security perimeter + (I) A physical or logical boundary that is defined for a domain or + enclave and within which a particular security policy or security + architecture applies. (See: insider, outsider.) + + $ security policy + 1. (I) A definite goal, course, or method of action to guide and + determine present and future decisions concerning security in a + system. [NCS03, R3198] (Compare: certificate policy.) + + 2a. (I) A set of policy rules (or principles) that direct how a + system (or an organization) provides security services to protect + sensitive and critical system resources. (See: identity-based + security policy, policy rule, rule-based security policy, rules of + behavior. Compare: security architecture, security doctrine, + security mechanism, security model, [R1281].) + + + + + +Shirey Informational [Page 273] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + 2b. (O) A set of rules to administer, manage, and control access + to network resources. [R3060, R3198] + + 2c. (O) /X.509/ A set of rules laid down by an authority to govern + the use and provision of security services and facilities. + + 2d. (O) /Common Criteria/ A set of rules that regulate how assets + are managed, protected, and distributed within a TOE. + + Tutorial: Ravi Sandhu suggests that security policy is one of four + layers of the security engineering process (as shown in the + following diagram). Each layer provides a different view of + security, ranging from what services are needed to how services + are implemented. + + What Security Services + Should Be Provided? +- - - - - - - - - - - - -+ + ^ +- - - - - - - - - - - -| Mission Functions View | + | | Security Policy |- - - - - - - - - - - - -+ + | +- - - - - - - - - - - -| Domain Practices View | + | | Security Model |- - - - - - - - - - - - -+ + | +- - - - - - - - - - - -| Enclave Services View | + | | Security Architecture |- - - - - - - - - - - - -+ + | +- - - - - - - - - - - -| Agent Mechanisms View | + | | Security Mechanism |- - - - - - - - - - - - -+ + v +- - - - - - - - - - - -| Platform Devices View | + How Are Security +- - - - - - - - - - - - -+ + Services Implemented? + + We suggest that each of Sandhu's four layers is a mapping between + two points of view that differ in their degree of abstraction, + according to the perspectives of various participants in system + design, development, and operation activities, as follows:. + - Mission functions view: The perspective of a user of system + resources. States time-phased protection needs for resources + and identifies sensitive and critical resources -- networks, + hosts, applications, and databases. Independent of rules and + practices used to achieve protection. + - Domain practices view: The perspective of an enterprise manager + who sets protection standards for resources. States rules and + practices for protection. Identifies domain members; i.e., + entities (users/providers) and resources (including data + objects). Independent of system topology. Not required to be + hierarchical. + - Enclave services view: The perspective of a system designer who + allocates security functions to major components. Assigns + security services to system topology structures and their + + + + +Shirey Informational [Page 274] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + contents. Independent of security mechanisms. Hierarchical + across all domains. + - Agent mechanisms view: The perspective of a system engineer who + specifies security mechanisms to implement security services. + Specifies mechanisms to be used by protocol, database, and + application engines. Independent of type and manufacture of + platforms and other physical devices. + - Platform devices view: The perspective of an as-built + description of the system in operation. Specifies exactly how + to build or assemble the system, and also specifies procedures + for operating the system. + + $ Security Policy Database (SPD) + (I) /IPsec/ In an IPsec implementation operating in a network + node, a database that contains parameters that specify policies + set by a user or administrator to determine what IPsec services, + if any, are to be provided to IP datagrams sent or received by the + node, and in what fashion they are provided. For each datagram, + the SPD specifies one of three choices: discard the datagram, + apply IPsec services (e.g., AH or ESP), or bypass IPsec. Separate + inbound and outbound SPDs are needed because of the directionality + of IPsec security associations. [R4301] (Compare: SAD.) + + $ Security Protocol 3 (SP3) + (O) A protocol [SDNS3] developed by SDNS to provide connectionless + data security at the top of OSIRM Layer 3. (Compare: IPsec, NLSP.) + + $ Security Protocol 4 (SP4) + (O) A protocol [SDNS4] developed by SDNS to provide either + connectionless or end-to-end connection-oriented data security at + the bottom of OSIRM Layer 4. (See: TLSP.) + + $ security-relevant event + (D) Synonym for "security event". + + Deprecated Term: IDOCs SHOULD NOT use this term; it is wordy. + + $ security-sensitive function + (D) Synonym for "security function". + + Deprecated Term: IDOCs SHOULD NOT use this term; it is wordy. + + $ security service + 1. (I) A processing or communication service that is provided by a + system to give a specific kind of protection to system resources. + (See: access control service, audit service, availability service, + data confidentiality service, data integrity service, data origin + + + + +Shirey Informational [Page 275] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + authentication service, non-repudiation service, peer entity + authentication service, system integrity service.) + + Tutorial: Security services implement security policies, and are + implemented by security mechanisms. + + 2. (O) "A service, provided by a layer of communicating open + systems, [that] ensures adequate security of the systems or the + data transfers." [I7498-2] + + $ security situation + (I) /ISAKMP/ The set of all security-relevant information (e.g., + network addresses, security classifications, manner of operation + such as normal or emergency) that is needed to decide the security + services that are required to protect the association that is + being negotiated. + + $ security target + (N) /Common Criteria/ A set of security requirements and + specifications to be used as the basis for evaluation of an + identified TOE. + + Tutorial: A security target (ST) is a statement of security claims + for a particular information technology security product or + system, and is the basis for agreement among all parties as to + what security the product or system offers. An ST parallels the + structure of a protection profile, but has additional elements + that include product-specific detailed information. An ST contains + a summary specification, which defines the specific measures taken + in the product or system to meet the security requirements. + + $ security token + (I) See: token. + + $ security violation + (I) An act or event that disobeys or otherwise breaches security + policy. (See: compromise, penetration, security incident.) + + $ seed + (I) A value that is an input to a pseudorandom number generator. + + $ selective-field confidentiality + (I) A data confidentiality service that preserves confidentiality + for one or more parts (i.e., fields) of each packet. (See: + selective-field integrity.) + + Tutorial: Data confidentiality service usually is applied to + entire SDUs, but some situations might require protection of only + + + +Shirey Informational [Page 276] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + part of each packet. For example, when Alice uses a debit card at + an automated teller machine (ATM), perhaps only her PIN is + enciphered for confidentiality when her transaction request is + transmitted from the ATM to her bank's computer. + + In any given operational situation, there could be many different + reasons for using selective field confidentiality. In the ATM + example, there are at least four possibilities: The service may + provide a fail-safe mode of operation, ensuring that the bank can + still process transactions (although with some risk) even when the + encryption system fails. It may make messages easier to work with + when doing system fault isolation. It may avoid problems with laws + that prevent shipping enciphered data across international + borders. It may improve efficiency by reducing processing load at + a central computer site. + + $ selective-field integrity + (I) A data integrity service that preserves integrity for one or + more parts (i.e., fields) of each packet. (See: selective-field + confidentiality.) + + Tutorial: Data integrity service may be implemented in a protocol + to protect the SDU part of packets, the PCI part, or both. + - SDU protection: When service is provided for SDUs, it usually + is applied to entire SDUs, but it might be applied only to + parts of SDUs in some situations. For example, an IPS + Application-Layer protocol might need protection of only part + of each packet, and this might enable faster processing. + - PCI protection: To prevent active wiretapping, it might be + desirable to apply data integrity service to the entire PCI, + but some PCI fields in some protocols need to be mutable in + transit. For example, the "Time to Live" field in IPv4 is + changed each time a packet passes through a router in the + Internet Layer. Thus, the value that the field will have when + the packet arrives at its destination is not predictable by the + sender and cannot be included in a checksum computed by the + sender. (See: Authentication Header.) + + $ self-signed certificate + (I) A public-key certificate for which the public key bound by the + certificate and the private key used to sign the certificate are + components of the same key pair, which belongs to the signer. + (Compare: root certificate.) + + Tutorial: In a self-signed X.509 public-key certificate, the + issuer's DN is the same as the subject's DN. + + + + + +Shirey Informational [Page 277] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ semantic security + (I) An attribute of an encryption algorithm that is a + formalization of the notion that the algorithm not only hides the + plain text but also reveals no partial information about the plain + text; i.e., whatever is computable about the plain text when given + the cipher text, is also computable without the cipher text. + (Compare: indistinguishability.) + + $ semiformal + (I) Expressed in a restricted syntax language with defined + semantics. [CCIB] (Compare: formal, informal.) + + $ sensitive + (I) A condition of a system resource such that the loss of some + specified property of that resource, such as confidentiality or + integrity, would adversely affect the interests or business of its + owner or user. (See: sensitive information. Compare: critical.) + + $ sensitive compartmented information (SCI) + (O) /U.S. Government/ Classified information concerning or derived + from intelligence sources, methods, or analytical processes, which + is required to be handled within formal control systems + established by the Director of Central Intelligence. [C4009] (See: + compartment, SAP, SCIF. Compare: collateral information.) + + $ sensitive compartmented information facility (SCIF) + (O) /U.S. Government/ "An accredited area, room, group of rooms, + building, or installation where SCI may be stored, used, + discussed, and/or processed." [C4009] (See: SCI. Compare: shielded + enclosure.) + + $ sensitive information + 1. (I) Information for which (a) disclosure, (b) alteration, or + (c) destruction or loss could adversely affect the interests or + business of its owner or user. (See: data confidentiality, data + integrity, sensitive. Compare: classified, critical.) + + 2. (O) /U.S. Government/ Information for which (a) loss, (b) + misuse, (c) unauthorized access, or (d) unauthorized modification + could adversely affect the national interest or the conduct of + federal programs, or the privacy to which individuals are entitled + under the Privacy Act of 1974, but that has not been specifically + authorized under criteria established by an Executive Order or an + Act of Congress to be kept classified in the interest of national + defense or foreign policy. + + Tutorial: Systems that are not U.S. national security systems, but + contain sensitive U.S. Federal Government information, must be + + + +Shirey Informational [Page 278] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + protected according to the Computer Security Act of 1987 (Public + Law 100-235). (See: national security.) + + $ sensitivity label + (D) Synonym for "classification label". + + Deprecated term: IDOCs SHOULD NOT use this term because the + definition of "sensitive" involves not only data confidentiality, + but also data integrity. + + $ sensitivity level + (D) Synonym for "classification level". + + Deprecated term: IDOCs SHOULD NOT use this term because the + definition of "sensitive" involves not only data confidentiality, + but also data integrity. + + $ separation of duties + (I) The practice of dividing the steps in a system process among + different individual entities (i.e., different users or different + roles) so as to prevent a single entity acting alone from being + able to subvert the process. Usage: a.k.a. "separation of + privilege". (See: administrative security, dual control.) + + $ serial number + See: certificate serial number. + + $ Serpent + (O) A symmetric, 128-bit block cipher designed by Ross Anderson, + Eli Biham, and Lars Knudsen as a candidate for the AES. + + $ server + (I) A system entity that provides a service in response to + requests from other system entities called clients. + + $ service data unit (SDU) + (N) See: secondary definition under "protocol data unit". + + $ session + 1a. (I) /computer usage/ A continuous period of time, usually + initiated by a login, during which a user accesses a computer + system. + + 1b. (I) /computer activity/ The set of transactions or other + computer activities that are performed by or for a user during a + period of computer usage. + + + + + +Shirey Informational [Page 279] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + 2. (I) /access control/ A temporary mapping of a principal to one + or more roles. (See: role-based access control.) + + Tutorial: A user establishes a session as a principal and + activates some subset of roles to which the principal has been + assigned. The authorizations available to the principal in the + session are the union of the permissions of all the roles + activated in the session. Each session is associated with a single + principal and, therefore, with a single user. A principal may have + multiple, concurrent sessions and may activate a different set of + roles in each session. + + 3. (I) /computer network/ A persistent but (normally) temporary + association between a user agent (typically a client) and a second + process (typically a server). The association may persist across + multiple exchanges of data, including multiple connections. + (Compare: security association.) + + $ session key + (I) In the context of symmetric encryption, a key that is + temporary or is used for a relatively short period of time. (See: + ephemeral, KDC, session. Compare: master key.) + + Tutorial: A session key is used for a defined period of + communication between two system entities or components, such as + for the duration of a single connection or transaction set; or the + key is used in an application that protects relatively large + amounts of data and, therefore, needs to be rekeyed frequently. + + $ SET(trademark) + (O) See: SET Secure Electronic Transaction(trademark). + + $ SET private extension + (O) One of the private extensions defined by SET for X.509 + certificates. Carries information about hashed root key, + certificate type, merchant data, cardholder certificate + requirements, encryption support for tunneling, or message support + for payment instructions. + + $ SET qualifier + (O) A certificate policy qualifier that provides information about + the location and content of a SET certificate policy. + + Tutorial: Besides the policies and qualifiers inherited from its + own certificate, each CA in the SET certification hierarchy may + add one qualifying statement to the root policy when the CA issues + a certificate. The additional qualifier is a certificate policy + for that CA. Each policy in a SET certificate may have these + + + +Shirey Informational [Page 280] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + qualifiers: (a) a URL where a copy of the policy statement may be + found; (b) an electronic mail address where a copy of the policy + statement may be found; (c) a hash result of the policy statement, + computed using the indicated algorithm; and (d) a statement + declaring any disclaimers associated with the issuing of the + certificate. + + $ SET Secure Electronic Transaction(trademark) or SET(trademark) + (N) A protocol developed jointly by MasterCard International and + Visa International and published as an open standard to provide + confidentiality of transaction information, payment integrity, and + authentication of transaction participants for payment card + transactions over unsecured networks, such as the Internet. [SET1] + (See: acquirer, brand, cardholder, dual signature, electronic + commerce, IOTP, issuer, merchant, payment gateway, third party.) + + Tutorial: This term and acronym are trademarks of SETCo. + MasterCard and Visa announced the SET standard on 1 February 1996. + + $ SETCo + (O) Abbreviation of "SET Secure Electronic Transaction LLC", + formed on 19 December 1997 by MasterCard and Visa for implementing + the SET Secure Electronic Transaction(trademark) standard. A later + memorandum of understanding added American Express and JCB Credit + Card Company as co-owners of SETCo. + + $ SHA, SHA-1, SHA-2 + (N) See: Secure Hash Algorithm. + + $ shared identity + (I) See: secondary definition under "identity". + + $ shared secret + (D) Synonym for "cryptographic key" or "password". + + Deprecated Usage: IDOCs that use this term SHOULD state a + definition for it because the term is used in many ways and could + easily be misunderstood. + + $ shielded enclosure + (O) "Room or container designed to attenuate electromagnetic + radiation, acoustic signals, or emanations." [C4009] (See: + emanation. Compare: SCIF.) + + $ short title + (O) "Identifying combination of letters and numbers assigned to + certain items of COMSEC material to facilitate handling, + accounting, and controlling." [C4009] (Compare: KMID, long title.) + + + +Shirey Informational [Page 281] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ shroud + (D) /verb/ To encrypt a private key, possibly in concert with a + policy that prevents the key from ever being available in + cleartext form beyond a certain, well-defined security perimeter. + [PKC12] (See: encrypt. Compare: seal, wrap.) + + Deprecated Term: IDOCs SHOULD NOT use this term as defined here; + the definition duplicates the meaning of other, standard terms. + Instead, use "encrypt" or other terminology that is specific with + regard to the mechanism being used. + + $ SHS + (N) See: Secure Hash Standard. + + $ sign + (I) Create a digital signature for a data object. (See: signer.) + + $ signal analysis + (I) Gaining indirect knowledge (inference) of communicated data by + monitoring and analyzing a signal that is emitted by a system and + that contains the data but is not intended to communicate the + data. (See: emanation. Compare: traffic analysis.) + + $ signal intelligence + (I) The science and practice of extracting information from + signals. (See: signal security.) + + $ signal security + (N) (I) The science and practice of protecting signals. (See: + cryptology, security.) + + Tutorial: The term "signal" denotes (a) communication in almost + any form and also (b) emanations for other purposes, such as + radar. Signal security is opposed by signal intelligence, and each + discipline includes opposed sub-disciplines as follows [Kahn]: + + Signal Security Signal Intelligence + ------------------------------ --------------------------------- + 1. Communication Security 1. Communication Intelligence + 1a. Cryptography 1a. Cryptanalysis + 1b. Traffic Security 1b. Traffic Analysis + 1c. Steganography 1c. Detection and Interception + 2. Electronic Security 2. Electronic Intelligence + 2a. Emission Security 2a. Electronic Reconnaissance + 2b. Counter-Countermeasures 2b. Countermeasures + ------------------------------ --------------------------------- + + + + + +Shirey Informational [Page 282] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ signature + (O) A symbol or process adopted or executed by a system entity + with present intention to declare that a data object is genuine. + (See: digital signature, electronic signature.) + + $ signature certificate + (I) A public-key certificate that contains a public key that is + intended to be used for verifying digital signatures, rather than + for encrypting data or performing other cryptographic functions. + + Tutorial: A v3 X.509 public-key certificate may have a "keyUsage" + extension that indicates the purpose for which the certified + public key is intended. (See: certificate profile.) + + $ signed receipt + (I) An S/MIME service [R2634] that (a) provides, to the originator + of a message, proof of delivery of the message and (b) enables the + originator to demonstrate to a third party that the recipient was + able to verify the signature of the original message. + + Tutorial: The receipt is bound to the original message by a + signature; consequently, the service may be requested only for a + message that is signed. The receipt sender may optionally also + encrypt the receipt to provide confidentiality between the receipt + sender and the receipt recipient. + + $ signer + (N) A human being or organization entity that uses a private key + to sign (i.e., create a digital signature on) a data object. [DSG] + + $ SILS + (N) See: Standards for Interoperable LAN/MAN Security. + + $ simple authentication + 1. (I) An authentication process that uses a password as the + information needed to verify an identity claimed for an entity. + (Compare: strong authentication.) + + 2. (O) "Authentication by means of simple password arrangements." + [X509] + + $ Simple Authentication and Security Layer (SASL) + (I) An Internet specification [R2222, R4422] for adding + authentication service to connection-based protocols. (Compare: + EAP, GSS-API.) + + + + + + +Shirey Informational [Page 283] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Tutorial: To use SASL, a protocol includes a command for + authenticating a user to a server and for optionally negotiating + protection of subsequent protocol interactions. The command names + a registered security mechanism. SASL mechanisms include Kerberos, + GSS-API, S/KEY, and others. Some protocols that use SASL are IMAP4 + and POP3. + + $ Simple Key Management for Internet Protocols (SKIP) + (I) A key-distribution protocol that uses hybrid encryption to + convey session keys that are used to encrypt data in IP packets. + (See: SKIP reference in [R2356].) + + Tutorial: SKIP was designed by Ashar Aziz and Whitfield Diffie at + Sun Microsystems and proposed as the standard key management + protocol for IPsec, but IKE was chosen instead. Although IKE is + mandatory for an IPsec implementation, the use of SKIP is not + excluded. + + SKIP uses the Diffie-Hellman-Merkle algorithm (or could use + another key-agreement algorithm) to generate a key-encrypting key + for use between two entities. A session key is used with a + symmetric algorithm to encrypt data in one or more IP packets that + are to be sent from one entity to the other. A symmetric KEK is + established and used to encrypt the session key, and the encrypted + session key is placed in a SKIP header that is added to each IP + packet that is encrypted with that session key. + + $ Simple Mail Transfer Protocol (SMTP) + (I) A TCP-based, Application-Layer, Internet Standard protocol + (RFC 821) for moving electronic mail messages from one computer to + another. + + $ Simple Network Management Protocol (SNMP) + (I) A (usually) UDP-based, Application-Layer, Internet Standard + protocol (RFCs 3410-3418) for conveying management information + between system components that act as managers and agents. + + $ Simple Public Key Infrastructure (SPKI) + (I) A set of experimental concepts (RFCs 2692, 2693) that were + proposed as alternatives to the concepts standardized in PKIX. + + $ simple security property + (N) /formal model/ Property of a system whereby a subject has read + access to an object only if the clearance of the subject dominates + the classification of the object. See: Bell-LaPadula model. + + + + + + +Shirey Informational [Page 284] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ single sign-on + 1. (I) An authentication subsystem that enables a user to access + multiple, connected system components (such as separate hosts on a + network) after a single login at only one of the components. (See: + Kerberos.) + + 2. (O) /Liberty Alliance/ A security subsystem that enables a user + identity to be authenticated at an identity provider -- i.e., at a + service that authenticates and asserts the user's identity -- and + then have that authentication be honored by other service + providers. + + Tutorial: A single sign-on subsystem typically requires a user to + log in once at the beginning of a session, and then during the + session transparently grants access by the user to multiple, + separately protected hosts, applications, or other system + resources, without further login action by the user (unless, of + course, the user logs out). Such a subsystem has the advantages of + being user friendly and enabling authentication to be managed + consistently across an entire enterprise. Such a subsystem also + has the disadvantage of requiring all the accessed components to + depend on the security of the same authentication information. + + $ singular identity + (I) See: secondary definition under "identity". + + $ site + (I) A facility -- i.e., a physical space, room, or building + together with its physical, personnel, administrative, and other + safeguards -- in which system functions are performed. (See: + node.) + + $ situation + (I) See: security situation. + + $ SKEME + (I) A key-distribution protocol from which features were adapted + for IKE. [SKEME] + + $ SKIP + (I) See: Simple Key Management for Internet Protocols. + + $ SKIPJACK + (N) A type 2, 64-bit block cipher [SKIP, R2773] with a key size of + 80 bits. (See: CAPSTONE, CLIPPER, FORTEZZA, Key Exchange + Algorithm.) + + + + + +Shirey Informational [Page 285] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Tutorial: SKIPJACK was developed by NSA and formerly classified at + the U.S. DoD "Secret" level. On 23 June 1998, NSA announced that + SKIPJACK had been declassified. + + $ slot + (O) /MISSI/ One of the FORTEZZA PC card storage areas that are + each able to hold an X.509 certificate plus other data, including + the private key that is associated with a public-key certificate. + + $ smart card + (I) A credit-card sized device containing one or more integrated + circuit chips that perform the functions of a computer's central + processor, memory, and input/output interface. (See: PC card, + smart token.) + + Usage: Sometimes this term is used rather strictly to mean a card + that closely conforms to the dimensions and appearance of the kind + of plastic credit card issued by banks and merchants. At other + times, the term is used loosely to include cards that are larger + than credit cards, especially cards that are thicker, such as PC + cards. + + $ smart token + (I) A device that conforms to the definition of "smart card" + except that rather than having the standard dimensions of a credit + card, the token is packaged in some other form, such as a military + dog tag or a door key. (See: smart card, cryptographic token.) + + $ SMI + (I) See: security management infrastructure. + + $ SMTP + (I) See: Simple Mail Transfer Protocol. + + $ smurf attack + (D) /slang/ A denial-of-service attack that uses IP broadcast + addressing to send ICMP ping packets with the intent of flooding a + system. (See: fraggle attack, ICMP flood.) + + Deprecated Term: It is likely that other cultures use different + metaphors for this concept. Therefore, to avoid international + misunderstanding, IDOCs SHOULD NOT use this term. + + Derivation: The Smurfs are a fictional race of small, blue + creatures that were created by a cartoonist. Perhaps the inventor + of this attack thought that a swarm of ping packets resembled a + gang of smurfs. (See: Deprecated Usage under "Green Book".) + + + + +Shirey Informational [Page 286] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Tutorial: The attacker sends ICMP echo request ("ping") packets + that appear to originate not from the attacker's own IP address, + but from the address of the host or router that is the target of + the attack. Each packet is addressed to an IP broadcast address, + e.g., to all IP addresses in a given network. Thus, each echo + request that is sent by the attacker results in many echo + responses being sent to the target address. This attack can + disrupt service at a particular host, at the hosts that depend on + a particular router, or in an entire network. + + $ sneaker net + (D) /slang/ A process that transfers data between systems only + manually, under human control; i.e., a data transfer process that + involves an air gap. + + Deprecated Term: It is likely that other cultures use different + metaphors for this concept. Therefore, to avoid international + misunderstanding, IDOCs SHOULD NOT use this term. + + $ Snefru + (N) A public-domain, cryptographic hash function (a.k.a. "The + Xerox Secure Hash Function") designed by Ralph C. Merkle at Xerox + Corporation. Snefru can produce either a 128-bit or 256-bit output + (i.e., hash result). [Schn] (See: Khafre, Khufu.) + + $ sniffing + (D) /slang/ Synonym for "passive wiretapping"; most often refers + to capturing and examining the data packets carried on a LAN. + (See: password sniffing.) + + Deprecated Term: IDOCs SHOULD NOT use this term; it unnecessarily + duplicates the meaning of a term that is better established. (See: + Deprecated Usage under "Green Book". + + $ SNMP + (I) See: Simple Network Management Protocol. + + $ social engineering + (D) Euphemism for non-technical or low-technology methods, often + involving trickery or fraud, that are used to attack information + systems. Example: phishing. + + Deprecated Term: IDOCs SHOULD NOT use this term; it is too vague. + Instead, use a term that is specific with regard to the means of + attack, e.g., blackmail, bribery, coercion, impersonation, + intimidation, lying, or theft. + + + + + +Shirey Informational [Page 287] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ SOCKS + (I) An Internet protocol [R1928] that provides a generalized proxy + server that enables client-server applications (e.g., TELNET, FTP, + or HTTP; running over either TCP or UDP) to use the services of a + firewall. + + Tutorial: SOCKS is layered under the IPS Application Layer and + above the Transport Layer. When a client inside a firewall wishes + to establish a connection to an object that is reachable only + through the firewall, it uses TCP to connect to the SOCKS server, + negotiates with the server for the authentication method to be + used, authenticates with the chosen method, and then sends a relay + request. The SOCKS server evaluates the request, typically based + on source and destination addresses, and either establishes the + appropriate connection or denies it. + + $ soft TEMPEST + (O) The use of software techniques to reduce the radio frequency + information leakage from computer displays and keyboards. [Kuhn] + (See: TEMPEST.) + + $ soft token + (D) A data object that is used to control access or authenticate + authorization. (See: token.) + + Deprecated Term: IDOCs SHOULD NOT use this term as defined here; + the definition duplicates the meaning of other, standard terms. + Instead, use "attribute certificate" or another term that is + specific with regard to the mechanism being used. + + $ software + (I) Computer programs (which are stored in and executed by + computer hardware) and associated data (which also is stored in + the hardware) that may be dynamically written or modified during + execution. (Compare: firmware.) + + $ software error + (I) /threat action/ See: secondary definitions under "corruption", + "exposure", and "incapacitation". + + $ SORA + (O) See: SSO-PIN ORA. + + $ source authentication + (D) Synonym for "data origin authentication" or "peer entity + authentication". (See: data origin authentication, peer entity + authentication). + + + + +Shirey Informational [Page 288] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Deprecated Term: IDOCs SHOULD NOT use this term because it is + ambiguous and, in either meaning, duplicates the meaning of + internationally standardized terms. If the intent is to + authenticate the original creator or packager of data received, + then use "data origin authentication". If the intent is to + authenticate the identity of the sender of data in the current + instance, then use "peer entity authentication". + + $ source integrity + (I) The property that data is trustworthy (i.e., worthy of + reliance or trust), based on the trustworthiness of its sources + and the trustworthiness of any procedures used for handling data + in the system. Usage: a.k.a. Biba integrity. (See: integrity. + Compare: correctness integrity, data integrity.) + + Tutorial: For this kind of integrity, there are formal models of + unauthorized modification (see: Biba model) that logically + complement the more familiar models of unauthorized disclosure + (see: Bell-LaPadula model). In these models, objects are labeled + to indicate the credibility of the data they contain, and there + are rules for access control that depend on the labels. + + $ SP3 + (O) See: Security Protocol 3. + + $ SP4 + (O) See: Security Protocol 4. + + $ spam + 1a. (I) /slang verb/ To indiscriminately send unsolicited, + unwanted, irrelevant, or inappropriate messages, especially + commercial advertising in mass quantities. + + 1b. (I) /slang noun/ Electronic "junk mail". [R2635] + + Deprecated Usage: IDOCs SHOULD NOT use this term in uppercase + letters, because SPAM(trademark) is a trademark of Hormel Foods + Corporation. Hormel says, "We do not object to use of this slang + term [spam] to describe [unsolicited advertising email], although + we do object to the use of our product image in association with + that term. Also, if the term is to be used, it SHOULD be used in + all lower-case letters to distinguish it from our trademark SPAM, + which SHOULD be used with all uppercase letters." (See: metadata.) + + Tutorial: In sufficient volume, spam can cause denial of service. + (See: flooding.) According to Hormel, the term was adopted as a + result of a Monty Python skit in which a group of Vikings sang a + chorus of 'SPAM, SPAM, SPAM ...' in an increasing crescendo, + + + +Shirey Informational [Page 289] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + drowning out other conversation. This lyric became a metaphor for + the unsolicited advertising messages that threaten to overwhelm + other discourse on the Internet. + + $ SPD + (I) See: Security Policy Database. + + $ special access program (SAP) + (O) /U.S. Government/ "Sensitive program, [that is] approved in + writing by a head of agency with [i.e., who has] original top + secret classification authority, [and] that imposes need-to-know + and access controls beyond those normally provided for access to + Confidential, Secret, or Top Secret information. The level of + controls is based on the criticality of the program and the + assessed hostile intelligence threat. The program may be an + acquisition program, an intelligence program, or an operations and + support program." [C4009] (See: formal access approval, SCI. + Compare: collateral information.) + + $ SPI + (I) See: Security Parameters Index. + + $ SPKI + (I) See: Simple Public Key Infrastructure. + + $ split key + (I) A cryptographic key that is generated and distributed as two + or more separate data items that individually convey no knowledge + of the whole key that results from combining the items. (See: dual + control, split knowledge.) + + $ split knowledge + 1. (I) A security technique in which two or more entities + separately hold data items that individually do not convey + knowledge of the information that results from combining the + items. (See: dual control, split key.) + + 2. (O) "A condition under which two or more entities separately + have key components [that] individually convey no knowledge of the + plaintext key [that] will be produced when the key components are + combined in the cryptographic module." [FP140] + + $ spoof + (I) /threat action/ See: secondary definition under "masquerade". + + $ spoofing attack + (I) Synonym for "masquerade attack". + + + + +Shirey Informational [Page 290] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ spread spectrum + (N) A TRANSEC technique that transmits a signal in a bandwidth + much greater than the transmitted information needs. [F1037] + Example: frequency hopping. + + Tutorial: Usually uses a sequential, noise-like signal structure + to spread the normally narrowband information signal over a + relatively wide band of frequencies. The receiver correlates the + signals to retrieve the original information signal. This + technique decreases potential interference to other receivers, + while achieving data confidentiality and increasing immunity of + spread spectrum receivers to noise and interference. + + $ spyware + (D) /slang/ Software that an intruder has installed + surreptitiously on a networked computer to gather data from that + computer and send it through the network to the intruder or some + other interested party. (See: malicious logic, Trojan horse.) + + Deprecated Usage: IDOCs that use this term SHOULD state a + definition for it because the term is used in many ways and could + easily be misunderstood. + + Tutorial: Some examples of the types of data that might be + gathered by spyware are application files, passwords, email + addresses, usage histories, and keystrokes. Some examples of + motivations for gathering the data are blackmail, financial fraud, + identity theft, industrial espionage, market research, and + voyeurism. + + $ SSH(trademark) + (N) See: Secure Shell(trademark). + + $ SSL + (I) See: Secure Sockets Layer. + + $ SSO + (I) See: system security officer. + + $ SSO PIN + (O) /MISSI/ One of two PINs that control access to the functions + and stored data of a FORTEZZA PC card. Knowledge of the SSO PIN + enables a card user to perform the FORTEZZA functions intended for + use by an end user and also the functions intended for use by a + MISSI CA. (See: user PIN.) + + + + + + +Shirey Informational [Page 291] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ SSO-PIN ORA (SORA) + (O) /MISSI/ A MISSI organizational RA that operates in a mode in + which the ORA performs all card management functions and, + therefore, requires knowledge of the SSO PIN for FORTEZZA PC cards + issued to end users. + + $ Standards for Interoperable LAN/MAN Security (SILS) + 1. (N) The IEEE 802.10 standards committee. (See: [FP191].) + + 2. (N) A set of IEEE standards, which has eight parts: (a) Model, + including security management, (b) Secure Data Exchange protocol, + (c) Key Management, (d) [has been incorporated in (a)], (e) SDE + Over Ethernet 2.0, (f) SDE Sublayer Management, (g) SDE Security + Labels, and (h) SDE PICS Conformance. Parts b, e, f, g, and h are + incorporated in IEEE Standard 802.10-1998. + + $ star property + (N) See: *-property. + + $ Star Trek attack + (D) /slang/ An attack that penetrates your system where no attack + has ever gone before. + + Deprecated Usage: IDOCs SHOULD NOT use this term; it is a joke for + Trekkies. (See: Deprecated Usage under "Green Book".) + + $ static + (I) /adjective/ Refers to a cryptographic key or other parameter + that is relatively long-lived. (Compare: ephemeral.) + + $ steganography + (I) Methods of hiding the existence of a message or other data. + This is different than cryptography, which hides the meaning of a + message but does not hide the message itself. Examples: For + classic, physical methods, see [Kahn]; for modern, digital + methods, see [John]. (See: cryptology. Compare: concealment + system, digital watermarking.) + + $ storage channel + (I) See: covert storage channel. + + $ storage key + (I) A cryptographic key used by a device for protecting + information that is being maintained in the device, as opposed to + protecting information that is being transmitted between devices. + (See: cryptographic token, token copy. Compare: traffic key.) + + + + + +Shirey Informational [Page 292] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ stream cipher + (I) An encryption algorithm that breaks plain text into a stream + of successive elements (usually, bits) and encrypts the n-th + plaintext element with the n-th element of a parallel key stream, + thus converting the plaintext stream into a ciphertext stream. + [Schn] (See: block cipher.) + + $ stream integrity service + (I) A data integrity service that preserves integrity for a + sequence of data packets, including both (a) bit-by-bit datagram + integrity of each individual packet in the set and (b) packet-by- + packet sequential integrity of the set as a whole. (See: data + integrity. Compare: datagram integrity service.) + + Tutorial: Some internetwork applications need only datagram + integrity, but others require that an entire stream of packets be + protected against insertion, reordering, deletion, and delay: + - "Insertion": The destination receives an additional packet that + was not sent by the source. + - "Reordering": The destination receives packets in a different + order than that in which they were sent by the source. + - "Deletion": A packet sent by the source is not ever delivered + to the intended destination. + - "Delay": A packet is detained for some period of time at a + relay, thus hampering and postponing the packet's normal timely + delivery from source to destination. + + $ strength + 1. (I) /cryptography/ A cryptographic mechanism's level of + resistance to attacks [R3766]. (See: entropy, strong, work + factor.) + + 2. (N) /Common Criteria/ "Strength of function" is a + "qualification of a TOE security function expressing the minimum + efforts assumed necessary to defeat its expected security behavior + by directly attacking its underlying security mechanisms": (See: + strong.) + - Basic: "A level of the TOE strength of function where analysis + shows that the function provides adequate protection against + casual breach of TOE security by attackers possessing a low + attack potential." + - Medium: "... against straightforward or intentional breach ... + by attackers possessing a moderate attack potential." + - High: "... against deliberately planned or organized breach ... + by attackers possessing a high attack potential." + + + + + + +Shirey Informational [Page 293] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ strong + 1. (I) /cryptography/ Used to describe a cryptographic algorithm + that would require a large amount of computational power to defeat + it. (See: strength, work factor, weak key.) + + 2. (I) /COMPUSEC/ Used to describe a security mechanism that would + be difficult to defeat. (See: strength, work factor.) + + $ strong authentication + 1. (I) An authentication process that uses a cryptographic + security mechanism -- particularly public-key certificates -- to + verify the identity claimed for an entity. (Compare: simple + authentication.) + + 2. (O) "Authentication by means of cryptographically derived + credentials." [X509] + + $ subject + 1a. (I) A process in a computer system that represents a principal + and that executes with the privileges that have been granted to + that principal. (Compare: principal, user.) + + 1b. (I) /formal model/ A system entity that causes information to + flow among objects or changes the system state; technically, a + process-domain pair. A subject may itself be an object relative to + some other subject; thus, the set of subjects in a system is a + subset of the set of objects. (See: Bell-LaPadula model, object.) + + 2. (I) /digital certificate/ The name (of a system entity) that is + bound to the data items in a digital certificate; e.g., a DN that + is bound to a key in a public-key certificate. (See: X.509.) + + $ subject CA + (D) The CA that is the subject of a cross-certificate issued by + another CA. [X509] (See: cross-certification.) + + Deprecated Term: IDOCs SHOULD NOT use this term because it is not + widely known and could be misunderstood. Instead, say "the CA that + is the subject of the cross-certificate". + + $ subnetwork + (N) An OSI term for a system of packet relays and connecting links + that implement OSIRM layer 2 or 3 to provide a communication + service that interconnects attached end systems. Usually, the + relays are all of the same type (e.g., X.25 packet switches, or + interface units in an IEEE 802.3 LAN). (See: gateway, internet, + router.) + + + + +Shirey Informational [Page 294] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ subordinate CA (SCA) + 1. (I) A CA whose public-key certificate is issued by another + (superior) CA. (See: certification hierarchy. Compare: cross- + certification.) + + 2. (O) /MISSI/ The fourth-highest (i.e., bottom) level of a MISSI + certification hierarchy; a MISSI CA whose public-key certificate + is signed by a MISSI CA rather than by a MISSI PCA. A MISSI SCA is + the administrative authority for a subunit of an organization, + established when it is desirable to organizationally distribute or + decentralize the CA service. The term refers both to that + authoritative office or role, and to the person who fills that + office. A MISSI SCA registers end users and issues their + certificates and may also register ORAs, but may not register + other CAs. An SCA periodically issues a CRL. + + $ subordinate DN + (I) An X.500 DN is subordinate to another X.500 DN if it begins + with a set of attributes that is the same as the entire second DN + except for the terminal attribute of the second DN (which is + usually the name of a CA). For example, the DN <C=FooLand, O=Gov, + OU=Treasurer, CN=DukePinchpenny> is subordinate to the DN + <C=FooLand, O=Gov, CN=KingFooCA>. + + $ subscriber + (I) /PKI/ A user that is registered in a PKI and, therefore, can + be named in the "subject" field of a certificate issued by a CA in + that PKI. (See: registration, user.) + + Usage: This term is needed to distinguish registered users from + two other kinds of PKI users: + - Users that access the PKI but are not identified to it: For + example, a relying party may access a PKI repository to obtain + the certificate of some other party. (See: access.) + - Users that do not access the PKI: For example, a relying party + (see: certificate user) may use a digital certificate that was + obtained from a database that is not part of the PKI that + issued the certificate. + + $ substitution + 1. (I) /cryptography/ A method of encryption in which elements of + the plain text retain their sequential position but are replaced + by elements of cipher text. (Compare: transposition.) + + 2. (I) /threat action/ See: secondary definition under + "falsification". + + + + + +Shirey Informational [Page 295] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ subsystem + (I) A collection of related system components that together + perform a system function or deliver a system service. + + $ superencryption + (I) An encryption operation for which the plaintext input to be + transformed is the ciphertext output of a previous encryption + operation. (Compare: hybrid encryption.) + + $ superuser + (I) /UNIX/ Synonym for "root". + + $ survivability + (I) The ability of a system to remain in operation or existence + despite adverse conditions, including natural occurrences, + accidental actions, and attacks. (Compare: availability, + reliability.) + + $ swIPe + (I) An encryption protocol for IP that provides confidentiality, + integrity, and authentication and can be used for both end-to-end + and intermediate-hop security. [Ioan] (Compare: IPsec.) + + Tutorial: The swIPe protocol is an IP predecessor that is + concerned only with encryption mechanisms; policy and key + management are handled outside the protocol. + + $ syllabary + (N) /encryption/ A list of individual letters, combinations of + letters, or syllables, with their equivalent code groups, used for + spelling out proper names or other unusual words that are not + present in the basic vocabulary (i.e., are not in the codebook) of + a code used for encryption. + + $ symmetric cryptography + (I) A branch of cryptography in which the algorithms use the same + key for both of two counterpart cryptographic operations (e.g., + encryption and decryption). (See: asymmetric cryptography. + Compare: secret-key cryptography.) + + Tutorial: Symmetric cryptography has been used for thousands of + years [Kahn]. A modern example is AES. + + Symmetric cryptography has a disadvantage compared to asymmetric + cryptography with regard to key distribution. For example, when + Alice wants to ensure confidentiality for data she sends to Bob, + she encrypts the data with a key, and Bob uses the same key to + decrypt. However, keeping the shared key secret entails both cost + + + +Shirey Informational [Page 296] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + and risk when the key is distributed to both Alice and Bob. (See: + key distribution, key management.) + + $ symmetric key + (I) A cryptographic key that is used in a symmetric cryptographic + algorithm. (See: symmetric cryptography.) + + $ SYN flood + (I) A denial-of-service attack that sends a large number of TCP + SYN (synchronize) packets to a host with the intent of disrupting + the operation of that host. (See: blind attack, flooding.) + + Tutorial: This attack seeks to exploit a vulnerability in the TCP + specification or in a TCP implementation. Normally, two hosts use + a three-way exchange of packets to establish a TCP connection: (a) + host 1 requests a connection by sending a SYN packet to host 2; + (b) host 2 replies by sending a SYN-ACK (acknowledgement) packet + to host 1; and (c) host 1 completes the connection by sending an + ACK packet to host 2. To attack host 2, host 1 can send a series + of TCP SYNs, each with a different phony source address. ([R2827] + discusses how to use packet filtering to prevent such attacks from + being launched from behind an Internet service provider's + aggregation point.) Host 2 treats each SYN as a request from a + separate host, replies to each with a SYN-ACK, and waits to + receive the matching ACKs. (The attacker can use random or + unreachable sources addresses in the SYN packets, or can use + source addresses that belong to third parties, that then become + secondary victims.) + + For each SYN-ACK that is sent, the TCP process in host 2 needs + some memory space to store state information while waiting for the + matching ACK to be returned. If the matching ACK never arrives at + host 2, a timer associated with the pending SYN-ACK will + eventually expire and release the space. But if host 1 (or a + cooperating group of hosts) can rapidly send many SYNs to host 2, + host 2 will need to store state information for many pending SYN- + ACKs and may run out of space. This can prevent host 2 from + responding to legitimate connection requests from other hosts or + even, if there are flaws in host 2's TCP implementation, crash + when the available space is exhausted. + + $ synchronization + (I) Any technique by which a receiving (decrypting) cryptographic + process attains an internal state that matches the transmitting + (encrypting) process, i.e., has the appropriate keying material to + process the cipher text and is correctly initialized to do so. + + + + + +Shirey Informational [Page 297] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ system + (I) Synonym for "information system". + + Usage: This is a generic definition, and is the one with which the + term is used in this Glossary. However, IDOCs that use the term, + especially IDOCs that are protocol specifications, SHOULD state a + more specific definition. Also, IDOCs that specify security + features, services, and assurances need to define which system + components and system resources are inside the applicable security + perimeter and which are outside. (See: security architecture.) + + $ system architecture + (N) The structure of system components, their relationships, and + the principles and guidelines governing their design and evolution + over time. [DoD10] (Compare: security architecture.) + + $ system component + 1. (I) A collection of system resources that (a) forms a physical + or logical part of the system, (b) has specified functions and + interfaces, and (c) is treated (e.g., by policies or + specifications) as existing independently of other parts of the + system. (See: subsystem.) + + 2. (O) /ITSEC/ An identifiable and self-contained part of a TOE. + + Usage: Component is a relative term because components may be + nested; i.e., one component of a system may be a part of another + component of that system. + + Tutorial: Components can be characterized as follows: + - A "physical component" has mass and takes up space. + - A "logical component" is an abstraction used to manage and + coordinate aspects of the physical environment, and typically + represents a set of states or capabilities of the system. + + $ system entity + (I) An active part of a system -- a person, a set of persons + (e.g., some kind of organization), an automated process, or a set + of processes (see: subsystem) -- that has a specific set of + capabilities. (Compare: subject, user.) + + $ system high + (I) The highest security level at which a system operates, or is + capable of operating, at a particular time or in a particular + environment. (See: system-high security mode.) + + + + + + +Shirey Informational [Page 298] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ system-high security mode + (I) A mode of system operation wherein all users having access to + the system possess all necessary authorizations (both security + clearance and formal access approval) for all data handled by the + system, but some users might not have need-to-know for all the + data. (See: /system operation/ under "mode", formal access + approval, protection level, security clearance.) + + Usage: Usually abbreviated as "system-high mode". This mode was + defined in U.S. DoD policy that applied to system accreditation, + but the term is widely used outside the Government. + + $ system integrity + 1. (I) An attribute or quality "that a system has when it can + perform its intended function in a unimpaired manner, free from + deliberate or inadvertent unauthorized manipulation." [C4009, + NCS04] (See: recovery, system integrity service.) + + 2. (D) "Quality of an [information system] reflecting the logical + correctness and reliability of the operating system; the logical + completeness of the hardware and software implementing the + protection mechanisms; and the consistency of the data structures + and occurrence of the stored data." [from an earlier version of + C4009] + + Deprecated Definition: IDOCs SHOULD NOT use definition 2 because + it mixes several concepts in a potentially misleading way. + Instead, IDOCs should use the term with definition 1 and, + depending on what is meant, couple the term with additional, more + specifically descriptive and informative terms, such as + "correctness", "reliability", and "data integrity". + + $ system integrity service + (I) A security service that protects system resources in a + verifiable manner against unauthorized or accidental change, loss, + or destruction. (See: system integrity.) + + $ system low + (I) The lowest security level supported by a system at a + particular time or in a particular environment. (Compare: system + high.) + + $ system resource + (I) Data contained in an information system; or a service provided + by a system; or a system capacity, such as processing power or + communication bandwidth; or an item of system equipment (i.e., + + + + + +Shirey Informational [Page 299] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + hardware, firmware, software, or documentation); or a facility + that houses system operations and equipment. (See: system + component.) + + $ system security officer (SSO) + (I) A person responsible for enforcement or administration of the + security policy that applies to a system. (Compare: manager, + operator.) + + $ system user + (I) A system entity that consumes a product or service provided by + the system, or that accesses and employs system resources to + produce a product or service of the system. (See: access, [R2504]. + Compare: authorized user, manager, operator, principal, privileged + user, subject, subscriber, system entity, unauthorized user.) + + Usage: IDOCs that use this term SHOULD state a definition for it + because the term is used in many ways and could easily be + misunderstood: + - This term usually refers to an entity that has been authorized + to access the system, but the term sometimes is used without + regard for whether access is authorized. + - This term usually refers to a living human being acting either + personally or in an organizational role. However, the term also + may refer to an automated process in the form of hardware, + software, or firmware; to a set of persons; or to a set of + processes. + - IDOCs SHOULD NOT use the term to refer to a mixed set + containing both persons and processes. This exclusion is + intended to prevent situations that might cause a security + policy to be interpreted in two different and conflicting ways. + + A system user can be characterized as direct or indirect: + - "Passive user": A system entity that is (a) outside the + system's security perimeter *and* (b) can receive output from + the system but cannot provide input or otherwise interact with + the system. + - "Active user": A system entity that is (a) inside the system's + security perimeter *or* (b) can provide input or otherwise + interact with the system. + + $ TACACS + (I) See: Terminal Access Controller (TAC) Access Control System. + + $ TACACS+ + (I) A TCP-based protocol that improves on TACACS by separating the + functions of authentication, authorization, and accounting and by + encrypting all traffic between the network access server and + + + +Shirey Informational [Page 300] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + authentication server. TACACS+ is extensible to allow any + authentication mechanism to be used with TACACS+ clients. + + $ tamper + (I) Make an unauthorized modification in a system that alters the + system's functioning in a way that degrades the security services + that the system was intended to provide. (See: QUADRANT. Compare: + secondary definitions under "corruption" and "misuse".) + + $ tamper-evident + (I) A characteristic of a system component that provides evidence + that an attack has been attempted on that component or system. + + Usage: Usually involves physical evidence. (See: tamper.) + + $ tamper-resistant + (I) A characteristic of a system component that provides passive + protection against an attack. (See: tamper.) + + Usage: Usually involves physical means of protection. + + $ tampering + (I) /threat action/ See: secondary definitions under "corruption" + and "misuse". + + $ target of evaluation (TOE) + (N) /Common Criteria/ An information technology product or system + that is the subject of a security evaluation, together with the + product's associated administrator and user documentation. + (Compare: protection profile.) + + Tutorial: The security characteristics of the target of evaluation + (TOE) are described in specific terms by a corresponding security + target, or in more general terms by a protection profile. In + Common Criteria philosophy, it is important that a TOE be + evaluated against the specific set of criteria expressed in the + target. This evaluation consists of rigorous analysis and testing + performed by an accredited, independent laboratory. The scope of a + TOE evaluation is set by the EAL and other requirements specified + in the target. Part of this process is an evaluation of the target + itself, to ensure that it is correct, complete, and internally + consistent and can be used as the baseline for the TOE evaluation. + + $ TCB + (N) See: trusted computing base. + + $ TCC field + (I) See: Transmission Control Code field. + + + +Shirey Informational [Page 301] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ TCG + (N) See: Trusted Computing Group. + + $ TCP + (I) See: Transmission Control Protocol. + + $ TCP/IP + (I) Synonym for "Internet Protocol Suite". + + $ TCSEC + (N) See: Trusted Computer System Evaluation Criteria. (Compare: + TSEC.) + + $ TDEA + (I) See: Triple Data Encryption Algorithm. + + $ teardrop attack + (D) /slang/ A denial-of-service attack that sends improperly + formed IP packet fragments with the intent of causing the + destination system to fail. + + Deprecated Term: IDOCs that use this term SHOULD state a + definition for it because the term is often used imprecisely and + could easily be misunderstood. (See: Deprecated Usage under "Green + Book".) + + $ technical non-repudiation + (I) See: (secondary definition under) non-repudiation. + + $ technical security + (I) Security mechanisms and procedures that are implemented in and + executed by computer hardware, firmware, or software to provide + automated protection for a system. (See: security architecture. + Compare: administrative security.) + + $ Telecommunications Security Word System (TSEC) + (O) /U.S. Government/ A terminology for designating + telecommunication security equipment. (Compare: TCSEC.) + + Tutorial: A TSEC designator has the following parts: + - Prefix "TSEC/" for items and systems, or suffix "/TSEC" for + assemblies. (Often omitted when the context is clear.) + - First letter, for function: "C" COMSEC equipment system, "G" + general purpose, "K" cryptographic, "H" crypto-ancillary, "M" + manufacturing, "N" noncryptographic, "S" special purpose. + - Second letter, for type or purpose: "G" key generation, "I" + data transmission, "L" literal conversion, "N" signal + conversion, "O" multipurpose, "P" materials production, "S" + + + +Shirey Informational [Page 302] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + special purpose, "T" testing or checking, "U" television, "W" + teletypewriter, "X" facsimile, "Y" speech. + - Optional third letter, used only in designations of assemblies, + for type or purpose: "A" advancing, "B" base or cabinet, "C" + combining, "D" drawer or panel, "E" strip or chassis, "F" frame + or rack, "G" key generator, "H" keyboard, "I" translator or + reader, "J" speech processing, "K" keying or permuting, "L" + repeater, "M" memory or storage, "O" observation, "P" power + supply or converter, "R" receiver, "S" synchronizing, "T" + transmitter, "U" printer, "V" removable COMSEC component, "W" + logic programmer/programming, "X" special purpose. + - Model number, usually two or three digits, assigned + sequentially within each letter combination (e.g., KG-34, KG- + 84). + - Optional suffix letter, used to designate a version. First + version has no letter, next version has "A" (e.g., KG-84, KG- + 84A), etc. + + $ TELNET + (I) A TCP-based, Application-Layer, Internet Standard protocol + (RFC 854) for remote login from one host to another. + + $ TEMPEST + 1. (N) Short name for technology and methods for protecting + against data compromise due to electromagnetic emanations from + electrical and electronic equipment. [Army, Russ] (See: + inspectable space, soft TEMPEST, TEMPEST zone. Compare: QUADRANT) + + 2. (O) /U.S. Government/ "Short name referring to investigation, + study, and control of compromising emanations from IS equipment." + [C4009] + + Deprecated Usage: IDOCs SHOULD NOT use this term as a synonym for + "electromagnetic emanations security"; instead, use EMSEC. Also, + the term is NOT an acronym for Transient Electromagnetic Pulse + Surveillance Technology. + + Tutorial: The U.S. Federal Government issues security policies + that (a) state specifications and standards for techniques to + reduce the strength of emanations from systems and reduce the + ability of unauthorized parties to receive and make use of + emanations and (b) state rules for applying those techniques. + Other nations presumably do the same. + + $ TEMPEST zone + (O) "Designated area [i.e., a physical volume] within a facility + where equipment with appropriate TEMPEST characteristics ... may + + + + +Shirey Informational [Page 303] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + be operated." [C4009] (See: emanation security, TEMPEST. Compare: + control zone, inspectable space.) + + Tutorial: The strength of an electromagnetic signal decreases in + proportion to the square of the distance between the source and + the receiver. Therefore, EMSEC for electromagnetic signals can be + achieved by a combination of (a) reducing the strength of + emanations to a defined level and (b) establishing around that + equipment an appropriately sized physical buffer zone from which + unauthorized entities are excluded. By making the zone large + enough, it is possible to limit the signal strength available to + entities outside the zone to a level lower than can be received + and read with known, state-of-the-art methods. Typically, the need + for and size of a TEMPEST zone established by a security policy + depends not only on the measured level of signal emitted by + equipment, but also on the perceived threat level in the + equipment's environment. + + $ Terminal Access Controller (TAC) Access Control System (TACACS) + (I) A UDP-based authentication and access control protocol [R1492] + in which a network access server receives an identifier and + password from a remote terminal and passes them to a separate + authentication server for verification. (See: TACACS+.) + + Tutorial: TACACS can provide service not only for network access + servers but also routers and other networked computing devices via + one or more centralized authentication servers. TACACS was + originally developed for ARPANET and has evolved for use in + commercial equipment. + + $ TESS + (I) See: The Exponential Encryption System. + + $ The Exponential Encryption System (TESS) + (I) A system of separate but cooperating cryptographic mechanisms + and functions for the secure authenticated exchange of + cryptographic keys, the generation of digital signatures, and the + distribution of public keys. TESS uses asymmetric cryptography, + based on discrete exponentiation, and a structure of self- + certified public keys. [R1824] + + $ theft + (I) /threat action/ See: secondary definitions under + "interception" and "misappropriation". + + $ threat + 1a. (I) A potential for violation of security, which exists when + there is an entity, circumstance, capability, action, or event + + + +Shirey Informational [Page 304] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + that could cause harm. (See: dangling threat, INFOCON level, + threat action, threat agent, threat consequence. Compare: attack, + vulnerability.) + + 1b. (N) Any circumstance or event with the potential to adversely + affect a system through unauthorized access, destruction, + disclosure, or modification of data, or denial of service. [C4009] + (See: sensitive information.) + + Usage: (a) Frequently misused with the meaning of either "threat + action" or "vulnerability". (b) In some contexts, "threat" is used + more narrowly to refer only to intelligent threats; for example, + see definition 2 below. (c) In some contexts, "threat" is used + more broadly to cover both definition 1 and other concepts, such + as in definition 3 below. + + Tutorial: A threat is a possible danger that might exploit a + vulnerability. Thus, a threat may be intentional or not: + - "Intentional threat": A possibility of an attack by an + intelligent entity (e.g., an individual cracker or a criminal + organization). + - "Accidental threat": A possibility of human error or omission, + unintended equipment malfunction, or natural disaster (e.g., + fire, flood, earthquake, windstorm, and other causes listed in + [FP031]). + + The Common Criteria characterizes a threat in terms of (a) a + threat agent, (b) a presumed method of attack, (c) any + vulnerabilities that are the foundation for the attack, and (d) + the system resource that is attacked. That characterization agrees + with the definitions in this Glossary (see: diagram under + "attack"). + + 2. (O) The technical and operational ability of a hostile entity + to detect, exploit, or subvert a friendly system and the + demonstrated, presumed, or inferred intent of that entity to + conduct such activity. + + Tutorial: To be likely to launch an attack, an adversary must have + (a) a motive to attack, (b) a method or technical ability to make + the attack, and (c) an opportunity to appropriately access the + targeted system. + + 3. (D) "An indication of an impending undesirable event." [Park] + + Deprecated Definition: IDOCs SHOULD NOT use this term with + definition 3 because the definition is ambiguous; the definition + was intended to include the following three meanings: + + + +Shirey Informational [Page 305] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + - "Potential threat": A possible security violation; i.e., the + same as definition 1. + - "Active threat": An expression of intent to violate security. + (Context usually distinguishes this meaning from the previous + one.) + - "Accomplished threat" or "actualized threat": That is, a threat + action. Deprecated Usage: IDOCs SHOULD NOT use the term + "threat" with this meaning; instead, use "threat action". + + $ threat action + (I) A realization of a threat, i.e., an occurrence in which system + security is assaulted as the result of either an accidental event + or an intentional act. (See: attack, threat, threat consequence.) + + Tutorial: A complete security architecture deals with both + intentional acts (i.e., attacks) and accidental events [FP031]. + (See: various kinds of threat actions defined under the four kinds + of "threat consequence".) + + $ threat agent + (I) A system entity that performs a threat action, or an event + that results in a threat action. + + $ threat analysis + (I) An analysis of the threat actions that might affect a system, + primarily emphasizing their probability of occurrence but also + considering their resulting threat consequences. Example: RFC + 3833. (Compare: risk analysis.) + + $ threat consequence + (I) A security violation that results from a threat action. + + Tutorial: The four basic types of threat consequence are + "unauthorized disclosure", "deception", "disruption", and + "usurpation". (See main Glossary entries of each of these four + terms for lists of the types of threat actions that can result in + these consequences.) + + $ thumbprint + 1. (I) A pattern of curves formed by the ridges on the tip of a + thumb. (See: biometric authentication, fingerprint.) + + 2. (D) Synonym for some type of "hash result". (See: biometric + authentication. Compare: fingerprint.) + + Deprecated Usage: IDOCs SHOULD NOT use this term with definition 2 + because that meaning mixes concepts in a potentially misleading + way. + + + +Shirey Informational [Page 306] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ ticket + (I) Synonym for "capability token". + + Tutorial: A ticket is usually granted by a centralized access + control server (ticket-granting agent) to authorize access to a + system resource for a limited time. Tickets can be implemented + with either symmetric cryptography (see: Kerberos) or asymmetric + cryptography (see: attribute certificate). + + $ tiger team + (O) A group of evaluators employed by a system's managers to + perform penetration tests on the system. + + Deprecated Usage: It is likely that other cultures use different + metaphors for this concept. Therefore, to avoid international + misunderstanding, IDOCs SHOULD NOT use this term. (See: Deprecated + Usage under "Green Book".) + + $ time stamp + 1. (I) /noun/ With respect to a data object, a label or marking in + which is recorded the time (time of day or other instant of + elapsed time) at which the label or marking was affixed to the + data object. (See: Time-Stamp Protocol.) + + 2. (O) /noun/ "With respect to a recorded network event, a data + field in which is recorded the time (time of day or other instant + of elapsed time) at which the event took place." [A1523] + + Tutorial: A time stamp can be used as evidence to prove that a + data object existed (or that an event occurred) at or before a + particular time. For example, a time stamp might be used to prove + that a digital signature based on a private key was created while + the corresponding public-key certificate was valid, i.e., before + the certificate either expired or was revoked. Establishing this + proof would enable the certificate to be used after its expiration + or revocation, to verify a signature that was created earlier. + This kind of proof is required as part of implementing PKI + services, such as non-repudiation service, and long-term security + services, such as audit. + + $ Time-Stamp Protocol + (I) An Internet protocol (RFC 3161) that specifies how a client + requests and receives a time stamp from a server for a data object + held by the client. + + Tutorial: The protocol describes the format of (a) a request sent + to a time-stamp authority and (b) the response that is returned + containing a time stamp. The authority creates the stamp by + + + +Shirey Informational [Page 307] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + concatenating (a) a hash value of the input data object with (b) a + UTC time value and other parameters (policy OID, serial number, + indication of time accuracy, nonce, DN of the authority, and + various extensions), and then signing that dataset with the + authority's private key as specified in CMS. Such an authority + typically would operate as a trusted third-party service, but + other operational models might be used. + + $ timing channel + (I) See: covert timing channel. + + $ TKEY + (I) A mnemonic referring to an Internet protocol (RFC 2930) for + establishing a shared secret key between a DNS resolver and a DNS + name server. (See: TSIG.) + + $ TLS + (I) See: Transport Layer Security. + + $ TLSP + (N) See: Transport Layer Security Protocol. + + $ TOE + (N) See: target of evaluation. + + $ token + 1. (I) /cryptography/ See: cryptographic token. (Compare: dongle.) + + 2. (I) /access control/ An object that is used to control access + and is passed between cooperating entities in a protocol that + synchronizes use of a shared resource. Usually, the entity that + currently holds the token has exclusive access to the resource. + (See: capability token.) + + Usage: This term is heavily overloaded in the computing + literature; therefore, IDOCs SHOULD NOT use this term with any + definition other than 1 or 2. + + 3a. (D) /authentication/ A data object or a physical device used + to verify an identity in an authentication process. + + 3b. (D) /U.S. Government/ Something that the claimant in an + authentication process (i.e., the entity that claims an identity) + possesses and controls, and uses to prove the claim during the + verification step of the process. [SP63] + + Deprecated usage: IDOCs SHOULD NOT use this term with definitions + 3a and 3b; instead, use more specifically descriptive and + + + +Shirey Informational [Page 308] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + informative terms such as "authentication information" or + "cryptographic token", depending on what is meant. + + NIST defines four types of claimant tokens for electronic + authentication in an information system [SP63]. IDOCs SHOULD NOT + use these four NIST terms; they mix concepts in potentially + confusing ways and duplicate the meaning of better-established + terms. These four terms can be avoided by using more specifically + descriptive terms as follows: + - NIST "hard token": A hardware device that contains a protected + cryptographic key. (This is a type of "cryptographic token", + and the key is a type of "authentication information".) + - NIST "one-time password device token": A personal hardware + device that generates one-time passwords. (One-time passwords + are typically generated cryptographically. Therefore, this is a + type of "cryptographic token", and the key is a type of + "authentication information".) + - NIST "soft token": A cryptographic key that typically is stored + on disk or some other magnetic media. (The key is a type of + "authentication information"; "authentication key" would be a + better description.) + - NIST "password token": A secret data value that the claimant + memorizes. (This is a "password" that is being used as + "authentication information".) + + $ token backup + (I) A token management operation that stores sufficient + information in a database (e.g., in a CAW) to recreate or restore + a security token (e.g., a smart card) if it is lost or damaged. + + $ token copy + (I) A token management operation that copies all the personality + information from one security token to another. However, unlike in + a token restore operation, the second token is initialized with + its own, different local security values such as PINs and storage + keys. + + $ token management + (I) The process that includes initializing security tokens (e.g., + "smart card"), loading data into the tokens, and controlling the + tokens during their lifecycle. May include performing key + management and certificate management functions; generating and + installing PINs; loading user personality data; performing card + backup, card copy, and card restore operations; and updating + firmware. + + + + + + +Shirey Informational [Page 309] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ token restore + (I) A token management operation that loads a security token with + data for the purpose of recreating (duplicating) the contents + previously held by that or another token. (See: recovery.) + + $ token storage key + (I) A cryptographic key used to protect data that is stored on a + security token. + + $ top CA + (I) Synonym for "root" in a certification hierarchy. (See: apex + trust anchor.) + + $ top-level specification + (I) "A non-procedural description of system behavior at the most + abstract level; typically a functional specification that omits + all implementation details." [NCS04] (See: formal top-level + specification, Tutorial under "security policy".) + + Tutorial: A top-level specification is at a level of abstraction + below "security model" and above "security architecture" (see: + Tutorial under "security policy"). + + A top-level specification may be descriptive or formal: + - "Descriptive top-level specification": One that is written in a + natural language like English or an informal design notation. + - "Formal top-level specification": One that is written in a + formal mathematical language to enable theorems to be proven + that show that the specification correctly implements a set of + formal requirements or a formal security model. (See: + correctness proof.) + + $ TPM + (N) See: Trusted Platform Module. + + $ traceback + (I) Identification of the source of a data packet. (See: + masquerade, network weaving.) + + $ tracker + (N) An attack technique for achieving unauthorized disclosure from + a statistical database. [Denns] (See: Tutorial under "inference + control".) + + $ traffic analysis + 1. (I) Gaining knowledge of information by inference from + observable characteristics of a data flow, even if the information + is not directly available (e.g., when the data is encrypted). + + + +Shirey Informational [Page 310] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + These characteristics include the identities and locations of the + source(s) and destination(s) of the flow, and the flow's presence, + amount, frequency, and duration of occurrence. The object of the + analysis might be information in SDUs, information in the PCI, or + both. (See: inference, traffic-flow confidentiality, wiretapping. + Compare: signal analysis.) + + 2. (O) "The inference of information from observation of traffic + flows (presence, absence, amount, direction, and frequency)." + [I7498-2] + + $ traffic-flow analysis + (I) Synonym for "traffic analysis". + + $ traffic-flow confidentiality (TFC) + 1. (I) A data confidentiality service to protect against traffic + analysis. (See: communications cover.) + + 2. (O) "A confidentiality service to protect against traffic + analysis." [I7498-2] + + Tutorial: Confidentiality concerns involve both direct and + indirect disclosure of data, and the latter includes traffic + analysis. However, operational considerations can make TFC + difficult to achieve. For example, if Alice sends a product idea + to Bob in an email message, she wants data confidentiality for the + message's content, and she might also want to conceal the + destination of the message to hide Bob's identity from her + competitors. However, the identity of the intended recipient, or + at least a network address for that recipient, needs to be made + available to the mail system. Thus, complex forwarding schemes may + be needed to conceal the ultimate destination as the message + travels through the open Internet (see: onion routing). + + Later, if Alice uses an ATM during a clandestine visit to + negotiate with Bob, she might prefer that her bank conceal the + origin of her transaction, because knowledge of the ATM's location + might allow a competitor to infer Bob's identity. The bank, on the + other hand, might prefer to protect only Alice's PIN (see: + selective-field confidentiality). + + A TFC service can be either full or partial: + - "Full TFC": This type of service conceals all traffic + characteristics. + - "Partial TFC": This type of service either (a) conceals some + but not all of the characteristics or (b) does not completely + conceal some characteristic. + + + + +Shirey Informational [Page 311] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + On point-to-point data links, full TFC can be provided by + enciphering all PDUs and also generating a continuous, random data + stream to seamlessly fill all gaps between PDUs. To a wiretapper, + the link then appears to be carrying an unbroken stream of + enciphered data. In other cases -- including on a shared or + broadcast medium, or end-to-end in a network -- only partial TFC + is possible, and that may require a combination of techniques. For + example, a LAN that uses "carrier sense multiple access with + collision detection" (CSMA/CD; a.k.a. "listen while talk") to + control access to the medium, relies on detecting intervals of + silence, which prevents using full TFC. Partial TFC can be + provided on that LAN by measures such as adding spurious PDUs, + padding PDUs to a constant size, or enciphering addresses just + above the Physical Layer; but these measures reduce the efficiency + with which the LAN can carry traffic. At higher protocol layers, + SDUs can be protected, but addresses and other items of PCI must + be visible at the layers below. + + $ traffic key + (I) A cryptographic key used by a device for protecting + information that is being transmitted between devices, as opposed + to protecting information that being is maintained in the device. + (Compare: storage key.) + + $ traffic padding + (I) "The generation of spurious instances of communication, + spurious data units, and/or spurious data within data units." + [I7498-2] + + $ tranquility property + (N) /formal model/ Property of a system whereby the security level + of an object cannot change while the object is being processed by + the system. (See: Bell-LaPadula model.) + + $ transaction + 1. (I) A unit of interaction between an external entity and a + system, or between components within a system, that involves a + series of system actions or events. + + 2. (O) "A discrete event between user and systems that supports a + business or programmatic purpose." [M0404] + + Tutorial: To maintain secure state, transactions need to be + processed coherently and reliably. Usually, they need to be + designed to be atomic, consistent, isolated, and durable [Gray]: + - "Atomic": All actions and events that comprise the transaction + are guaranteed to be completed successfully, or else the result + is as if none at all were executed. + + + +Shirey Informational [Page 312] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + - "Consistent": The transaction satisfies correctness constraints + defined for the data that is being processed. + - "Isolated": If two transactions are performed concurrently, + they do not interfere with each other, and it appears as though + the system performs one at a time. + - "Durable": System state and transaction semantics survive + system failures. + + $ TRANSEC + (I) See: transmission security. + + $ Transmission Control Code field (TCC field) + (I) A data field that provides a means to segregate traffic and + define controlled communities of interest in the security option + (option type = 130) of IPv4's datagram header format. The TCC + values are alphanumeric trigraphs assigned by the U.S. Government + as specified in RFC 791. + + $ Transmission Control Protocol (TCP) + (I) An Internet Standard, Transport-Layer protocol (RFC 793) that + reliably delivers a sequence of datagrams from one computer to + another in a computer network. (See: TCP/IP.) + + Tutorial: TCP is designed to fit into a layered suite of protocols + that support internetwork applications. TCP assumes it can obtain + a simple but potentially unreliable end-to-end datagram service + (such as IP) from the lower-layer protocols. + + $ transmission security (TRANSEC) + (I) COMSEC measures that protect communications from interception + and exploitation by means other than cryptanalysis. Example: + frequency hopping. (Compare: anti-jam, traffic flow + confidentiality.) + + $ Transport Layer + See: Internet Protocol Suite, OSIRM. + + $ Transport Layer Security (TLS) + (I) TLS is an Internet protocol [R4346] that is based on, and very + similar to, SSL Version 3.0. (Compare: TLSP.) + + Tutorial: The TLS protocol is misnamed. The name misleadingly + suggests that TLS is situated in the IPS Transport Layer, but TLS + is always layered above a reliable Transport-Layer protocol + (usually TCP) and either layered immediately below or integrated + with an Application-Layer protocol (often HTTP). + + + + + +Shirey Informational [Page 313] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ Transport Layer Security Protocol (TLSP) + (N) An end-to-end encryption protocol (ISO 10736) that provides + security services at the bottom of OSIRM Layer 4, i.e., directly + above Layer 3. (Compare: TLS.) + + Tutorial: TLSP evolved directly from SP4. + + $ transport mode + (I) One of two ways to apply AH or ESP to protect data packets; in + this mode, the IPsec protocol encapsulates (i.e., the protection + applies to) the packets of an IPS Transport-Layer protocol (e.g., + TCP, UDP), which normally is carried directly above IP in an IPS + protocol stack. (Compare: tunnel mode.) + + Tutorial: An IPsec transport-mode security association is always + between two hosts; neither end has the role of a security gateway. + Whenever either end of an IPsec security association is a security + gateway, the association is required to be in tunnel mode. + + $ transposition + (I) /cryptography/ A method of encryption in which elements of the + plain text retain their original form but undergo some change in + their sequential position. (Compare: substitution.) + + $ trap door + (I) Synonym for "back door". + + $ trespass + (I) /threat action/ See: secondary definition under "intrusion". + + $ Triple Data Encryption Algorithm + (I) A block cipher that transforms each 64-bit plaintext block by + applying the DEA three successive times, using either two or three + different keys for an effective key length of 112 or 168 bits. + [A9052, SP67] + + Example: A variation proposed for IPsec's ESP uses a 168-bit key, + consisting of three independent 56-bit values used by the DEA, and + a 64-bit initialization vector. Each datagram contains an IV to + ensure that each received datagram can be decrypted even when + other datagrams are dropped or a sequence of datagrams is + reordered in transit. [R1851] + + $ triple-wrapped + (I) /S-MIME/ Data that has been signed with a digital signature, + then encrypted, and then signed again. [R2634] + + + + + +Shirey Informational [Page 314] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ Trojan horse + (I) A computer program that appears to have a useful function, but + also has a hidden and potentially malicious function that evades + security mechanisms, sometimes by exploiting legitimate + authorizations of a system entity that invokes the program. (See: + malware, spyware. Compare: logic bomb, virus, worm.) + + $ trust + 1. (I) /information system/ A feeling of certainty (sometimes + based on inconclusive evidence) either (a) that the system will + not fail or (b) that the system meets its specifications (i.e., + the system does what it claims to do and does not perform unwanted + functions). (See: trust level, trusted system, trustworthy system. + Compare: assurance.) + + Tutorial: Components of a system can be grouped into three classes + of trust [Gass]: + - "Trusted": The component is responsible for enforcing security + policy on other components; the system's security depends on + flawless operation of the component. (See: trusted process.) + - "Benign": The component is not responsible for enforcing + security policy, but it has sensitive authorizations. It must + be trusted not to intentionally violate security policy, but + security violations are assumed to be accidental and not likely + to affect overall system security. + - "Untrusted": The component is of unknown or suspicious + provenance and must be treated as deliberately malicious. (See: + malicious logic.) + + 2. (I) /PKI/ A relationship between a certificate user and a CA in + which the user acts according to the assumption that the CA + creates only valid digital certificates. + + Tutorial: "Generally, an entity is said to 'trust' a second entity + when the first entity makes the assumption that the second entity + will behave exactly as the first entity expects. This trust may + apply only for some specific function. The key role of trust in + [X.509] is to describe the relationship between an entity [i.e., a + certificate user] and a [CA]; an entity shall be certain that it + can trust the CA to create only valid and reliable certificates." + [X509] + + $ trust anchor + (I) /PKI/ An established point of trust (usually based on the + authority of some person, office, or organization) from which a + certificate user begins the validation of a certification path. + (See: apex trust anchor, path validation, trust anchor CA, trust + anchor certificate, trust anchor key.) + + + +Shirey Informational [Page 315] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Usage: IDOCs that use this term SHOULD state a definition for it + because it is used in various ways in existing IDOCs and other PKI + literature. The literature almost always uses this term in a sense + that is equivalent to this definition, but usage often differs + with regard to what constitutes the point of trust. + + Tutorial: A trust anchor may be defined as being based on a public + key, a CA, a public-key certificate, or some combination or + variation of those: + + - 1. A public key as a point of trust: Although a certification + path is defined as beginning with a "sequence of public-key + certificates", an implementation of a path validation process + might not explicitly handle a root certificate as part of the + path, but instead begin the process by using a trusted root key + to verify the signature on a certificate that was issued by the + root. + + Therefore, "trust anchor" is sometimes defined as just a public + key. (See: root key, trust anchor key, trusted key.) + + - 2. A CA as a point of trust: A trusted public key is just one + of the data elements needed for path validation; the IPS path + validation algorithm [R3280] also needs the name of the CA to + which that key belongs, i.e., the DN of the issuer of the first + X.509 certificate to be validated on the path. (See: issue.) + + Therefore, "trust anchor" is sometimes defined as either just a + CA (where some public key is implied) or as a CA together with + a specified public key belonging to that CA. (See: root, trust + anchor CA, trusted CA.) + + Example: "A public key and the name of a [CA] that is used to + validate the first certificate in a sequence of certificates. + The trust anchor public key is used to verify the signature on + a certificate issued by a trust anchor [CA]." [SP57] + + - 3. A public-key certificate as a point of trust: Besides the + trusted CA's public key and name, the path validation algorithm + needs to know the digital signature algorithm and any + associated parameters with which the public key is used, and + also any constraints that have been placed on the set of paths + that may be validated using the key. All of this information is + available from a CA's public-key certificate. + + Therefore, "trust anchor" is sometimes defined as a public-key + certificate of a CA. (See: root certificate, trust anchor + certificate, trusted certificate.) + + + +Shirey Informational [Page 316] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + - 4. Combinations: Combinations and variations of the first three + definitions are also used in the PKI literature. + + Example: "trust anchor information". The IPS standard for path + validation [R3280] specifies the information that describes "a + CA that serves as a trust anchor for the certification path. + The trust anchor information includes: (a) the trusted issuer + name, (b) the trusted public key algorithm, (c) the trusted + public key, and (d) optionally, the trusted public key + parameters associated with the public key. The trust anchor + information may be provided to the path processing procedure in + the form of a self-signed certificate. The trusted anchor + information is trusted because it was delivered to the path + processing procedure by some trustworthy out-of-band procedure. + If the trusted public key algorithm requires parameters, then + the parameters are provided along with the trusted public key." + + $ trust anchor CA + (I) A CA that is the subject of a trust anchor certificate or + otherwise establishes a trust anchor key. (See: root, trusted CA.) + + Tutorial: The selection of a CA to be a trust anchor is a matter + of policy. Some of the possible choices include (a) the top CA in + a hierarchical PKI, (b) the CA that issued the verifier's own + certificate, or (c) any other CA in a network PKI. Different + applications may rely on different trust anchors, or may accept + paths that begin with any of a set of trust anchors. The IPS path + validation algorithm is the same, regardless of the choice. + + $ trust anchor certificate + (I) A public-key certificate that is used to provide the first + public key in a certification path. (See: root certificate, trust + anchor, trusted certificate.) + + $ trust anchor key + (I) A public key that is used as the first public key in a + certification path. (See: root key, trust anchor, trusted public + key.) + + $ trust anchor information + (I) See: secondary definition under "trust anchor". + + $ trust chain + (D) Synonym for "certification path". (See: trust anchor, trusted + certificate.) + + + + + + +Shirey Informational [Page 317] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Deprecated Term: IDOCs SHOULD NOT use this term, because it + unnecessarily duplicates the meaning of the internationally + standardized term. + + Also, the term mixes concepts in a potentially misleading way. + Having "trust" involves factors unrelated to simply verifying + signatures and performing other tests as specified by a standard + algorithm for path validation (e.g., RFC 3280). Thus, even if a + user is able to validate a certification path algorithmically, the + user still might distrust one of the CAs that issued certificates + in that path or distrust some other aspects of the PKI. + + $ trust-file PKI + (I) A non-hierarchical PKI in which each certificate user has its + own local file (which is used by application software) of trust + anchors, i.e., either public keys or public-key certificates that + the user trusts as starting points for certification paths. (See: + trust anchor, web of trust. Compare: hierarchical PKI, mesh PKI.) + + Example: Popular browsers are distributed with an initial file of + trust anchor certificates, which often are self-signed + certificates. Users can add certificates to the file or delete + from it. The file may be directly managed by the user, or the + user's organization may manage it from a centralized server. + + $ trust hierarchy + (D) Synonym for "certification hierarchy". + + Deprecated Usage: IDOCs SHOULD NOT use this term because it mixes + concepts in a potentially misleading way, and because a trust + hierarchy could be implemented in other ways. (See: trust, trust + chain, web of trust.) + + $ trust level + (N) A characterization of a standard of security protection to be + met by an information system. (See: Common Criteria, TCSEC.) + + Tutorial: A trust level is based not only on (a) the presence of + security mechanisms, but also on the use of (b) systems + engineering discipline to properly structure the system and (c) + implementation analysis to ensure that the system provides an + appropriate degree of trust. + + $ trusted + (I) See: secondary definition under "trust". + + + + + + +Shirey Informational [Page 318] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ trusted CA + (I) A CA upon which a certificate user relies as issuing valid + certificates; especially a CA that is used as a trust anchor CA. + (See: certification path, root, trust anchor CA, validation.) + + Tutorial. This trust is transitive to the extent that the X.509 + certificate extensions permit; that is, if a trusted CA issues a + certificate to another CA, a user that trusts the first CA also + trusts the second CA if the user succeeds in validating the + certificate path (see: path validation). + + $ trusted certificate + (I) A digital certificate that a certificate user accepts as being + valid "a priori", i.e., without testing the certificate to + validate it as the final certificate on a certification path; + especially a certificate that is used as a trust anchor + certificate. (See: certification path, root certificate, trust + anchor certificate, trust-file PKI, validation.) + + Tutorial: The acceptance of a certificate as trusted is a matter + of policy and choice. Usually, a certificate is accepted as + trusted because the user obtained it by reliable, out-of-band + means that cause the user to believe the certificate accurately + binds its subject's name to the subject's public key or other + attribute values. Many choices are possible; e.g., a trusted + public-key certificate might be (a) the root certificate in a + hierarchical PKI, (b) the certificate of the CA that issued the + user's own certificate in a mesh PKI, or (c) a certificate + provided with an application that uses a trust-file PKI. + + $ Trusted Computer System Evaluation Criteria (TCSEC) + (N) A standard for evaluating the security provided by operating + systems [CSC1, DoD1]. Known as the "Orange Book" because of the + color of its cover; first document in the Rainbow Series. (See: + Common Criteria, Deprecated Usage under "Green Book", Orange Book, + trust level, trusted system. Compare: TSEC.) + + Tutorial: The TCSEC defines classes of hierarchically ordered + assurance levels for rating computer systems. From highest to + lowest, the classes are as follows: + - Division A: Verified protection. + Beyond A1 Beyond current technology. (See: beyond A1.) + Class A1 Verified design. (See: SCOMP.) + - Division B: Mandatory protection. + Class B3 Security domains. + Class B2 Structured protection. (See: Multics.) + Class B1 Labeled security protection. + + + + +Shirey Informational [Page 319] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + - Division C: Discretionary protection. + Class C2 Controlled access protection. + Class C1 Discretionary security protection. + - Division D: Minimal protection, i.e., has been evaluated but + does not meet the requirements for a higher evaluation class. + + $ trusted computing base (TCB) + (N) "The totality of protection mechanisms within a computer + system, including hardware, firmware, and software, the + combination of which is responsible for enforcing a security + policy." [NCS04] (See: "trusted" under "trust". Compare: TPM.) + + $ Trusted Computing Group (TCG) + (N) A not-for-profit, industry standards organization formed to + develop, define, and promote open standards for hardware-enabled + trusted computing and security technologies, including hardware + building blocks and software interfaces, across multiple + platforms, peripherals, and devices. (See: TPM, trusted system. + Compare: TSIG.) + + $ trusted distribution + (I) /COMPUSEC/ "A trusted method for distributing the TCB + hardware, software, and firmware components, both originals and + updates, that provides methods for protecting the TCB from + modification during distribution and for detection of any changes + to the TCB that may occur." [NCS04] (See: code signing, + configuration control.) + + $ trusted key + (D) Abbreviation for "trusted public key" and also for other types + of keys. (See: root key, trust anchor key.) + + Deprecated Usage: IDOCs SHOULD either (a) state a definition for + this term or (b) use a different, less ambiguous term. This term + is ambiguous when it stands alone; e.g., it could refer to a + trusted public key or to a private key or symmetric key that is + believed to be secure (i.e., not compromised). + + $ trusted path + 1a. (I) /COMPUSEC/ A mechanism by which a computer system user can + communicate directly and reliably with the TCB and that can only + be activated by the user or the TCB and cannot be imitated by + untrusted software within the computer. [NCS04] + + 1b. (I) /COMSEC/ A mechanism by which a person or process can + communicate directly with a cryptographic module and that can only + be activated by the person, process, or module, and cannot be + imitated by untrusted software within the module. [FP140] + + + +Shirey Informational [Page 320] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ Trusted Platform Module (TPM) + (N) The name of a specification, published by the TCG, for a + microcontroller that can store secured information; and also the + general name of implementations of that specification. (Compare: + TCB.) + + $ trusted process + (I) A system component that has privileges that enable it to + affect the state of system security and that can, therefore, + through incorrect or malicious execution, violate the system's + security policy. (See: privileged process, trusted system.) + + $ trusted public key + (I) A public key upon which a user relies; especially a public key + that is used as a trust anchor key. (See: certification path, root + key, trust anchor key, validation.) + + Tutorial: A trusted public key could be (a) the root key in a + hierarchical PKI, (b) the key of the CA that issued the user's own + certificate in a mesh PKI, or (c) any key accepted by the user in + a trust-file PKI. + + $ trusted recovery + (I) A process that, after a system has experienced a failure or an + attack, restores the system to normal operation (or to a secure + state) without causing a security compromise. (See: recovery.) + + $ trusted subnetwork + (I) A subnetwork containing hosts and routers that trust each + other not to engage in active or passive attacks. (There also is + an assumption that the underlying communication channels, such as + telephone lines or a LAN, are protected from attack.) + + $ trusted system + 1. (I) /information system/ A system that operates as expected, + according to design and policy, doing what is required -- despite + environmental disruption, human user and operator errors, and + attacks by hostile parties -- and not doing other things [NRC98]. + (See: trust level, trusted process. Compare: trustworthy.) + + 2. (N) /multilevel secure/ "A [trusted system is a] system that + employs sufficient hardware and software assurance measures to + allow its use for simultaneous processing of a range of sensitive + or classified information." [NCS04] (See: multilevel security + mode.) + + + + + + +Shirey Informational [Page 321] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ Trusted Systems Interoperability Group (TSIG) + (N) A forum of computer vendors, system integrators, and users + devoted to promoting interoperability of trusted computer systems. + (See: trusted system. Compare: TCG.) + + $ trustworthy system + 1. (I) A system that not only is trusted, but also warrants that + trust because the system's behavior can be validated in some + convincing way, such as through formal analysis or code review. + (See: trust. Compare: trusted.) + + 2. (O) /Digital Signature Guidelines/ "Computer hardware, + software, and procedures that: (a) are reasonably secure from + intrusion and misuse; (b) provide a reasonably reliable level of + availability, reliability, and correct operation; (c) are + reasonably suited to performing their intended functions; and (d) + adhere to generally accepted security principles." [DSG] + + $ TSEC + (O) See: Telecommunications Security Nomenclature System. + (Compare: TCSEC.) + + $ TSIG + 1. (N) See: Trusted System Interoperability Group. + + 2. (I) A mnemonic (presumed to be derived from "Transaction + SIGnature") referring to an Internet protocol (RFC 2845) for data + origin authentication and data integrity for certain DNS + operations. (See: TKEY.) + + $ tunnel + 1. (I) A communication channel created in a computer network by + encapsulating (i.e., layering) a communication protocol's data + packets in (i.e., above) a second protocol that normally would be + carried above, or at the same layer as, the first one. (See: L2TP, + tunnel mode, VPN. Compare: covert channel.) + + Tutorial: Tunneling can involve almost any two IPS protocol + layers. For example, a TCP connection between two hosts could + conceivably be carried above SMTP (i.e., in SMTP messages) as a + covert channel to evade access controls that a security gateway + applies to the normal TCP layer that is below SMTP. + + Usually, however, a tunnel is a logical point-to-point link -- + i.e., an OSIRM Layer 2 connection -- created by encapsulating the + Layer 2 protocol in one of the following three types of IPS + protocols: (a) an IPS Transport-Layer protocol (such as TCP), (b) + an IPS Network-Layer or Internet-Layer protocol (such as IP), or + + + +Shirey Informational [Page 322] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + (c) another Layer 2 protocol. In many cases, the encapsulation is + accomplished with an extra, intermediate protocol (i.e., a + "tunneling protocol"; e.g., L2TP) that is layered below the + tunneled Layer 2 protocol and above the encapsulating protocol. + + Tunneling can be used to move data between computers that use a + protocol not supported by the network connecting them. Tunneling + also can enable a computer network to use the services of a second + network as though the second network were a set of point-to-point + links between the first network's nodes. (See: VPN.) + + 2. (O) /SET/ The name of a SET private extension that indicates + whether the CA or the payment gateway supports passing encrypted + messages to the cardholder through the merchant. If so, the + extension lists OIDs of symmetric encryption algorithms that are + supported. + + $ tunnel mode + (I) One of two ways to apply the IPsec protocols (AH and ESP) to + protect data packets; in this mode, the IPsec protocol + encapsulates (i.e., the protection applies to) IP packets, rather + than the packets of higher-layer protocols. (See: tunnel. Compare: + transport mode.) + + Tutorial: Each end of a tunnel-mode security association may be + either a host or a security gateway. Whenever either end of an + IPsec security association is a security gateway, the association + is required to be in tunnel mode. + + $ two-person control + (I) The close surveillance and control of a system, a process, or + materials (especially with regard to cryptography) at all times by + a minimum of two appropriately authorized persons, each capable of + detecting incorrect and unauthorized procedures with respect to + the tasks to be performed and each familiar with established + security requirements. (See: dual control, no-lone zone.) + + $ Twofish + (O) A symmetric, 128-bit block cipher with variable key length + (128, 192, or 256 bits), developed by Counterpane Labs as a + candidate for the AES. (See: Blowfish.) + + $ type 0 product + (O) /cryptography, U.S. Government/ Classified cryptographic + equipment endorsed by NSA for use (when appropriately keyed) in + electronically distributing bulk keying material. + + + + + +Shirey Informational [Page 323] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ type 1 key + (O) /cryptography, U.S. Government/ "Generated and distributed + under the auspices of NSA for use in a cryptographic device for + the protection of classified and sensitive national security + information." [C4009] + + $ type 1 product + (O) /cryptography, U.S. Government/ "Cryptographic equipment, + assembly or component classified or certified by NSA for + encrypting and decrypting classified and sensitive national + security information when appropriately keyed. Developed using + established NSA business processes and containing NSA approved + algorithms. Used to protect systems requiring the most stringent + protection mechanisms." [C4009] + + Tutorial: The current definition of this term is less specific + than an earlier version: "Classified or controlled cryptographic + item endorsed by the NSA for securing classified and sensitive + U.S. Government information, when appropriately keyed. The term + refers only to products, and not to information, key, services, or + controls. Type 1 products contain classified NSA algorithms. They + are available to U.S. Government users, their contractors, and + federally sponsored non-U.S. Government activities subject to + export restrictions in accordance with International Traffic in + Arms Regulation." [from an earlier version of C4009] (See: ITAR.) + + $ type 2 key + (O) /cryptography, U.S. Government/ "Generated and distributed + under the auspices of NSA for use in a cryptographic device for + the protection of unclassified national security information." + [C4009] + + $ type 2 product + (O) /cryptography, U.S. Government/ "Cryptographic equipment, + assembly, or component certified by NSA for encrypting or + decrypting sensitive national security information when + appropriately keyed. Developed using established NSA business + processes and containing NSA approved algorithms. Used to protect + systems requiring protection mechanisms exceeding best commercial + practices including systems used for the protection of + unclassified national security information." [C4009] + + Tutorial: The current definition of this term is less specific + than an earlier version: "Unclassified cryptographic equipment, + assembly, or component, endorsed by the NSA, for use in national + security systems as defined in Title 40 U.S.C. Section 1452." + [from an earlier version of C4009] (See: national security system. + Compare: EUCI.) + + + +Shirey Informational [Page 324] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ type 3 key + (O) /cryptography, U.S. Government/ "Used in a cryptographic + device for the protection of unclassified sensitive information, + even if used in a Type 1 or Type 2 product." [C4009] + + $ type 3 product + (O) /cryptography, U.S. Government/ "Unclassified cryptographic + equipment, assembly, or component used, when appropriately keyed, + for encrypting or decrypting unclassified sensitive U.S. + Government or commercial information, and to protect systems + requiring protection mechanisms consistent with standard + commercial practices. Developed using established commercial + standards and containing NIST approved cryptographic + algorithms/modules or successfully evaluated by the National + Information Assurance Partnership (NIAP)." [C4009] + + $ type 4 key + (O) /cryptography, U.S. Government/ "Used by a cryptographic + device in support of its Type 4 functionality; i.e., any provision + of key that lacks U.S. Government endorsement or oversight." + [C4009] + + $ type 4 product + (O) /cryptography, U.S. Government/ "Unevaluated commercial + cryptographic equipment, assemblies, or components that neither + NSA nor NIST certify for any Government usage. These products are + typically delivered as part of commercial offerings and are + commensurate with the vendor's commercial practices. These + products may contain either vendor proprietary algorithms, + algorithms registered by NIST, or algorithms registered by NIST + and published in a FIPS." [C4009] + + $ UDP + (I) See: User Datagram Protocol. + + $ UDP flood + (I) A denial-of-service attack that takes advantage of (a) one + system's UDP test function that generates a series of characters + for each packet it receives and (b) another system's UPD test + function that echoes any character it receives; the attack + connects (a) to (b) to cause a nonstop flow of data between the + two systems. (See: flooding.) + + $ unauthorized disclosure + (I) A circumstance or event whereby an entity gains access to + information for which the entity is not authorized. + + + + + +Shirey Informational [Page 325] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Tutorial: This type of threat consequence can be caused by the + following types of threat actions: exposure, interception, + inference, and intrusion. Some methods of protecting against this + consequence include access control, flow control, and inference + control. (See: data confidentiality.) + + $ unauthorized user + (I) /access control/ A system entity that accesses a system + resource for which the entity has not received an authorization. + (See: user. Compare: authorized user, insider, outsider.) + + Usage: IDOCs that use this term SHOULD state a definition for it + because the term is used in many ways and could easily be + misunderstood. + + $ uncertainty + (N) An information-theoretic measure (usually stated as a number + of bits) of the minimum amount of plaintext information that needs + to be recovered from cipher text to learn the entire plain text + that was encrypted. [SP63] (See: entropy.) + + $ unclassified + (I) Not classified. (Compare: FOUO.) + + $ unencrypted + (I) Not encrypted. + + $ unforgeable + (I) /cryptography/ The property of a cryptographic data structure + (i.e., a data structure that is defined using one or more + cryptographic functions, e.g., "digital certificate") that makes + it computationally infeasible to construct (i.e., compute) an + unauthorized but correct value of the structure without having + knowledge of one of more keys. + + Tutorial: This definition is narrower than general English usage, + where "unforgeable" means unable to be fraudulently created or + duplicated. In that broader sense, anyone can forge a digital + certificate containing any set of data items whatsoever by + generating the to-be-signed certificate and signing it with any + private key whatsoever. But for PKI purposes, the forged data + structure is invalid if it is not signed with the true private key + of the claimed issuer; thus, the forgery will be detected when a + certificate user uses the true public key of the claimed issuer to + verify the signature. + + + + + + +Shirey Informational [Page 326] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ uniform resource identifier (URI) + (I) A type of formatted identifier (RFC 3986) that encapsulates + the name of an Internet object, and labels it with an + identification of the name space, thus producing a member of the + universal set of names in registered name spaces and of addresses + referring to registered protocols or name spaces. + + Example: HTML uses URIs to identify the target of hyperlinks. + + Usage: "A URI can be classified as a locator (see: URL), a name + (see: URN), or both. ... Instances of URIs from any given scheme + may have the characteristics of names or locators or both, often + depending on the persistence and care in the assignment of + identifiers by the naming authority, rather than on any quality of + the scheme." IDOCs SHOULD "use the general term 'URI' rather than + the more restrictive terms 'URL' and 'URN'." (RFC 3986) + + $ uniform resource locator (URL) + (I) A URI that describes the access method and location of an + information resource object on the Internet. (See: Usage under + "URI". Compare: URN.) + + Tutorial: The term URL "refers to the subset of URIs that, besides + identifying a resource, provide a means of locating the resource + by describing its primary access mechanism (e.g., its network + 'location')." (RFC 3986) + + A URL provides explicit instructions on how to access the named + object. For example, + "ftp://bbnarchive.bbn.com/foo/bar/picture/cambridge.zip" is a URL. + The part before the colon specifies the access scheme or protocol, + and the part after the colon is interpreted according to that + access method. Usually, two slashes after the colon indicate the + host name of a server (written as a domain name). In an FTP or + HTTP URL, the host name is followed by the path name of a file on + the server. The last (optional) part of a URL may be either a + fragment identifier that indicates a position in the file, or a + query string. + + $ uniform resource name (URN) + (I) A URI with the properties of a name. (See: Usage under "URI". + Compare: URL.) + + Tutorial: The term URN "has been used historically to refer to + both URIs under the "urn" scheme (RFC 2141), which are required to + remain globally unique and persistent even when the resource + ceases to exist or becomes unavailable, and to any other URI with + the properties of a name." (RFC 3986) + + + +Shirey Informational [Page 327] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ untrusted + (I) See: secondary definition under "trust". + + $ untrusted process + 1. (I) A system component that is not able to affect the state of + system security through incorrect or malicious operation. Example: + A component that has its operations confined by a security kernel. + (See: trusted process.) + + 2. (I) A system component that (a) has not been evaluated or + examined for adherence to a specified security policy and, + therefore, (b) must be assumed to contain logic that might attempt + to circumvent system security. + + $ UORA + (O) See: user-PIN ORA. + + $ update + See: "certificate update" and "key update". + + $ upgrade + (I) /data security/ Increase the classification level of data + without changing the information content of the data. (See: + classify, downgrade, regrade.) + + $ URI + (I) See: uniform resource identifier. + + $ URL + (I) See: uniform resource locator. + + $ URN + (I) See: uniform resource name. + + $ user + See: system user. + + Usage: IDOCs that use this term SHOULD state a definition for it + because the term is used in many ways and could easily be + misunderstood. + + $ user authentication service + (I) A security service that verifies the identity claimed by an + entity that attempts to access the system. (See: authentication, + user.) + + + + + + +Shirey Informational [Page 328] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ User Datagram Protocol (UDP) + (I) An Internet Standard, Transport-Layer protocol (RFC 768) that + delivers a sequence of datagrams from one computer to another in a + computer network. (See: UPD flood.) + + Tutorial: UDP assumes that IP is the underlying protocol. UDP + enables application programs to send transaction-oriented data to + other programs with minimal protocol mechanism. UDP does not + provide reliable delivery, flow control, sequencing, or other end- + to-end service guarantees that TCP does. + + $ user identifier + (I) See: identifier. + + $ user identity + (I) See: identity. + + $ user PIN + (O) /MISSI/ One of two PINs that control access to the functions + and stored data of a FORTEZZA PC card. Knowledge of the user PIN + enables a card user to perform the FORTEZZA functions that are + intended for use by an end user. (See: PIN. Compare: SSO PIN.) + + $ user-PIN ORA (UORA) + (O) /MISSI/ A MISSI organizational RA that operates in a mode in + which the ORA performs only the subset of card management + functions that are possible with knowledge of the user PIN for a + FORTEZZA PC card. (See: no-PIN ORA, SSO-PIN ORA.) + + $ usurpation + (I) A circumstance or event that results in control of system + services or functions by an unauthorized entity. This type of + threat consequence can be caused by the following types of threat + actions: misappropriation, misuse. (See: access control.) + + $ UTCTime + (N) The ASN.1 data type "UTCTime" contains a calendar date + (YYMMDD) and a time to a precision of either one minute (HHMM) or + one second (HHMMSS), where the time is either (a) Coordinated + Universal Time or (b) the local time followed by an offset that + enables Coordinated Universal Time to be calculated. (See: + Coordinated Universal Time. Compare: GeneralizedTime.) + + Usage: If you care about centuries or millennia, you probably need + to use the GeneralizedTime data type instead of UTCTime. + + + + + + +Shirey Informational [Page 329] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ v1 certificate + (N) An abbreviation that ambiguously refers to either an "X.509 + public-key certificate in version 1 format" or an "X.509 attribute + certificate in version 1 format". + + Deprecated Usage: IDOCs MAY use this term as an abbreviation of + "version 1 X.509 public-key certificate", but only after using the + full term at the first instance. Otherwise, the term is ambiguous, + because X.509 specifies both v1 public-key certificates and v1 + attribute certificates. (See: X.509 attribute certificate, X.509 + public-key certificate.) + + $ v1 CRL + (N) Abbreviation of "X.509 CRL in version 1 format". + + Usage: IDOCs MAY use this abbreviation, but SHOULD use the full + term at its first occurrence and define the abbreviation there. + + $ v2 certificate + (N) Abbreviation of "X.509 public-key certificate in version 2 + format". + + Usage: IDOCs MAY use this abbreviation, but SHOULD use the full + term at its first occurrence and define the abbreviation there. + + $ v2 CRL + (N) Abbreviation of "X.509 CRL in version 2 format". + + Usage: IDOCs MAY use this abbreviation, but SHOULD use the full + term at its first occurrence and define the abbreviation there. + + $ v3 certificate + (N) Abbreviation of "X.509 public-key certificate in version 3 + format". + + Usage: IDOCs MAY use this abbreviation, but SHOULD use the full + term at its first occurrence and define the abbreviation there. + + $ valid certificate + 1. (I) A digital certificate that can be validated successfully. + (See: validate, verify.) + + 2. (I) A digital certificate for which the binding of the data + items can be trusted. + + $ valid signature + (D) Synonym for "verified signature". + + + + +Shirey Informational [Page 330] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Deprecated Term: IDOCs SHOULD NOT use this synonym. This Glossary + recommends saying "validate the certificate" and "verify the + signature"; therefore, it would be inconsistent to say that a + signature is "valid". (See: validate, verify.) + + $ validate + 1. (I) Establish the soundness or correctness of a construct. + Example: certificate validation. (See: validate vs. verify.) + + 2. (I) To officially approve something, sometimes in relation to a + standard. Example: NIST validates cryptographic modules for + conformance with [FP140]. + + $ validate vs. verify + Usage: To ensure consistency and align with ordinary English + usage, IDOCs SHOULD comply with the following two rules: + - Rule 1: Use "validate" when referring to a process intended to + establish the soundness or correctness of a construct (e.g., + "certificate validation"). (See: validate.) + - Rule 2: Use "verify" when referring to a process intended to + test or prove the truth or accuracy of a fact or value (e.g., + "authenticate"). (See: verify.) + + Tutorial: The Internet security community sometimes uses these two + terms inconsistently, especially in a PKI context. Most often, + however, we say "verify the signature" but say "validate the + certificate". That is, we "verify" atomic truths but "validate" + data structures, relationships, and systems that are composed of + or depend on verified items. This usage has a basis in Latin: + + The word "valid" derives from a Latin word that means "strong". + Thus, to validate means to check that a construct is sound. For + example, a certificate user validates a public-key certificate to + establish trust in the binding that the certificate asserts + between an identity and a key. This can include checking various + aspects of the certificate's construction, such as verifying the + digital signature on the certificate by performing calculations, + verifying that the current time is within the certificate's + validity period, and validating a certification path involving + additional certificates. + + The word "verify" derives from a Latin word that means "true". + Thus, to verify means to check the truth of an assertion by + examining evidence or performing tests. For example, to verify an + identity, an authentication process examines identification + information that is presented or generated. To validate a + certificate, a certificate user verifies the digital signature on + the certificate by performing calculations, verifies that the + + + +Shirey Informational [Page 331] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + current time is within the certificate's validity period, and may + need to validate a certification path involving additional + certificates. + + $ validation + (I) See: validate vs. verify. + + $ validity period + (I) /PKI/ A data item in a digital certificate that specifies the + time period for which the binding between data items (especially + between the subject name and the public key value in a public-key + certificate) is valid, except if the certificate appears on a CRL + or the key appears on a CKL. (See: cryptoperiod, key lifetime.) + + $ value-added network (VAN) + (I) A computer network or subnetwork (usually a commercial + enterprise) that transmits, receives, and stores EDI transactions + on behalf of its users. + + Tutorial: A VAN may also provide additional services, ranging from + EDI format translation, to EDI-to-FAX conversion, to integrated + business systems. + + $ VAN + (I) See: value-added network. + + $ verification + 1. (I) /authentication/ The process of examining information to + establish the truth of a claimed fact or value. (See: validate vs. + verify, verify. Compare: authentication.) + + 2. (N) /COMPUSEC/ The process of comparing two levels of system + specification for proper correspondence, such as comparing a + security model with a top-level specification, a top-level + specification with source code, or source code with object code. + [NCS04] + + $ verified design + (O) See: TCSEC Class A1. + + $ verify + (I) To test or prove the truth or accuracy of a fact or value. + (See: validate vs. verify, verification. Compare: authenticate.) + + $ vet + (I) /verb/ To examine or evaluate thoroughly. (Compare: + authenticate, identity proofing, validate, verify.) + + + + +Shirey Informational [Page 332] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ violation + See: security violation. + + $ virtual private network (VPN) + (I) A restricted-use, logical (i.e., artificial or simulated) + computer network that is constructed from the system resources of + a relatively public, physical (i.e., real) network (e.g., the + Internet), often by using encryption (located at hosts or + gateways), and often by tunneling links of the virtual network + across the real network. (See: tunnel.) + + Tutorial: A VPN is generally less expensive to build and operate + than a dedicated real network, because the virtual network shares + the cost of system resources with other users of the underlying + real network. For example, if a corporation has LANs at several + different sites, each connected to the Internet by a firewall, the + corporation could create a VPN by using encrypted tunnels to + connect from firewall to firewall across the Internet. + + $ virus + (I) A self-replicating (and usually hidden) section of computer + software (usually malicious logic) that propagates by infecting -- + i.e., inserting a copy of itself into and becoming part of -- + another program. A virus cannot run by itself; it requires that + its host program be run to make the virus active. + + $ Visa Cash + (O) A smartcard-based electronic money system that incorporates + cryptography and can be used to make payments via the Internet. + (See: IOTP.) + + $ volatile media + (I) Storage media that require an external power supply to + maintain stored information. (Compare: non-volatile media, + permanent storage.) + + $ VPN + (I) See: virtual private network. + + $ vulnerability + (I) A flaw or weakness in a system's design, implementation, or + operation and management that could be exploited to violate the + system's security policy. (See: harden.) + + Tutorial: A system can have three types of vulnerabilities: (a) + vulnerabilities in design or specification; (b) vulnerabilities in + implementation; and (c) vulnerabilities in operation and + management. Most systems have one or more vulnerabilities, but + + + +Shirey Informational [Page 333] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + this does not mean that the systems are too flawed to use. Not + every threat results in an attack, and not every attack succeeds. + Success depends on the degree of vulnerability, the strength of + attacks, and the effectiveness of any countermeasures in use. If + the attacks needed to exploit a vulnerability are very difficult + to carry out, then the vulnerability may be tolerable. If the + perceived benefit to an attacker is small, then even an easily + exploited vulnerability may be tolerable. However, if the attacks + are well understood and easily made, and if the vulnerable system + is employed by a wide range of users, then it is likely that there + will be enough motivation for someone to launch an attack. + + $ W3 + (D) Synonym for WWW. + + Deprecated Abbreviation: This abbreviation could be confused with + W3C; use "WWW" instead. + + $ W3C + (N) See: World Wide Web Consortium. + + $ war dialer + (I) /slang/ A computer program that automatically dials a series + of telephone numbers to find lines connected to computer systems, + and catalogs those numbers so that a cracker can try to break the + systems. + + Deprecated Usage: IDOCs that use this term SHOULD state a + definition for it because the term could confuse international + readers. + + $ Wassenaar Arrangement + (N) The Wassenaar Arrangement on Export Controls for Conventional + Arms and Dual-Use Goods and Technologies is a global, multilateral + agreement approved by 33 countries in July 1996 to contribute to + regional and international security and stability, by promoting + information exchange concerning, and greater responsibility in, + transfers of arms and dual-use items, thus preventing + destabilizing accumulations. (See: International Traffic in Arms + Regulations.) + + Tutorial: The Arrangement began operations in September 1996 with + headquarters in Vienna. The participating countries were + Argentina, Australia, Austria, Belgium, Bulgaria, Canada, Czech + Republic, Denmark, Finland, France, Germany, Greece, Hungary, + Ireland, Italy, Japan, Luxembourg, Netherlands, New Zealand, + Norway, Poland, Portugal, Republic of Korea, Romania, Russian + + + + +Shirey Informational [Page 334] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Federation, Slovak Republic, Spain, Sweden, Switzerland, Turkey, + Ukraine, United Kingdom, and United States. + + Participating countries seek through their national policies to + ensure that transfers do not contribute to the development or + enhancement of military capabilities that undermine the goals of + the arrangement, and are not diverted to support such + capabilities. The countries maintain effective export controls for + items on the agreed lists, which are reviewed periodically to + account for technological developments and experience gained. + Through transparency and exchange of views and information, + suppliers of arms and dual-use items can develop common + understandings of the risks associated with their transfer and + assess the scope for coordinating national control policies to + combat these risks. Members provide semi-annual notification of + arms transfers, covering seven categories derived from the UN + Register of Conventional Arms. Members also report transfers or + denials of transfers of certain controlled dual-use items. + However, the decision to transfer or deny transfer of any item is + the sole responsibility of each participating country. All + measures undertaken with respect to the arrangement are in + accordance with national legislation and policies and are + implemented on the basis of national discretion. + + $ watermarking + See: digital watermarking. + + $ weak key + (I) In the context of a particular cryptographic algorithm, a key + value that provides poor security. (See: strong.) + + Example: The DEA has four "weak keys" [Schn] for which encryption + produces the same result as decryption. It also has ten pairs of + "semi-weak keys" [Schn] (a.k.a. "dual keys" [FP074]) for which + encryption with one key in the pair produces the same result as + decryption with the other key. + + $ web, Web + 1. (I) /not capitalized/ IDOCs SHOULD NOT capitalize "web" when + using the term (usually as an adjective) to refer generically to + technology -- such as web browsers, web servers, HTTP, and HTML -- + that is used in the Web or similar networks. + + 2. (I) /capitalized/ IDOCs SHOULD capitalize "Web" when using the + term (as either a noun or an adjective) to refer specifically to + the World Wide Web. (Similarly, see: internet.) + + + + + +Shirey Informational [Page 335] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Usage: IDOCs SHOULD NOT use "web" or "Web" in a way that might + confuse these definitions with the PGP "web of trust". When using + Web as an abbreviation for "World Wide Web", IDOCs SHOULD fully + spell out the term at the first instance of usage. + + $ web of trust + (D) /PGP/ A PKI architecture in which each certificate user + defines their own trust anchor(s) by depending on personal + relationships. (See: trust anchor. Compare: hierarchical PKI, mesh + PKI.) + + Deprecated Usage: IDOCs SHOULD NOT use this term except with + reference to PGP. This term mixes concepts in potentially + misleading ways; e.g., this architecture does not depend on World + Wide Web technology. Instead of this term, IDOCs MAY use "trust- + file PKI". (See: web, Web). + + Tutorial: This type of architecture does not usually include + public repositories of certificates. Instead, each certificate + user builds their own, private repository of trusted public keys + by making personal judgments about being able to trust certain + people to be holding properly certified keys of other people. It + is this set of person-to-person relationships from which the + architecture gets its name. + + $ web server + (I) A software process that runs on a host computer connected to a + network and responds to HTTP requests made by client web browsers. + + $ WEP + (N) See: Wired Equivalency Protocol. + + $ Wired Equivalent Privacy (WEP) + (N) A cryptographic protocol that is defined in the IEEE 802.11 + standard and encapsulates the packets on wireless LANs. Usage: + a.k.a. "Wired Equivalency Protocol". + + Tutorial: The WEP design, which uses RC4 to encrypt both the plain + text and a CRC, has been shown to be flawed in multiple ways; and + it also has often suffered from flawed implementation and + management. + + $ wiretapping + (I) An attack that intercepts and accesses information contained + in a data flow in a communication system. (See: active + wiretapping, end-to-end encryption, passive wiretapping, secondary + definition under "interception".) + + + + +Shirey Informational [Page 336] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Usage: Although the term originally referred to making a + mechanical connection to an electrical conductor that links two + nodes, it is now used to refer to accessing information from any + sort of medium used for a link or even from a node, such as a + gateway or subnetwork switch. + + Tutorial: Wiretapping can be characterized according to intent: + - "Active wiretapping" attempts to alter the data or otherwise + affect the flow. + - "Passive wiretapping" only attempts to observe the data flow + and gain knowledge of information contained in it. + + $ work factor + 1a. (I) /COMPUSEC/ The estimated amount of effort or time that can + be expected to be expended by a potential intruder to penetrate a + system, or defeat a particular countermeasure, when using + specified amounts of expertise and resources. (See: brute force, + impossible, strength.) + + 1b. (I) /cryptography/ The estimated amount of computing power and + time needed to break a cryptographic system. (See: brute force, + impossible, strength.) + + $ World Wide Web ("the Web", WWW) + (N) The global, hypermedia-based collection of information and + services that is available on Internet servers and is accessed by + browsers using Hypertext Transfer Protocol and other information + retrieval mechanisms. (See: web vs. Web, [R2084].) + + $ World Wide Web Consortium (W3C) + (N) Created in October 1994 to develop and standardize protocols + to promote the evolution and interoperability of the Web, and now + consisting of hundreds of member organizations (commercial firms, + governmental agencies, schools, and others). + + Tutorial: W3C Recommendations are developed through a process + similar to that of the standards published by other organizations, + such as the IETF. The W3 Recommendation Track (i.e., standards + track) has four levels of increasing maturity: Working, Candidate + Recommendation, Proposed Recommendation, and W3C Recommendation. + W3C Recommendations are similar to the standards published by + other organizations. (Compare: Internet Standard, ISO.) + + $ worm + (I) A computer program that can run independently, can propagate a + complete working version of itself onto other hosts on a network, + and may consume system resources destructively. (See: mobile code, + Morris Worm, virus.) + + + +Shirey Informational [Page 337] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + $ wrap + 1. (N) To use cryptography to provide data confidentiality service + for keying material. (See: encrypt, wrapping algorithm, wrapping + key. Compare: seal, shroud.) + + 2. (D) To use cryptography to provide data confidentiality service + for data in general. + + Deprecated Usage: IDOCs SHOULD NOT use this term with definition 2 + because that duplicates the meaning of the more widely understood + "encrypt". + + $ wrapping algorithm + (N) An encryption algorithm that is specifically intended for use + in encrypting keys. (See: KEK, wrap.) + + $ wrapping key + (N) Synonym for "KEK". (See: encrypt. Compare: seal, shroud.) + + $ write + (I) /security model/ A system operation that causes a flow of + information from a subject to an object. (See: access mode. + Compare: read.) + + $ WWW + (I) See: World Wide Web. + + $ X.400 + (N) An ITU-T Recommendation [X400] that is one part of a joint + ITU-T/ISO multi-part standard (X.400-X.421) that defines the + Message Handling Systems. (The ISO equivalent is IS 10021, parts + 1-7.) (See: Message Handling Systems.) + + $ X.500 + (N) An ITU-T Recommendation [X500] that is one part of a joint + ITU-T/ISO multi-part standard (X.500-X.525) that defines the X.500 + Directory, a conceptual collection of systems that provide + distributed directory capabilities for OSI entities, processes, + applications, and services. (The ISO equivalent is IS 9594-1 and + related standards, IS 9594-x.) (See: directory vs. Directory, + X.509.) + + Tutorial: The X.500 Directory is structured as a tree (the + Directory Information Tree), and information is stored in + directory entries. Each entry is a collection of information about + one object, and each object has a DN. A directory entry is + composed of attributes, each with a type and one or more values. + For example, if a PKI uses the Directory to distribute + + + +Shirey Informational [Page 338] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + certificates, then the X.509 public-key certificate of an end user + is normally stored as a value of an attribute of type + "userCertificate" in the Directory entry that has the DN that is + the subject of the certificate. + + $ X.509 + (N) An ITU-T Recommendation [X509] that defines a framework to + provide and support data origin authentication and peer entity + authentication, including formats for X.509 public-key + certificates, X.509 attribute certificates, and X.509 CRLs. (The + ISO equivalent is IS 9498-4.) (See: X.500.) + + Tutorial: X.509 describes two "levels" of authentication: "simple + authentication" and "strong authentication". It recommends, "While + simple authentication offers some limited protection against + unauthorized access, only strong authentication should be used as + the basis for providing secure services." + + $ X.509 attribute certificate + (N) An attribute certificate in the version 1 (v1) format defined + by X.509. (The v1 designation for an X.509 attribute certificate + is disjoint from the v1 designation for an X.509 public-key + certificate, and from the v1 designation for an X.509 CRL.) + + Tutorial: An X.509 attribute certificate has a "subject" field, + but the attribute certificate is a separate data structure from + that subject's public-key certificate. A subject may have multiple + attribute certificates associated with each of its public-key + certificates, and an attribute certificate may be issued by a + different CA than the one that issued the associated public-key + certificate. + + An X.509 attribute certificate contains a sequence of data items + and has a digital signature that is computed from that sequence. + Besides the signature, an attribute certificate contains items 1 + through 9 listed below: + + 1. version Identifies v1. + 2. subject Is one of the following: + 2a. baseCertificateID Issuer and serial number of an + X.509 public-key certificate. + 2b. subjectName DN of the subject. + 3. issuer DN of the issuer (the CA who signed). + 4. signature OID of algorithm that signed the cert. + 5. serialNumber Certificate serial number; + an integer assigned by the issuer. + 6. attCertValidityPeriod Validity period; a pair of UTCTime + values: "not before" and "not after". + + + +Shirey Informational [Page 339] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + 7. attributes Sequence of attributes describing the + subject. + 8. issuerUniqueId Optional, when a DN is not sufficient. + 9. extensions Optional. + + $ X.509 certificate + (N) Synonym for "X.509 public-key certificate". + + Usage: IDOCs MAY use this term as an abbreviation of "X.509 + public-key certificate", but only after using the full term at the + first instance. Otherwise, the term is ambiguous, because X.509 + specifies both public-key certificates and attribute certificates. + (See: X.509 attribute certificate, X.509 public-key certificate.) + + Deprecated Usage: IDOCs SHOULD NOT use this term as an + abbreviation of "X.509 attribute certificate", because the term is + much more commonly used to mean "X.509 public-key certificate" + and, therefore, is likely to be misunderstood. + + $ X.509 certificate revocation list (CRL) + (N) A CRL in one of the formats defined by X.509 -- version 1 (v1) + or version 2 (v2). (The v1 and v2 designations for an X.509 CRL + are disjoint from the v1 and v2 designations for an X.509 public- + key certificate, and from the v1 designation for an X.509 + attribute certificate.) (See: certificate revocation.) + + Usage: IDOCs SHOULD NOT refer to an X.509 CRL as a digital + certificate; however, note that an X.509 CRL does meet this + Glossary's definition of "digital certificate". That is, like a + digital certificate, an X.509 CRL makes an assertion and is signed + by a CA. But instead of binding a key or other attributes to a + subject, an X.509 CRL asserts that certain previously issued, + X.509 certificates have been revoked. + + Tutorial: An X.509 CRL contains a sequence of data items and has a + digital signature computed on that sequence. Besides the + signature, both v1 and v2 contain items 2 through 6b listed below. + Version 2 contains item 1 and may optionally contain 6c and 7. + + 1. version Optional. If present, identifies v2. + 2. signature OID of the algorithm that signed CRL. + 3. issuer DN of the issuer (the CA who signed). + 4. thisUpdate A UTCTime value. + 5. nextUpdate A UTCTime value. + 6. revokedCertificates 3-tuples of 6a, 6b, and (optional) 6c: + 6a. userCertificate A certificate's serial number. + 6b. revocationDate UTCTime value for the revocation date. + 6c. crlEntryExtensions Optional. + + + +Shirey Informational [Page 340] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + 7. crlExtensions Optional. + + $ X.509 public-key certificate + (N) A public-key certificate in one of the formats defined by + X.509 -- version 1 (v1), version 2 (v2), or version 3 (v3). (The + v1 and v2 designations for an X.509 public-key certificate are + disjoint from the v1 and v2 designations for an X.509 CRL, and + from the v1 designation for an X.509 attribute certificate.) + + Tutorial: An X.509 public-key certificate contains a sequence of + data items and has a digital signature computed on that sequence. + Besides the signature, all three versions contain items 1 through + 7 listed below. Only v2 and v3 certificates may also contain items + 8 and 9, and only v3 may contain item 10. + + 1. version Identifies v1, v2, or v3. + 2. serialNumber Certificate serial number; + an integer assigned by the issuer. + 3. signature OID of algorithm that was used to + sign the certificate. + 4. issuer DN of the issuer (the CA who signed). + 5. validity Validity period; a pair of UTCTime + values: "not before" and "not after". + 6. subject DN of entity who owns the public key. + 7. subjectPublicKeyInfo Public key value and algorithm OID. + 8. issuerUniqueIdentifier Defined for v2, v3; optional. + 9. subjectUniqueIdentifier Defined for v2, v2; optional. + 10. extensions Defined only for v3; optional. + + $ X9 + (N) See: "Accredited Standards Committee X9" under "ANSI". + + $ XML + (N) See: Extensible Markup Language. + + $ XML-Signature. + (N) A W3C Recommendation (i.e., approved standard) that specifies + XML syntax and processing rules for creating and representing + digital signatures (based on asymmetric cryptography) that can be + applied to any digital content (i.e., any data object) including + other XML material. + + $ Yellow Book + (D) /slang/ Synonym for "Computer Security Requirements: Guidance + for Applying the [U.S.] Department of Defense Trusted Computer + System Evaluation Criteria in Specific Environments" [CSC3] (See: + "first law" under "Courtney's laws".) + + + + +Shirey Informational [Page 341] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + Deprecated Term: IDOCs SHOULD NOT use this term as a synonym for + that or any other document. Instead, use the full proper name of + the document or, in subsequent references, a conventional + abbreviation. (See: Deprecated Usage under "Green Book", Rainbow + Series.) + + $ zero-knowledge proof + (I) /cryptography/ A proof-of-possession protocol whereby a system + entity can prove possession of some information to another entity, + without revealing any of that information. (See: proof-of- + possession protocol.) + + $ zeroize + 1. (I) Synonym for "erase". (See: sanitize.) Usage: Particularly + with regard to erasing keys that are stored in a cryptographic + module. + + 2. (O) Erase electronically stored data by altering the contents + of the data storage so as to prevent the recovery of the data. + [FP140] + + 3. (O) "To remove or eliminate the key from a cryptoequipment or + fill device." [C4009] + + Usage: The phrase "zeroize the device" normally is used to mean + erasing all keys stored in the device, but sometimes means erasing + all keying material in the device, or all cryptographic + information in the device, or even all sensitive information in + the device. + + $ zombie + (I) /slang/ An Internet host computer that has been + surreptitiously penetrated by an intruder that installed malicious + daemon software to cause the host to operate as an accomplice in + attacking other hosts, particularly in distributed attacks that + attempt denial of service through flooding. + + Deprecated Usage: Other cultures likely use different metaphorical + terms (such as "robot") for this concept, and some use this term + for different concepts. Therefore, to avoid international + misunderstanding, IDOCs SHOULD NOT use this term. Instead, use + "compromised, coopted computer" or other explicitly descriptive + terminology. (See: Deprecated Usage under "Green Book".) + + $ zone of control + (O) /EMSEC/ Synonym for "inspectable space". [C4009] (See: + TEMPEST.) + + + + +Shirey Informational [Page 342] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + +5. Security Considerations + + This document mainly defines security terms and recommends how to use + them. It also provides limited tutorial information about security + aspects of Internet protocols, but it does not describe in detail the + vulnerabilities of, or threats to, specific protocols and does not + definitively describe mechanisms that protect specific protocols. + +6. Normative Reference + + [R2119] Bradner, S., "Key words for use in RFCs to Indicate + Requirement Levels", BCP 14, RFC 2119, March 1997. + +7. Informative References + + This Glossary focuses on the Internet Standards Process. Therefore, + this set of informative references emphasizes international, + governmental, and industrial standards documents. Some RFCs that are + especially relevant to Internet security are mentioned in Glossary + entries in square brackets (e.g., "[R1457]" in the entry for + "security label") and are listed here; some other RFCs are mentioned + in parentheses (e.g., "(RFC 959)" in the entry for "File Transport + Protocol") but are not listed here. + + [A1523] American National Standards Institute, "American National + Standard Telecom Glossary", ANSI T1.523-2001. + + [A3092] ---, "American National Standard Data Encryption Algorithm", + ANSI X3.92-1981, 30 December 1980. + + [A9009] ---, "Financial Institution Message Authentication + (Wholesale)", ANSI X9.9-1986, 15 August 1986. + + [A9017] ---, "Financial Institution Key Management (Wholesale)", + X9.17, 4 April 1985. (Defines procedures for manual and + automated management of keying material and uses DES to + provide key management for a variety of operational + environments.) + + [A9042] ---, "Public key Cryptography for the Financial Service + Industry: Agreement of Symmetric Keys Using Diffie-Hellman + and MQV Algorithms", X9.42, 29 January 1999. (See: Diffie- + Hellman-Merkle.) + + [A9052] ---, "Triple Data Encryption Algorithm Modes of Operation", + X9.52-1998, ANSI approval 9 November 1998. + + + + + +Shirey Informational [Page 343] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + [A9062] ---, "Public Key Cryptography for the Financial Services + Industry: The Elliptic Curve Digital Signature Algorithm + (ECDSA)", X9.62-1998, ANSI approval 7 January 1999. + + [A9063] ---, "Public Key Cryptography for the Financial Services + Industry: Key Agreement and Key Transport Using Elliptic + Curve Cryptography", X9.63-2001. + + [ACM] Association for Computing Machinery, "Communications of the + ACM", July 1998 issue with: M. Yeung, "Digital + Watermarking"; N. Memom and P. Wong, "Protecting Digital + Media Content"; and S. Craver, B.-L. Yeo, and M. Yeung, + "Technical Trials and Legal Tribulations". + + [Ande] Anderson, J., "Computer Security Technology Planning Study", + ESD-TR-73-51, Vols. I and II, USAF Electronics Systems Div., + Bedford, MA, October 1972. (Available as AD-758206/772806, + National Technical Information Service, Springfield, VA.) + + [ANSI] American National Standards Institute, "Role Based Access + Control", Secretariat, Information Technology Industry + Council, BSR INCITS 359, DRAFT, 10 November 2003. + + [Army] U.S. Army Corps of Engineers, "Electromagnetic Pulse (EMP) + and Tempest Protection for Facilities", EP 1110-3-2, 31 + December 1990. + + [B1822] Bolt Baranek and Newman Inc., "Appendix H: Interfacing a + Host to a Private Line Interface", in "Specifications for + the Interconnection of a Host and an IMP", BBN Report No. + 1822, revised, December 1983. + + [B4799] ---, "A History of the Arpanet: The First Decade", BBN + Report No. 4799, April 1981. + + [Bell] Bell, D. and L. LaPadula, "Secure Computer Systems: + Mathematical Foundations and Model", M74-244, The MITRE + Corporation, Bedford, MA, May 1973. (Available as AD-771543, + National Technical Information Service, Springfield, VA.) + + [Biba] K. Biba, "Integrity Considerations for Secure Computer + Systems", ESD-TR-76-372, USAF Electronic Systems Division, + Bedford, MA, April 1977. + + [BN89] Brewer, D. and M. Nash, "The Chinese wall security policy", + in "Proceedings of IEEE Symposium on Security and Privacy", + May 1989, pp. 205-214. + + + + +Shirey Informational [Page 344] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + [BS7799] British Standards Institution, "Information Security + Management, Part 1: Code of Practice for Information + Security Management", BS 7799-1:1999, 15 May 1999. + + ---, "Information Security Management, Part 2: Specification + for Information Security Management Systems", BS 7799- + 2:1999, 15 May 1999. + + [C4009] Committee on National Security Systems (U.S. Government), + "National Information Assurance (IA) Glossary", CNSS + Instruction No. 4009, revised June 2006. + + [CCIB] Common Criteria Implementation Board, "Common Criteria for + Information Technology Security Evaluation, Part 1: + Introduction and General Model", version 2.0, CCIB-98-026, + May 1998. + + [Chau] D. Chaum, "Untraceable Electronic Mail, Return Addresses, + and Digital Pseudonyms", in "Communications of the ACM", + vol. 24, no. 2, February 1981, pp. 84-88. + + [Cheh] Cheheyl, M., Gasser, M., Huff, G., and J. Millen, "Verifying + Security", in "ACM Computing Surveys", vol. 13, no. 3, + September 1981, pp. 279-339. + + [Chris] Chrissis, M. et al, 1993. "SW-CMM [Capability Maturity Model + for Software Version", Release 3.0, Software Engineering + Institute, Carnegie Mellon University, August 1996. + + [CIPSO] Trusted Systems Interoperability Working Group, "Common IP + Security Option", version 2.3, 9 March 1993. + + [Clark] Clark, D. and D. Wilson, "A Comparison of Commercial and + Military computer Security Policies", in "Proceedings of the + IEEE Symposium on Security and Privacy", April 1987, pp. + 184-194. + + [Cons] NSA, "Consistency Instruction Manual for Development of U.S. + Government Protection Profiles for Use in Basic Robustness + Environments", Release 2.0, 1 March 2004 + + [CORBA] Object Management Group, Inc., "CORBAservices: Common Object + Service Specification", December 1998. + + [CSC1] U.S. DoD Computer Security Center, "Department of Defense + Trusted Computer System Evaluation Criteria", CSC-STD-001- + 83, 15 August 1983. (Superseded by [DoD1].) + + + + +Shirey Informational [Page 345] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + [CSC2] ---, "Department of Defense Password Management Guideline", + CSC-STD-002-85, 12 April 1985. + + [CSC3] ---, "Computer Security Requirements: Guidance for Applying + the Department of Defense Trusted Computer System Evaluation + Criteria in Specific Environments", CSC-STD-003-85, 25 June + 1985. + + [CSOR] U.S. Department of Commerce, "General Procedures for + Registering Computer Security Objects", National Institute + of Standards Interagency Report 5308, December 1993. + + [Daem] Daemen, J. and V. Rijmen, "Rijndael, the advanced encryption + standard", in "Dr. Dobb's Journal", vol. 26, no. 3, March + 2001, pp. 137-139. + + [DC6/9] Director of Central Intelligence, "Physical Security + Standards for Sensitive Compartmented Information + Facilities", DCI Directive 6/9, 18 November 2002. + + [Denn] Denning, D., "A Lattice Model of Secure Information Flow", + in "Communications of the ACM", vol. 19, no. 5, May 1976, + pp. 236-243. + + [Denns] Denning, D. and P. Denning, "Data Security", in "ACM + Computing Surveys", vol. 11, no. 3, September 1979, pp. 227- + 249. + + [DH76] Diffie, W. and M. Hellman, "New Directions in Cryptography", + in "IEEE Transactions on Information Theory", vol. IT-22, + no. 6, November 1976, pp. 644-654. (See: Diffie-Hellman- + Merkle.) + + [DoD1] U.S. DoD, "Department of Defense Trusted Computer System + Evaluation Criteria", DoD 5200.28-STD, 26 December 1985. + (Supersedes [CSC1].) (Superseded by DoD Directive 8500.1.) + + [DoD4] ---, "NSA Key Recovery Assessment Criteria", 8 June 1998. + + [DoD5] ---, Directive 5200.1, "DoD Information Security Program", + 13 December 1996. + + [DoD6] ---, "Department of Defense Technical Architecture Framework + for Information Management, Volume 6: Department of Defense + (DoD) Goal Security Architecture", Defense Information + Systems Agency, Center for Standards, version 3.0, 15 April + 1996. + + + + +Shirey Informational [Page 346] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + [DoD7] ---, "X.509 Certificate Policy for the United States + Department of Defense", version 7, 18 December 2002. + (Superseded by [DoD9].) + + [DoD9] ---, "X.509 Certificate Policy for the United States + Department of Defense", version 9, 9 February 2005. + + [DoD10] ---, "DoD Architecture Framework, Version 1: Deskbook", 9 + February 2004. + + [DSG] American Bar Association, "Digital Signature Guidelines: + Legal Infrastructure for Certification Authorities and + Secure Electronic Commerce", Chicago, IL, 1 August 1996. + (See: [PAG].) + + [ElGa] El Gamal, T., "A Public-Key Cryptosystem and a Signature + Scheme Based on Discrete Logarithms", in "IEEE Transactions + on Information Theory", vol. IT-31, no. 4, 1985, pp. 469- + 472. + + [EMV1] Europay International S.A., MasterCard International + Incorporated, and Visa International Service Association, + "EMV '96 Integrated Circuit Card Specification for Payment + Systems", version 3.1.1, 31 May 1998. + + [EMV2] ---, "EMV '96 Integrated Circuit Card Terminal Specification + for Payment Systems", version 3.1.1, 31 May 1998. + + [EMV3] ---, "EMV '96 Integrated Circuit Card Application + Specification for Payment Systems", version 3.1.1, 31 May + 1998. + + [F1037] U.S. General Services Administration, "Glossary of + Telecommunications Terms", FED STD 1037C, 7 August 1996. + + [For94] Ford, W., "Computer Communications Security: Principles, + Standard Protocols and Techniques", ISBN 0-13-799453-2, + 1994. + + [For97] --- and M. Baum, "Secure Electronic Commerce: Building the + Infrastructure for Digital Signatures and Encryption", ISBN + 0-13-476342-4, 1994. + + [FP001] U.S. Department of Commerce, "Code for Information + Interchange", Federal Information Processing Standards + Publication (FIPS PUB) 1, 1 November 1968. + + + + + +Shirey Informational [Page 347] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + [FP031] ---, "Guidelines for Automatic Data Processing Physical + Security and Risk Management", FIPS PUB 31, June 1974. + + [FP039] ---, "Glossary for Computer Systems Security", FIPS PUB 39, + 15 February 1976. + + [FP041] ---, "Computer Security Guidelines for Implementing the + Privacy Act of 1974", FIPS PUB 41, 30 May 1975. + + [FP046] ---, "Data Encryption Standard (DES)", FIPS PUB 46-3, 25 + October 1999. + + [FP074] ---, "Data Encryption Standard (DES)", FIPS PUB 46-3, 25 + October 1999. + + [FP081] ---, "DES Modes of Operation", FIPS PUB 81, 2 December 1980. + + [FP087] ---, "Guidelines for ADP Contingency Planning", FIPS PUB 87, + 27 March 1981. + + [FP102] ---, "Guideline for Computer Security Certification and + Accreditation", FIPS PUB 102, 27 September 1983. + + [FP113] ---, "Computer Data Authentication", FIPS PUB 113, 30 May + 1985. + + [FP140] ---, "Security Requirements for Cryptographic Modules", FIPS + PUB 140-2, 25 May 2001; with change notice 4, 3 December + 2002. + + [FP151] ---, "Portable Operating System Interface (POSIX) -- System + Application Program Interface [C Language]", FIPS PUB 151-2, + 12 May 1993 + + [FP180] ---, "Secure Hash Standard", FIPS PUB 180-2, August 2000; + with change notice 1, 25 February 2004. + + [FP185] ---, "Escrowed Encryption Standard", FIPS PUB 185, 9 + February 1994. + + [FP186] ---, "Digital Signature Standard (DSS)", FIPS PUB 186-2, 27 + June 2000; with change notice 1, 5 October 2001. + + [FP188] ---, "Standard Security Label for Information Transfer", + FIPS PUB 188, 6 September 1994. + + [FP191] ---, "Guideline for the Analysis of Local Area Network + Security", FIPS PUB 191, 9 November 1994. + + + +Shirey Informational [Page 348] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + [FP197] ---, "Advanced Encryption Standard", FIPS PUB 197, 26 + November 2001. + + [FP199] ---, "Standards for Security Categorization of Federal + Information and Information Systems ", FIPS PUB 199, + December 2003. + + [FPKI] ---, "Public Key Infrastructure (PKI) Technical + Specifications: Part A -- Technical Concept of Operations", + NIST, 4 September 1998. + + [Gass] Gasser, M., "Building a Secure Computer System", Van + Nostrand Reinhold Company, New York, 1988, ISBN 0-442- + 23022-2. + + [Gray] Gray, J. and A. Reuter, "Transaction Processing: Concepts + and Techniques", Morgan Kaufmann Publishers, Inc., 1993. + + [Hafn] Hafner, K. and M. Lyon, "Where Wizards Stay Up Late: The + Origins of the Internet", Simon & Schuster, New York, 1996. + + [Huff] Huff, G., "Trusted Computer Systems -- Glossary", MTR 8201, + The MITRE Corporation, March 1981. + + [I3166] International Standards Organization, "Codes for the + Representation of Names of Countries and Their Subdivisions, + Part 1: Country Codes", ISO 3166-1:1997. + + ---, "Codes for the Representation of Names of Countries and + Their Subdivisions, Part 2: Country Subdivision Codes", + ISO/DIS 3166-2. + + ---, "Codes for the Representation of Names of Countries and + Their Subdivisions, Part 3: Codes for Formerly Used Names of + Countries", ISO/DIS 3166-3. + + [I7498-1] ---, "Information Processing Systems -- Open Systems + Interconnection Reference Model, [Part 1:] Basic Reference + Model", ISO/IEC 7498-1. (Equivalent to ITU-T Recommendation + X.200.) + + [I7498-2] ---, "Information Processing Systems -- Open Systems + Interconnection Reference Model, Part 2: Security + Architecture", ISO/IEC 7499-2. + + [I7498-4] ---, "Information Processing Systems -- Open Systems + Interconnection Reference Model, Part 4: Management + Framework", ISO/IEC 7498-4. + + + +Shirey Informational [Page 349] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + [I7812] ---, "Identification cards -- Identification of Issuers, + Part 1: Numbering System", ISO/IEC 7812-1:1993 + + ---, "Identification cards -- Identification of Issuers, + Part 2: Application and Registration Procedures", ISO/IEC + 7812-2:1993. + + [I8073] ---, "Information Processing Systems -- Open Systems + Interconnection, Transport Protocol Specification", ISO IS + 8073. + + [I8327] ---, "Information Processing Systems -- Open Systems + Interconnection, Session Protocol Specification", ISO IS + 8327. + + [I8473] ---, "Information Processing Systems -- Open Systems + Interconnection, Protocol for Providing the Connectionless + Network Service", ISO IS 8473. + + [I8802-2] ---, "Information Processing Systems -- Local Area + Networks, Part 2: Logical Link Control", ISO IS 8802-2. + (Equivalent to IEEE 802.2.) + + [I8802-3] ---, "Information Processing Systems -- Local Area + Networks, Part 3: Carrier Sense Multiple Access with + Collision Detection (CSMA/CD) Access Method and Physical + Layer Specifications", ISO IS 8802-3. (Equivalent to IEEE + 802.3.) + + [I8823] ---, "Information Processing Systems -- Open Systems + Interconnection -- Connection-Oriented Presentation Protocol + Specification", ISO IS 8823. + + [I9945] "Portable Operating System Interface for Computer + Environments", ISO/IEC 9945-1: 1990. + + [IATF] NSA, "Information Assurance Technical Framework", Release 3, + NSA, September 2000. (See: IATF.) + + [IDSAN] ---, "Intrusion Detection System Analyzer Protection + Profile", version 1.1, NSA, 10 December 2001. + + [IDSSC] ---, "Intrusion Detection System Scanner Protection + Profile", version 1.1, NSA, 10 December 2001. + + [IDSSE] ---, "Intrusion Detection System Sensor Protection Profile", + version 1.1, NSA, 10 December 2001. + + + + +Shirey Informational [Page 350] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + [IDSSY] ---, "Intrusion Detection System", version 1.4, NSA, 4 + February 2002. + + [Ioan] Ioannidis, J. and M. Blaze, "The Architecture and + Implementation of Network Layer Security in UNIX", in "UNIX + Security IV Symposium", October 1993, pp. 29-39. + + [ITSEC] "Information Technology Security Evaluation Criteria + (ITSEC): Harmonised Criteria of France, Germany, the + Netherlands, and the United Kingdom", version 1.2, U.K. + Department of Trade and Industry, June 1991. + + [JP1] U.S. DoD, "Department of Defense Dictionary of Military and + Associated Terms", Joint Publication 1-02, as amended + through 13 June 2007. + + [John] Johnson, N. and S. Jajodia, "Exploring Steganography; Seeing + the Unseen", in "IEEE Computer", February 1998, pp. 26-34. + + [Kahn] Kahn, D., "The Codebreakers: The Story of Secret Writing", + The Macmillan Company, New York, 1967. + + [Knut] Knuth, D., Chapter 3 ("Random Numbers") of Volume 2 + ("Seminumerical Algorithms") of "The Art of Computer + Programming", Addison-Wesley, Reading, MA, 1969. + + [Kuhn] Kuhn, M. and R. Anderson, "Soft Tempest: Hidden Data + Transmission Using Electromagnetic Emanations", in David + Aucsmith, ed., "Information Hiding, Second International + Workshop, IH'98", Portland, Oregon, USA, 15-17 April 1998, + LNCS 1525, Springer-Verlag, ISBN 3-540-65386-4, pp. 124-142. + + [Land] Landwehr, C., "Formal Models for Computer Security", in "ACM + Computing Surveys", vol. 13, no. 3, September 1981, pp. 247- + 278. + + [Larm] Larmouth, J., "ASN.1 Complete", Open System Solutions, 1999 + (a freeware book). + + [M0404] U.S. Office of Management and Budget, "E-Authentication + Guidance for Federal Agencies", Memorandum M-04-04, 16 + December 2003. + + [Mene] Menezes, A. et al, "Some Key Agreement Protocols Providing + Implicit Authentication", in "The 2nd Workshop on Selected + Areas in Cryptography", 1995. + + + + + +Shirey Informational [Page 351] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + [Moor] Moore, A. et al, "Attack Modeling for Information Security + and Survivability", Carnegie Mellon University / Software + Engineering Institute, CMU/SEI-2001-TN-001, March 2001. + + [Murr] Murray, W., "Courtney's Laws of Security", in "Infosecurity + News", March/April 1993, p. 65. + + [N4001] National Security Telecommunications and Information System + Security Committee, "Controlled Cryptographic Items", + NSTISSI No. 4001, 25 March 1985. + + [N4006] ---, "Controlled Cryptographic Items", NSTISSI No. 4006, 2 + December 1991. + + [N7003] ---, "Protective Distribution Systems", NSTISSI No. 7003, 13 + December 1996. + + [NCS01] National Computer Security Center, "A Guide to Understanding + Audit in Trusted Systems", NCSC-TG-001, 1 June 1988. (See: + Rainbow Series.) + + [NCS03] ---, "Information System Security Policy Guideline", I942- + TR-003, version 1, July 1994. (See: Rainbow Series.) + + [NCS04] ---, "Glossary of Computer Security Terms", NCSC-TG-004, + version 1, 21 October 1988. (See: Rainbow Series.) + + [NCS05] ---, "Trusted Network Interpretation of the Trusted Computer + System Evaluation Criteria", NCSC-TG-005, version 1, 31 July + 1987. (See: Rainbow Series.) + + [NCS25] ---, "A Guide to Understanding Data Remanence in Automated + Information Systems", NCSC-TG-025, version 2, September + 1991. (See: Rainbow Series.) + + [NCSSG] National Computer Security Center, "COMPUSECese: Computer + Security Glossary", NCSC-WA-001-85, Edition 1, 1 October + 1985. (See: Rainbow Series.) + + [NRC91] National Research Council, "Computers At Risk: Safe + Computing in the Information Age", National Academy Press, + 1991. + + [NRC98] Schneider, F., ed., "Trust in Cyberspace", National Research + Council, National Academy of Sciences, 1998. + + [Padl] Padlipsky, M., "The Elements of Networking Style", 1985, + ISBN 0-13-268111-0. + + + +Shirey Informational [Page 352] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + [PAG] American Bar Association, "PKI Assessment Guidelines", + version 1.0, 10 May 2002. (See: [DSG].) + + [Park] Parker, D., "Computer Security Management", ISBN 0-8359- + 0905-0, 1981 + + [Perr] Perrine, T. et al, "An Overview of the Kernelized Secure + Operating System (KSOS)", in "Proceedings of the 7th DoD/NBS + Computer Security Conference", 24-26 September 1984. + + [PGP] Garfinkel, S.. "PGP: Pretty Good Privacy", O'Reilly & + Associates, Inc., Sebastopol, CA, 1995. + + [PKCS] Kaliski Jr., B., "An Overview of the PKCS Standards", RSA + Data Security, Inc., 3 June 1991. + + [PKC05] RSA Laboratories, "PKCS #5: Password-Based Encryption + Standard ", version 1.5, 1 November 1993. (See: RFC 2898.) + + [PKC07] ---, "PKCS #7: Cryptographic Message Syntax Standard", + version 1.5, 1 November 1993. (See: RFC 2315.) + + [PKC10] ---, "PKCS #10: Certification Request Syntax Standard", + version 1.0, 1 November 1993. + + [PKC11] ---, "PKCS #11: Cryptographic Token Interface Standard", + version 1.0, 28 April 1995. + + [PKC12] ---, "PKCS #12: Personal Information Exchange Syntax", + version 1.0, 24 June 1995. + + [R1108] Kent, S., "U.S. Department of Defense Security Options for + the Internet Protocol", RFC 1108, November 1991. + + [R1135] Reynolds, J., "The Helminthiasis of the Internet", RFC 1135, + December 1989 + + [R1208] Jacobsen, O. and D. Lynch, "A Glossary of Networking Terms", + RFC 1208, March 1991. + + [R1281] Pethia, R., Crocker, S., and B. Fraser, "Guidelines for + Secure Operation of the Internet", RFC 1281, November 1991. + + [R1319] Kaliski, B., "The MD2 Message-Digest Algorithm", RFC 1319, + April 1992. + + [R1320] Rivest, R., "The MD4 Message-Digest Algorithm", RFC 1320, + April 1992. + + + +Shirey Informational [Page 353] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + [R1321] ---, "The MD5 Message-Digest Algorithm", RFC 1321, April + 1992. + + [R1334] Lloyd, B. and W. Simpson, "PPP Authentication Protocols", + RFC 1334, October 1992. + + [R1413] St. Johns, M., "Identification Protocol", RFC 1413, February + 1993. + + [R1421] Linn, J., "Privacy Enhancement for Internet Electronic Mail, + Part I: Message Encryption and Authentication Procedures", + RFC 1421, February 1993. + + [R1422] Kent, S., "Privacy Enhancement for Internet Electronic Mail, + Part II: Certificate-Based Key Management", RFC 1422, + February 1993. + + [R1455] Eastlake 3rd, D., "Physical Link Security Type of Service", + RFC 1455, May 1993. + + [R1457] Housley, R., "Security Label Framework for the Internet", + RFC 1457, May 1993. + + [R1492] Finseth, C., "An Access Control Protocol, Sometimes Called + TACACS", RFC 1492, July 1993. + + [R1507] Kaufman, C., "DASS: Distributed Authentication Security + Service", RFC 1507, September 1993. + + [R1731] Myers, J., "IMAP4 Authentication Mechanisms", RFC 1731, + December 1994. + + [R1734] ---, "POP3 AUTHentication Command", RFC 1734, Dec, 1994. + + [R1760] Haller, N., "The S/KEY One-Time Password System", RFC 1760, + February 1995. + + [R1824] Danisch, H., "The Exponential Security System TESS: An + Identity-Based Cryptographic Protocol for Authenticated Key- + Exchange (E.I.S.S.-Report 1995/4)", RFC 1824, August 1995. + + [R1828] Metzger, P. and W. Simpson, "IP Authentication using Keyed + MD5", RFC 1828, August 1995. + + [R1829] Karn, P., Metzger, P., and W. Simpson, "The ESP DES-CBC + Transform", RFC 1829, August 1995. + + + + + +Shirey Informational [Page 354] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + [R1848] Crocker, S., Freed, N., Galvin, J., and S. Murphy, "MIME + Object Security Services", RFC 1848, October 1995. + + [R1851] Karn, P., Metzger, P., and W. Simpson, "The ESP Triple DES + Transform", RFC 1851, September 1995. + + [R1928] Leech, M., Ganis, M., Lee, Y., Kuris, R., Koblas, D., and L. + Jones, "SOCKS Protocol Version 5", RFC 1928, March 1996. + + [R1958] Carpenter, B., "Architectural Principles of the Internet", + RFC 1958, June 1996. + + [R1983] Malkin, G., "Internet Users' Glossary", FYI 18, RFC 1983, + August 1996. + + [R1994] Simpson, W., "PPP Challenge Handshake Authentication + Protocol (CHAP)", RFC 1994, August 1996. + + [R2078] Linn, J., "Generic Security Service Application Program + Interface, Version 2", RFC 2078, January 1997. (Superseded + by RFC 2743.) + + [R2084] Bossert, G., Cooper, S., and W. Drummond, "Considerations + for Web Transaction Security", RFC 2084, January 1997. + + [R2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed- + Hashing for Message Authentication", RFC 2104, February + 1997. + + [R2144] Adams, C., "The CAST-128 Encryption Algorithm", RFC 2144, + May 1997. + + [R2179] Gwinn, A., "Network Security For Trade Shows", RFC 2179, + July 1997. + + [R2195] Klensin, J., Catoe, R., and P. Krumviede, "IMAP/POP + AUTHorize Extension for Simple Challenge/Response", RFC + 2195, September 1997. + + [R2196] Fraser, B., "Site Security Handbook", FYI 8, RFC 2196, + September 1997. + + [R2202] Cheng, P. and R. Glenn, "Test Cases for HMAC-MD5 and HMAC- + SHA-1", RFC 2202, Sep. 1997. + + [R2222] Myers, J., "Simple Authentication and Security Layer + (SASL)", RFC 2222, October 1997. + + + + +Shirey Informational [Page 355] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + [R2289] Haller, N., Metz, C., Nesser, P., and M. Straw, "A One-Time + Password System", STD 61, RFC 2289, February 1998. + + [R2323] Ramos, A., "IETF Identification and Security Guidelines", + RFC 2323, 1 April 1998. (Intended for humorous entertainment + -- "please laugh loud and hard" -- and does not contain + serious security information.) + + [R2350] Brownlee, N. and E. Guttman, "Expectations for Computer + Security Incident Response", BCP 21, RFC 2350, June 1998. + + [R2356] Montenegro, G. and V. Gupta, "Sun's SKIP Firewall Traversal + for Mobile IP", RFC 2356, June 1998. + + [R2401] Kent, S. and R. Atkinson, "Security Architecture for the + Internet Protocol", RFC 2401, November 1998. + + [R2402] ---, "IP Authentication Header", RFC 2402, November 1998. + + [R2403] Madson, C. and R. Glenn, "The Use of HMAC-MD5-96 within ESP + and AH", RFC 2403, November 1998. + + [R2404] ---, "The Use of HMAC-SHA-1-96 within ESP and AH", RFC 2404, + November 1998. + + [R2405] Madson, C. and N. Doraswamy, "The ESP DES-CBC Cipher + Algorithm With Explicit IV", RFC 2405, November 1998. + + [R2406] Kent, S. and R. Atkinson, "IP Encapsulating Security Payload + (ESP)", RFC 2406, November 1998. + + [R2407] Piper, D. "The Internet IP Security Domain of Interpretation + for ISAKMP", RFC 2407, November 1998. + + [R2408] Maughan, D., Schertler, M., Schneider, M., and J. Turner, + "Internet Security Association and Key Management Protocol + (ISAKMP)", RFC 2408, November 1998. + + [R2410] Glenn, R. and S. Kent, "The NULL Encryption Algorithm and + Its Use With IPsec", RFC 2410, November 1998. + + [R2412] Orman, H., "The OAKLEY Key Determination Protocol", RFC + 2412, November 1998. + + [R2451] Pereira, R. and R. Adams, "The ESP CBC-Mode Cipher + Algorithms", RFC 2451, November 1998. + + + + + +Shirey Informational [Page 356] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + [R2504] Guttman, E., Leong, L., and G. Malkin, "Users' Security + Handbook", RFC 2504, February 1999. + + [R2560] Myers, M., Ankney, R., Malpani, A., Galperin, S., and C. + Adams, "X.509 Internet Public Key Infrastructure Online + Certificate Status Protocol - OCSP", RFC 2560, June 1999. + + [R2612] Adams, C. and J. Gilchrist, "The CAST-256 Encryption + Algorithm", RFC 2612, June 1999. + + [R2628] Smyslov, V., "Simple Cryptographic Program Interface (Crypto + API)", RFC 2628, June 1999. + + [R2631] Rescorla, E., "Diffie-Hellman Key Agreement Method", RFC + 2631, June 1999. (See: Diffie-Hellman-Merkle.) + + [R2634] Hoffman, P., "Enhanced Security Services for S/MIME", RFC + 2634, June 1999. + + [R2635] Hambridge, S. and A. Lunde, "DON'T SPEW: A Set of Guidelines + for Mass Unsolicited Mailings and Postings", RFC 2635, June + 1999. + + [R2660] Rescorla, E. and A. Schiffman, "The Secure HyperText + Transfer Protocol", RFC 2660, August 1999. + + [R2743] Linn, J., "Generic Security Service Application Program + Interface Version 2, Update 1", RFC 2743, January 2000. + + [R2773] Housley, R., Yee, P., and W. Nace, "Encryption using KEA and + SKIPJACK", RFC 2773, February 2000. + + [R2801] Burdett, D., "Internet Open Trading Protocol - IOTP, Version + 1.0", RFC 2801, April 2000. + + [R2827] Ferguson, P. and D. Senie, "Network Ingress Filtering: + Defeating Denial of Service Attacks which employ IP Source + Address Spoofing", BCP 38, RFC 2827, May 2000. + + [R2865] Rigney, C., Willens, S., Rubens, A., and W. Simpson, "Remote + Authentication Dial In User Service (RADIUS)", RFC 2865, + June 2000. + + [R3060] Moore, B., Ellesson, E., Strassner, J., and A. Westerinen, + "Policy Core Information Model -- Version 1 Specification", + RFC 3060, February 2001. + + + + + +Shirey Informational [Page 357] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + [R3198] Westerinen, A., Schnizlein, J., Strassner, J., Scherling, + M., Quinn, B., Herzog, S., Huynh, A., Carlson, M., Perry, + J., and S. Waldbusser, "Terminology for Policy-Based + Management", RFC 3198, November 2001. + + [R3280] Housley, R., Polk, W., Ford, W., and D. Solo, "Internet + X.509 Public Key Infrastructure Certificate and Certificate + Revocation List (CRL) Profile", RFC 3280, April 2002. + + [R3547] Baugher, M., Weis, B., Hardjono, T., and H. Harney, "Group + Domain of Interpretation", RFC 3547, July 2003. + + [R3552] Rescorla, E. and B. Korver, "Guidelines for Writing RFC Text + on Security Considerations", RFC 3552, July 2003. + + [R3647] Chokhani, S., Ford, W., Sabett, R., Merrill, C., and S. Wu, + "Internet X.509 Public Key Infrastructure Certificate Policy + and Certification Practices Framework", RFC 3647, November + 2003. + + [R3739] Santesson, S., Nystrom, M., and T. Polk, "Internet X.509 + Public Key Infrastructure: Qualified Certificates Profile", + RFC 3739, March 2004. + + [R3740] Hardjono, T. and B. Weis, "The Multicast Group Security + Architecture", RFC 3740, March 2004. + + [R3748] Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H. + Levkowetz, "Extensible Authentication Protocol (EAP)", RFC + 3748, June 2004. + + [R3766] Orman, H. and P. Hoffman, "Determining Strengths For Public + Keys Used For Exchanging Symmetric Keys", BCP 86, RFC 3766, + April 2004. + + [R3820] Tuecke, S., Welch, V., Engert, D., Pearlman, L., and M. + Thompson, "Internet X.509 Public Key Infrastructure (PKI) + Proxy Certificate Profile", RFC 3820, June 2004. + + [R3851] Ramsdell, B., "Secure/Multipurpose Internet Mail Extensions + (S/MIME) Version 3.1 Message Specification", RFC 3851, July + 2004. + + [R3871] Jones, G., "Operational Security Requirements for Large + Internet Service Provider (ISP) IP Network Infrastructure", + RFC 3871, September 2004. + + + + + +Shirey Informational [Page 358] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + [R4033] Arends, R., Austein, R., Larson, M., Massey, D., and S. + Rose, "DNS Security Introduction and Requirements", RFC + 4033, March 2005. + + [R4034] Arends, R., Austein, R., Larson, M., Massey, D., and S. + Rose, "Resource Records for the DNS Security Extensions", + RFC 4034, March 2005. + + [R4035] Arends, R., Austein, R., Larson, M., Massey, D., and S. + Rose, "Protocol Modifications for the DNS Security + Extensions", RFC 4035, March 2005. + + [R4086] Eastlake, D., 3rd, Schiller, J., and S. Crocker, "Randomness + Requirements for Security", BCP 106, RFC 4086, June 2005. + + [R4120] Neuman, C., Yu, T., Hartman, S., and K. Raeburn, "The + Kerberos Network Authentication Service (V5)", RFC 4120, + July 2005. + + [R4158] Cooper, M., Dzambasow, Y., Hesse, P., Joseph, S., and R. + Nicholas, "Internet X.509 Public Key Infrastructure: + Certification Path Building", RFC 4158, September 2005. + + [R4210] Adams, C., Farrell, S., Kause, T., and T. Mononen, "Internet + X.509 Public Key Infrastructure Certificate Management + Protocol (CMP)", RFC 4210, September 2005. + + [R4301] Kent, S. and K. Seo, "Security Architecture for the Internet + Protocol", RFC 4301, December 2005. + + [R4302] Kent, S., "IP Authentication Header", RFC 4302, December + 2005. + + [R4303] Kent, S., "IP Encapsulating Security Payload (ESP)", RFC + 4303, December 2005. + + [R4306] Kaufman, C., "Internet Key Exchange (IKEv2) Protocol", RFC + 4306, December 2005. + + [R4346] Dierks, T. and E. Rescorla, "The Transport Layer Security + (TLS) Protocol Version 1.1", RFC 4346, April 2006. + + [R4422] Melnikov, A. and K. Zeilenga, "Simple Authentication and + Security Layer (SASL)", RFC 4422, June 2006. + + + + + + + +Shirey Informational [Page 359] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + [Raym] Raymond, E., ed., "The On-Line Hacker Jargon File", version + 4.0.0, 24 July 1996. (See: http://www.catb.org/~esr/jargon + for the latest version. Also, "The New Hacker's Dictionary", + 3rd edition, MIT Press, September 1996, ISBN 0-262-68092-0.) + + [Roge] Rogers, H., "An Overview of the CANEWARE Program", in + "Proceedings of the 10th National Computer Security + Conference", NIST and NCSC, September 1987. + + [RSA78] Rivest, R., A. Shamir, and L. Adleman, "A Method for + Obtaining Digital Signatures and Public-Key Cryptosystems", + in "Communications of the ACM", vol. 21, no. 2, February + 1978, pp. 120-126. + + [RSCG] NSA, "Router Security Configuration Guide: Principles and + Guidance for Secure Configuration of IP Routers, with + Detailed Instructions for Cisco Systems Routers", version + 1.1c, C4-040R-02, 15 December 2005, available at + http://www.nsa.gov/snac/routers/C4-040R-02.pdf. + + [Russ] Russell, D. et al, Chapter 10 ("TEMPEST") of "Computer + Security Basics", ISBN 0-937175-71-4, 1991. + + [SAML] Organization for the Advancement of Structured Information + Standards (OASIS), "Assertions and Protocol for the OASIS + Security Assertion Markup Language (SAML)", version 1.1, 2 + September 2003. + + [Sand] Sandhu, R. et al, "Role-Based Access Control Models", in + "IEEE Computer", vol. 29, no. 2, February 1996, pp. 38-47. + + [Schn] Schneier, B., "Applied Cryptography Second Edition", John + Wiley & Sons, Inc., New York, 1996. + + [SDNS3] U.S. DoD, NSA, "Secure Data Network Systems, Security + Protocol 3 (SP3)", document SDN.301, Revision 1.5, 15 May + 1989. + + [SDNS4] ---, "Secure Data Network Systems, Security Protocol 4 + (SP4)", document SDN.401, Revision 1.2, 12 July 1988. + + [SDNS7] ---, "Secure Data Network Systems, Message Security Protocol + (MSP)", SDN.701, Revision 4.0, 7 June 1996, with + "Corrections to Message Security Protocol, SDN.701, Rev 4.0, + 96-06-07", 30 Aug, 1996. + + + + + + +Shirey Informational [Page 360] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + [SET1] MasterCard and Visa, "SET Secure Electronic Transaction + Specification, Book 1: Business Description", version 1.0, + 31 May 1997. + + [SET2] ---, "SET Secure Electronic Transaction Specification, Book + 2: Programmer's Guide", version 1.0, 31 May 1997. + + [SKEME] Krawczyk, H., "SKEME: A Versatile Secure Key Exchange + Mechanism for Internet", in "Proceedings of the 1996 + Symposium on Network and Distributed Systems Security". + + [SKIP] "SKIPJACK and KEA Algorithm Specifications", version 2.0, 22 + May 1998, and "Clarification to the SKIPJACK Algorithm + Specification", 9 May 2002 (available from NIST Computer + Security Resource Center). + + [SP12] NIST, "An Introduction to Computer Security: The NIST + Handbook", Special Publication 800-12. + + [SP14] Swanson, M. et al (NIST), "Generally Accepted Principles and + Practices for Security Information Technology Systems", + Special Publication 800-14, September 1996. + + [SP15] Burr, W. et al (NIST), "Minimum Interoperability + Specification for PKI Components (MISPC), Version 1", + Special Publication 800-15, September 1997. + + [SP22] Rukhin, A. et al (NIST), "A Statistical Test Suite for + Random and Pseudorandom Number Generators for Cryptographic + Applications", Special Publication 800-15, 15 May 2001. + + [SP27] Stoneburner, G. et al (NIST), "Engineering Principles for + Information Technology Security (A Baseline for Achieving + Security)", Special Publication 800-27 Rev A, June 2004. + + [SP28] Jansen, W. (NIST), "Guidelines on Active Content and Mobile + Code", Special Publication 800-28, October 2001. + + [SP30] Stoneburner, G. et al (NIST), "Risk Management Guide for + Information Technology Systems", Special Publication 800-30, + October 2001. + + [SP31] Bace, R. et al (NIST), "Intrusion Detection Systems", + Special Publication 800-31. + + [SP32] Kuhn, D. (NIST), "Introduction to Public Key Technology and + the Federal PKI Infrastructure ", Special Publication + 800-32, 26 February 2001. + + + +Shirey Informational [Page 361] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + [SP33] Stoneburner, G. (NIST), "Underlying Technical Models for + Information Technology Security", Special Publication + 800-33, December 2001. + + [SP37] Ross, R. et al (NIST), "Guide for the Security Certification + and Accreditation of Federal Information Systems", Special + Publication 800-37, May 2004. + + [SP38A] Dworkin, M. (NIST), "Recommendation for Block Cipher Modes + of Operation: Methods and Techniques", Special Publication + 800-38A, 2001 Edition, December 2001. + + [SP38B] ---, "Recommendation for Block Cipher Modes of Operation: + The CMAC Mode for Authentication", Special Publication + 800-38B, May 2005. + + [SP38C] ---, "Recommendation for Block Cipher Modes of Operation: + The CCM Mode for Authentication and Confidentiality", + Special Publication 800-38C, May 2004. + + [SP41] Wack, J. et al (NIST), "Guidelines on Firewalls and Firewall + Policy", Special Publication 800-41, January 2002. + + [SP42] ---, "Guideline on Network Security Testing", Special + Publication 800-42, October 2003. + + [SP56] NIST, "Recommendations on Key Establishment Schemes", Draft + 2.0, Special Publication 800-63, January 2003. + + [SP57] ---, "Recommendation for Key Management", Part 1 "General + Guideline" and Part 2 "Best Practices for Key Management + Organization", Special Publication 800-57, DRAFT, January + 2003. + + [SP61] Grance, T. et al (NIST), "Computer Security Incident + Handling Guide", Special Publication 800-57, January 2003. + + [SP63] Burr, W. et al (NIST), "Electronic Authentication + Guideline", Special Publication 800-63, June 2004 + + [SP67] Barker, W. (NIST), "Recommendation for the Triple Data + Encryption Algorithm (TDEA) Block Cipher", Special + Publication 800-67, May 2004 + + [Stal] Stallings, W., "Local Networks", 1987, ISBN 0-02-415520-9. + + + + + + +Shirey Informational [Page 362] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + [Stei] Steiner, J. et al, "Kerberos: An Authentication Service for + Open Network Systems", in "Usenix Conference Proceedings", + February 1988. + + [Weis] Weissman, C., "Blacker: Security for the DDN: Examples of A1 + Security Engineering Trades", in "Symposium on Security and + Privacy", IEEE Computer Society Press, May 1992, pp. 286- + 292. + + [X400] International Telecommunications Union -- Telecommunication + Standardization Sector (formerly "CCITT"), Recommendation + X.400, "Message Handling Services: Message Handling System + and Service Overview". + + [X419] ---, "Message Handling Systems: Protocol Specifications", + ITU-T Recommendation X.419. (Equivalent to ISO 10021-6). + + [X420] ---, "Message Handling Systems: Interpersonal Messaging + System", ITU-T Recommendation X.420. (Equivalent to ISO + 10021-7.). + + [X500] ---, Recommendation X.500, "Information Technology -- Open + Systems Interconnection -- The Directory: Overview of + Concepts, Models, and Services". (Equivalent to ISO 9594-1.) + + [X501] ---, Recommendation X.501, "Information Technology -- Open + Systems Interconnection -- The Directory: Models". + + [X509] ---, Recommendation X.509, "Information Technology -- Open + Systems Interconnection -- The Directory: Authentication + Framework", COM 7-250-E Revision 1, 23 February 2001. + (Equivalent to ISO 9594-8.) + + [X519] ---, Recommendation X.519, "Information Technology -- Open + Systems Interconnection -- The Directory: Protocol + Specifications". + + [X520] ---, Recommendation X.520, "Information Technology -- Open + Systems Interconnection -- The Directory: Selected Attribute + Types". + + [X680] ---, Recommendation X.680, "Information Technology -- + Abstract Syntax Notation One (ASN.1) -- Specification of + Basic Notation", 15 November 1994. (Equivalent to ISO/IEC + 8824-1.) + + + + + + +Shirey Informational [Page 363] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + + [X690] ---, Recommendation X.690, "Information Technology -- ASN.1 + Encoding Rules -- Specification of Basic Encoding Rules + (BER), Canonical Encoding Rules (CER) and Distinguished + Encoding Rules (DER)", 15 November 1994. (Equivalent to + ISO/IEC 8825-1.) + +7. Acknowledgments + + George Huff had a good idea! [Huff] + +Author's Address + + Dr. Robert W. Shirey + 3516 N. Kensington St. + Arlington, Virginia 22207-1328 + USA + + EMail: rwshirey4949@verizon.net + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +Shirey Informational [Page 364] + +RFC 4949 Internet Security Glossary, Version 2 August 2007 + + +Full Copyright Statement + + Copyright (C) The IETF Trust (2007). + + This document is subject to the rights, licenses and restrictions + contained in BCP 78 and at www.rfc-editor.org/copyright.html, and + except as set forth therein, the authors retain all their rights. + + This document and the information contained herein are provided on an + "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS + OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND + THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS + OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF + THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED + WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. + +Intellectual Property + + The IETF takes no position regarding the validity or scope of any + Intellectual Property Rights or other rights that might be claimed to + pertain to the implementation or use of the technology described in + this document or the extent to which any license under such rights + might or might not be available; nor does it represent that it has + made any independent effort to identify any such rights. Information + on the procedures with respect to rights in RFC documents can be + found in BCP 78 and BCP 79. + + Copies of IPR disclosures made to the IETF Secretariat and any + assurances of licenses to be made available, or the result of an + attempt made to obtain a general license or permission for the use of + such proprietary rights by implementers or users of this + specification can be obtained from the IETF on-line IPR repository at + http://www.ietf.org/ipr. + + The IETF invites any interested party to bring to its attention any + copyrights, patents or patent applications, or other proprietary + rights that may cover technology that may be required to implement + this standard. Please address the information to the IETF at + ietf-ipr@ietf.org. + +Acknowledgement + + Funding for the RFC Editor function is currently provided by the + Internet Society. + + + + + + + +Shirey Informational [Page 365] + |