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+Network Working Group                                          R. Shirey
+Request for Comments: 2828                        GTE / BBN Technologies
+FYI: 36                                                         May 2000
+Category: Informational
+
+
+                       Internet Security Glossary
+
+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 Internet Society (2000).  All Rights Reserved.
+
+Abstract
+
+   This Glossary (191 pages of definitions and 13 pages of references)
+   provides abbreviations, explanations, and recommendations for use of
+   information system security terminology. The intent is to improve the
+   comprehensibility of writing that deals with Internet security,
+   particularly Internet Standards documents (ISDs). To avoid confusion,
+   ISDs should use the same term or definition whenever the same concept
+   is mentioned. To improve international understanding, ISDs should use
+   terms in their plainest, dictionary sense. ISDs should use terms
+   established in standards documents and other well-founded
+   publications and should avoid substituting private or newly made-up
+   terms. ISDs should avoid terms that are proprietary or otherwise
+   favor a particular vendor, or that create a bias toward a particular
+   security technology or mechanism versus other, competing techniques
+   that already exist or might be developed in the future.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Shirey                       Informational                      [Page 1]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+Table of Contents
+
+   1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . .   2
+   2. Explanation of Paragraph Markings  . . . . . . . . . . . . . .   4
+      2.1 Recommended Terms with an Internet Basis ("I") . . . . . .   4
+      2.2 Recommended Terms with a Non-Internet Basis ("N")  . . . .   5
+      2.3 Other Definitions ("O")  . . . . . . . . . . . . . . . . .   5
+      2.4 Deprecated Terms, Definitions, and Uses ("D")  . . . . . .   6
+      2.5 Commentary and Additional Guidance ("C") . . . . . . . . .   6
+   3. Definitions  . . . . . . . . . . . . . . . . . . . . . . . . .   6
+   4. References . . . . . . . . . . . . . . . . . . . . . . . . . . 197
+   5. Security Considerations  . . . . . . . . . . . . . . . . . . . 211
+   6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 211
+   7. Author's Address . . . . . . . . . . . . . . . . . . . . . . . 211
+   8. Full Copyright Statement . . . . . . . . . . . . . . . . . . . 212
+
+1. Introduction
+
+   This Glossary provides an internally consistent, complementary set of
+   abbreviations, definitions, explanations, and recommendations for use
+   of terminology related to information system security. The intent of
+   this Glossary is to improve the comprehensibility of Internet
+   Standards documents (ISDs)--i.e., RFCs, Internet-Drafts, and other
+   material produced as part of the Internet Standards Process [R2026]--
+   and of all other Internet material, too. Some non-security terms are
+   included to make the Glossary self-contained, but more complete lists
+   of networking terms are available elsewhere [R1208, R1983].
+
+   Some glossaries (e.g., [Raym]) list terms that are not listed here
+   but could be applied to Internet security. However, those terms have
+   not been included in this Glossary because they are not appropriate
+   for ISDs.
+
+   This Glossary marks terms and definitions as being either endorsed or
+   deprecated for use in ISDs, but this Glossary is not an Internet
+   standard. The key words "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
+   and "OPTIONAL" are intended to be interpreted the same way as in an
+   Internet Standard [R2119], but this guidance represents only the
+   recommendations of this author. However, this Glossary includes
+   reasons for the recommendations--particularly for the SHOULD NOTs--so
+   that readers can judge for themselves whether to follow the
+   recommendations.
+
+
+
+
+
+
+
+
+
+Shirey                       Informational                      [Page 2]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   This Glossary supports the goals of the Internet Standards Process:
+
+   o Clear, Concise, and Easily Understood Documentation
+
+      This Glossary seeks to improve comprehensibility of security-
+      related content of ISDs. 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, the
+      terminology needs to be uniform across all ISDs; i.e., the same
+      term or definition needs to be used whenever and wherever the same
+      concept is mentioned. Harmonization of existing ISDs need not be
+      done immediately, but it is desirable to correct and standardize
+      the 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, ISDs should use terminology accurately, precisely,
+      and unambiguously to enable Internet Standards to be implemented
+      correctly.
+
+   o Prior Implementation and Testing
+
+      Just as STD protocols require demonstrated experience and
+      stability before adoption, ISDs need to use well-established
+      language. Using terms in their plainest, dictionary sense (when
+      appropriate) helps to ensure international understanding. ISDs
+      need to avoid using private, made-up terms in place of generally-
+      accepted terms from standards and other publications. ISDs need to
+      avoid substituting new definitions that conflict with established
+      ones. ISDs need to avoid using "cute" synonyms (e.g., see: Green
+      Book); no matter how popular a nickname may be in one community,
+      it is likely to cause confusion in another.
+
+   o Openness, Fairness, and Timeliness
+
+      ISDs need to avoid terms that are proprietary or otherwise favor a
+      particular vendor, or that create a bias toward 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 ISDs needs to be flexible and
+      adaptable as the state of Internet security art evolves.
+
+
+
+
+
+
+
+
+Shirey                       Informational                      [Page 3]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+2. Explanation of Paragraph Markings
+
+   Section 3 marks terms and definitions as follows:
+
+   o Capitalization: Only terms that are proper nouns are capitalized.
+
+   o Paragraph Marking: Definitions and explanations are stated in
+      paragraphs that are marked as follows:
+
+      - "I" identifies a RECOMMENDED Internet definition.
+      - "N" identifies a RECOMMENDED non-Internet definition.
+      - "O" identifies a definition that is not recommended as the first
+        choice for Internet documents but is something that authors of
+        Internet documents need to know.
+      - "D" identifies a term or definition that SHOULD NOT be used in
+        Internet documents.
+      - "C" identifies commentary or additional usage guidance.
+
+   The rest of Section 2 further explains these five markings.
+
+2.1 Recommended Terms with an Internet Basis ("I")
+
+   The paragraph marking "I" (as opposed to "O") indicates a definition
+   that SHOULD be the first choice for use in ISDs. Most terms and
+   definitions of this type MAY be used in ISDs; however, some "I"
+   definitions are accompanied by a "D" paragraph that recommends
+   against using the term. Also, some "I" definitions are preceded by an
+   indication of a contextual usage limitation (e.g., see:
+   certification), and ISDs should not the term and definition outside
+   that context
+
+   An "I" (as opposed to an "N") also indicates that the definition has
+   an Internet basis. That is, either the Internet Standards Process is
+   authoritative for the term, or the term is sufficiently generic that
+   this Glossary can freely state a definition without contradicting a
+   non-Internet authority (e.g., see: attack).
+
+   Many terms with "I" definitions are proper nouns (e.g., see:
+   Internet Protocol). For such terms, the "I" definition is intended
+   only to provide basic information; the authoritative definition is
+   found elsewhere.
+
+   For a proper noun identified as an "Internet protocol", please refer
+   to the current edition of "Internet Official Protocol Standards" (STD
+   1) for the standardization state and status of the protocol.
+
+
+
+
+
+
+Shirey                       Informational                      [Page 4]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+2.2 Recommended Terms with a Non-Internet Basis ("N")
+
+   The paragraph marking "N" (as opposed to "O") indicates a definition
+   that SHOULD be the first choice for the term, if the term is used at
+   all in Internet documents. Terms and definitions of this type MAY be
+   used in Internet documents (e.g., see: X.509 public-key certificate).
+
+   However, an "N" (as opposed to an "I") also indicates a definition
+   that has a non-Internet basis or origin. Many such definitions are
+   preceded by an indication of a contextual usage limitation, and this
+   Glossary's endorsement does not apply outside that context.  Also,
+   some contexts are rarely if ever expected to occur in a Internet
+   document (e.g., see: 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.
+
+   Many terms with "N" definitions are proper nouns (e.g., see:
+   Computer Security Objects Register). For such terms, the "N"
+   definition is intended only to provide basic information; the
+   authoritative definition is found elsewhere.
+
+2.3 Other Definitions ("O")
+
+   The paragraph marking "O" indicates a definition that has a non-
+   Internet basis, but indicates that the definition SHOULD NOT be used
+   in ISDs *except* in cases where the term is specifically identified
+   as non-Internet.
+
+   For example, an ISD might mention "BCA" (see: brand certification
+   authority) or "baggage" as an example to illustrate some concept; in
+   that case, the document should specifically say "SET(trademark) BCA"
+   or "SET(trademark) baggage" and include the definition of the term.
+
+   For some terms that have a definition published by a non-Internet
+   authority--government (see: object reuse), industry (see: Secure Data
+   Exchange), national (see: Data Encryption Standard), or international
+   (see: data confidentiality)--this Glossary marks the definition "N",
+   recommending its use in Internet documents. In other cases, the non-
+   Internet definition of a term is inadequate or inappropriate for
+   ISDs. For example, it may be narrow or outdated, or it may need
+   clarification by substituting more careful or more explanatory
+   wording using other terms that are defined in this Glossary. In those
+   cases, this Glossary marks the tern "O" and provides an "I"
+   definition (or sometimes a different "N" definition), which precedes
+   and supersedes the definition marked "O".
+
+
+
+
+
+
+Shirey                       Informational                      [Page 5]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   In most of the cases where this Glossary provides a definition to
+   supersede one from a non-Internet standard, the substitute is
+   intended to subsume the meaning of the superseded "O" definition 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 OSI model and is inadequate for the full
+   range of ISD usage; the "I" definition can be used in more situations
+   and for more kinds of service. However, the "O" definition is also
+   provided here so that ISD authors will be aware of the context in
+   which the term is used more narrowly.
+
+   When making substitutions, this Glossary attempts to use
+   understandable English that does not contradict any non-Internet
+   authority. Still, terminology differs between the standards of the
+   American Bar Association, OSI, SET, the U.S. Department of Defense,
+   and other authorities, and this Glossary probably is not exactly
+   aligned with all of them.
+
+2.4 Deprecated Terms, Definitions, and Uses ("D")
+
+   If this Glossary recommends that a term or definition SHOULD NOT be
+   used in ISDs, then either the definition has the paragraph marking
+   "D", or the restriction is stated in a "D" paragraph that immediately
+   follows the term or definition.
+
+2.5 Commentary and Additional Guidance ("C")
+
+   The paragraph marking "C" identifies text that is advisory or
+   tutorial. This text MAY be reused in other Internet documents.  This
+   text is not intended to be authoritative, but is provided to clarify
+   the definitions and to enhance this Glossary so that Internet
+   security novices can use it as a tutorial.
+
+3. Definitions
+
+   Note: Each acronym or other abbreviation (except items of common
+   English usage, such as "e.g.", "etc.", "i.e.", "vol.", "pp.", "U.S.")
+   that is used in this Glossary, either in a definition or as a subpart
+   of a defined term, is also defined in this Glossary.
+
+   $ 3DES
+      See: triple DES.
+
+   $ *-property
+      (N) (Pronounced "star property".) See: "confinement property"
+      under Bell-LaPadula Model.
+
+
+
+
+
+Shirey                       Informational                      [Page 6]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ ABA Guidelines
+      (N) "American Bar Association (ABA) Digital Signature Guidelines"
+      [ABA], 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. [X680]
+
+      (C) OSI standards use ASN.1 to specify data formats for protocols.
+      OSI defines functionality in layers. Information objects at higher
+      layers are abstractly defined to be implemented with objects at
+      lower layers. A higher layer may define transfers of abstract
+      objects between computers, and a lower layer may define transfers
+      concretely as strings of bits. Syntax is needed to define abstract
+      objects, and encoding rules are needed to transform between
+      abstract objects and bit strings. (See: Basic Encoding Rules.)
+
+      (C) 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
+      See: access control center.
+
+   $ access
+      (I) The ability and means to communicate with or otherwise
+      interact with a system in order to use system resources to either
+      handle information or gain knowledge of the information the system
+      contains.
+
+      (O) "A specific type of interaction between a subject and an
+      object that results in the flow of information from one to the
+      other." [NCS04]
+
+      (C) In this Glossary, "access" is intended to cover any ability to
+      communicate with a system, including one-way communication in
+      either direction. In actual practice, however, entities outside a
+      security perimeter that can receive output from the system but
+      cannot provide input or otherwise directly interact with the
+      system, might be treated as not having "access" and, therefore, be
+      exempt from security policy requirements, such as the need for a
+      security clearance.
+
+   $ access control
+      (I) Protection of system resources against unauthorized access; a
+      process by which use of system resources is regulated according to
+      a security policy and is permitted by only authorized entities
+
+
+
+Shirey                       Informational                      [Page 7]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (users, programs, processes, or other systems) according to that
+      policy. (See: access, access control service.)
+
+      (O) "The prevention of unauthorized use of a resource, including
+      the prevention of use of a resource in an unauthorized manner."
+      [I7498 Part 2]
+
+   $ access control center (ACC)
+      (I) A computer containing a database with entries that define a
+      security policy for an access control service.
+
+      (C) An ACC is sometimes used in conjunction with a key center to
+      implement access control in a key distribution system for
+      symmetric cryptography.
+
+   $ access control list (ACL)
+      (I) A mechanism that implements access control for a system
+      resource by enumerating the identities of the system entities that
+      are permitted to access the resource. (See: capability.)
+
+   $ 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; in short, protection of system resources against
+      unauthorized access. (See: access control, discretionary access
+      control, identity-based security policy, mandatory access control,
+      rule-based security policy.)
+
+      (C) This service includes protecting against use of a resource in
+      an unauthorized manner by an entity that is authorized to use the
+      resource in some other manner. The two basic mechanisms for
+      implementing this service are ACLs and tickets.
+
+   $ access mode
+      (I) A distinct type of data processing operation--e.g., read,
+      write, append, or execute--that a subject can potentially perform
+      on an object in a computer system.
+
+   $ accountability
+      (I) The property of a system (including all of its system
+      resources) that ensures that the actions of a system entity may be
+      traced uniquely to that entity, which can be held responsible for
+      its actions. (See: audit service.)
+
+      (C) Accountability permits detection and subsequent investigation
+      of security breaches.
+
+
+
+
+
+Shirey                       Informational                      [Page 8]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ accredit
+   $ accreditation
+      (I) An administrative declaration by a designated authority that
+      an information system is approved to operate in a particular
+      security configuration with a prescribed set of safeguards.
+      [FP102] (See: certification.)
+
+      (C) An accreditation is usually based on a technical certification
+      of the system's security mechanisms. The terms "certification" and
+      "accreditation" are used more in the U.S. Department of Defense
+      and other government agencies than in commercial organizations.
+      However, the concepts apply any place where managers are required
+      to deal with and accept responsibility for security risks. The
+      American Bar Association is developing accreditation criteria for
+      CAs.
+
+   $ ACL
+      See: access control list.
+
+   $ acquirer
+      (N) SET usage: "The financial institution that establishes an
+      account with a merchant and processes payment card authorizations
+      and payments." [SET1]
+
+      (O) "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]
+
+   $ active attack
+      See: (secondary definition under) attack.
+
+   $ active wiretapping
+      See: (secondary definition under) wiretapping.
+
+   $ add-on security
+      (I) "The retrofitting of protection mechanisms, implemented by
+      hardware or software, after the [automatic data processing] system
+      has become operational." [FP039]
+
+   $ administrative security
+      (I) Management procedures and constraints to prevent unauthorized
+      access to a system. (See: security architecture.)
+
+      (O) "The management constraints, operational procedures,
+      accountability procedures, and supplemental controls established
+      to provide an acceptable level of protection for sensitive data."
+      [FP039]
+
+
+
+
+Shirey                       Informational                      [Page 9]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (C) Examples include clear delineation and separation of duties,
+      and configuration control.
+
+   $ Advanced Encryption Standard (AES)
+      (N) A future FIPS publication being developed by NIST to succeed
+      DES. Intended to specify an unclassified, publicly-disclosed,
+      symmetric encryption algorithm, available royalty-free worldwide.
+
+   $ adversary
+      (I) An entity that attacks, or is a threat to, a system.
+
+   $ 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 individual items that comprise it.
+
+   $ AH
+      See: Authentication Header
+
+   $ 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 deception.
+
+   $ American National Standards Institute (ANSI)
+      (N) A private, not-for-profit association of users, manufacturers,
+      and other organizations, that administers U.S. private sector
+      voluntary standards.
+
+      (C) ANSI is the sole U.S. representative to the two major non-
+      treaty international standards organizations, ISO and, via the
+      U.S. National Committee (USNC), the International Electrotechnical
+      Commission (IEC).
+
+   $ anonymous
+      (I) The condition of having a name that is unknown or concealed.
+      (See: anonymous login.)
+
+      (C) 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 an account number. Parties to a transaction can thus
+      remain relatively anonymous, but can also accept the transaction
+
+
+
+Shirey                       Informational                     [Page 10]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      as legitimate. Real names of the parties cannot be easily
+      determined by observers of the transaction, 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.
+
+   $ anonymous login
+      (I) An access control feature (or, rather, an access control
+      weakness) in many Internet hosts that enables users to gain access
+      to general-purpose or public services and resources on a host
+      (such as allowing any user to transfer data using File Transfer
+      Protocol) without having a pre-established, user-specific account
+      (i.e., user name and secret password).
+
+      (C) 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.
+
+   $ APOP
+      See: POP3 APOP.
+
+   $ archive
+       (I) (1.) 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. (See: backup.) (2.) Verb: To store data in such
+      a way. (See: back up.)
+
+      (C) 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
+      (N) Advanced Research Projects Agency Network, a pioneer packet-
+      switched network that was built in the early 1970s under contract
+      to the U.S. Government, led to the development of today's
+      Internet, and was decommissioned in June 1990.
+
+
+
+Shirey                       Informational                     [Page 11]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ ASN.1
+      See: Abstract Syntax Notation One.
+
+   $ association
+      (I) A cooperative relationship between system entities, usually
+      for the purpose of transferring information between them. (See:
+      security association.)
+
+   $ assurance
+      (I) (1.) An attribute of an information system that provides
+      grounds for having confidence that the system operates such that
+      the system security policy is enforced. (2.) A procedure that
+      ensures a system is developed and operated as intended by the
+      system's security policy.
+
+   $ assurance level
+      (I) Evaluation usage: A specific level on a hierarchical scale
+      representing successively increased confidence that a target of
+      evaluation adequately fulfills the requirements. (E.g., see:
+      TCSEC.)
+
+   $ asymmetric cryptography
+      (I) A modern branch of cryptography (popularly known as "public-
+      key cryptography") in which the algorithms employ a pair of keys
+      (a public key and a private key) and use a different component of
+      the pair for different steps of the algorithm. (See: key pair.)
+
+      (C) Asymmetric algorithms have key management advantages over
+      equivalently strong symmetric ones. First, one key of the pair
+      does not need to be known by anyone but its owner; so it can more
+      easily be kept secret. Second, although the other key of the pair
+      is shared by all entities that use the algorithm, that key does
+      not need to be kept secret from other, non-using entities; so the
+      key distribution part of key management can be done more easily.
+
+      (C) For encryption: In an asymmetric encryption algorithm (e.g.,
+      see: 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.
+
+      (C) For signature: In an asymmetric digital signature algorithm
+      (e.g., see: 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.
+
+
+
+
+Shirey                       Informational                     [Page 12]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (C) For key agreement: In an asymmetric key agreement algorithm
+      (e.g., see: Diffie-Hellman), Alice and Bob each send their own
+      public key to the other person. Then each uses their own private
+      key and the other's public key to compute the new key value.
+
+   $ attack
+      (I) An assault on system security that derives from an intelligent
+      threat, i.e., an intelligent act that is a deliberate attempt
+      (especially in the sense of a method or technique) to evade
+      security services and violate the security policy of a system.
+      (See: penetration, violation, vulnerability.)
+
+       - Active vs. passive: An "active attack" attempts to alter system
+         resources or affect their operation. A "passive attack"
+         attempts to learn or make use of information from the system
+         but does not affect system resources. (E.g., see: wiretapping.)
+
+       - Insider vs. outsider: An "inside attack" is an attack 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 those who granted the
+         authorization. An "outside attack" is initiated from outside
+         the 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.
+
+      (C) 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  |
+      + - - - - - - - - - - - - +  + - - - - +  + - - - - - - - - - - -+
+
+   $ attribute authority
+      (I) A CA that issues attribute certificates.
+
+      (O) "An authority, trusted by the verifier to delegate privilege,
+      which issues attribute certificates." [FPDAM]
+
+
+
+
+Shirey                       Informational                     [Page 13]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ attribute certificate
+      (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. [X509]
+
+      (O) "A set of attributes of a user together with some other
+      information, rendered unforgeable by the digital signature created
+      using the private key of the CA which issued it." [X509]
+
+      (O) "A data structure that includes some attribute values and
+      identification information about the owner of the attribute
+      certificate, all digitally signed by an Attribute Authority. This
+      authority's signature serves as the guarantee of the binding
+      between the attributes and their owner." [FPDAM]
+
+      (C) A public-key certificate binds a subject name to a public key
+      value, along with information needed to perform certain
+      cryptographic functions. 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.
+
+      (C) 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.)
+
+   $ 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
+      See: security audit trail.
+
+
+
+
+
+
+Shirey                       Informational                     [Page 14]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ AUTH
+      See: POP3 AUTH.
+
+   $ authentic signature
+      (I) A signature (particularly a digital signature) that can be
+      trusted because it can be verified. (See: validate vs. verify.)
+
+   $ authenticate
+      (I) Verify (i.e., establish the truth of) an identity claimed by
+      or for a system entity. (See: authentication.)
+
+      (D) In general English usage, this term usually means "to prove
+      genuine" (e.g., an art expert authenticates a Michelangelo
+      painting). But the recommended definition carries a much narrower
+      meaning. For example, to be precise, an ISD SHOULD NOT say "the
+      host authenticates each received datagram". Instead, the ISD
+      SHOULD say "the host authenticates the origin of each received
+      datagram". In most cases, we also can say "and verifies the
+      datagram's integrity", because that is usually implied. (See:
+      ("relationship between data integrity service and authentication
+      services" under) data integrity service.)
+
+      (D) ISDs SHOULD NOT talk about authenticating a digital signature
+      or digital certificate. Instead, we "sign" and then "verify"
+      digital signatures, and we "issue" and then "validate" digital
+      certificates. (See: validate vs. verify.)
+
+   $ authentication
+      (I) The process of verifying an identity claimed by or for a
+      system entity. (See: authenticate, authentication exchange,
+      authentication information, credential, data origin
+      authentication, peer entity authentication.)
+
+      (C) An authentication process consists of two steps:
+
+      1. Identification step: Presenting an identifier to the security
+         system. (Identifiers should be assigned carefully, because
+         authenticated identities are the basis for other security
+         services, such as access control service.)
+
+      2. Verification step: Presenting or generating authentication
+         information that corroborates the binding between the entity
+         and the identifier. (See: verification.)
+
+      (C) See: ("relationship between data integrity service and
+      authentication services" under) data integrity service.
+
+
+
+
+
+Shirey                       Informational                     [Page 15]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ authentication code
+      (D) ISDs SHOULD NOT use this term as a synonym for any form of
+      checksum, whether cryptographic or not. The word "authentication"
+      is misleading because the mechanism involved usually serves a data
+      integrity function rather than an authentication function, and the
+      word "code" is misleading because it implies that either encoding
+      or encryption is involved or that the term refers to computer
+      software. (See: message authentication code.)
+
+   $ authentication exchange
+      (I) A mechanism to verify the identity of an entity by means of
+      information exchange.
+
+      (O) "A mechanism intended to ensure the identity of an entity by
+      means of information exchange." [I7498 Part 2]
+
+   $ Authentication Header (AH)
+      (I) An Internet IPsec protocol [R2402] designed to provide
+      connectionless data integrity service and data origin
+      authentication service for IP datagrams, and (optionally) to
+      provide protection against replay attacks.
+
+      (C) Replay protection may be selected by the receiver when a
+      security association is established. AH authenticates upper-layer
+      protocol data units and as much of 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.
+
+      (C) AH may be used alone, or in combination with the IPsec ESP
+      protocol, 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 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.)
+
+      (C) Authentication information may exist as, or be derived from,
+      one of the following:
+
+
+
+
+Shirey                       Informational                     [Page 16]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+       - Something the entity knows. (See: password).
+       - Something the entity possesses. (See: token.)
+       - 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.)
+
+      (C) 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) "An entity, responsible for the issuance of certificates."
+      [FPDAM]
+
+      (C) ISDs SHOULD NOT use this term as a synonym for AA, CA, RA,
+      ORA, or similar terms, because it may cause confusion. Instead,
+      use the full term at the first instance of usage and then, if it
+      is necessary to shorten text, use the style of abbreviation
+      defined in this Glossary.
+
+      (C) ISDs SHOULD NOT use this definition for any PKI entity,
+      because the definition is ambiguous with regard to whether the
+      entity actually issues certificates (e.g., attribute authority or
+      certification authority) or just has accountability for processes
+      that precede or follow signing (e.g., registration authority).
+      (See: issue.)
+
+   $ authority certificate
+      (D) "A certificate issued to an authority (e.g. either to a
+      certification authority or to an attribute authority)." [FPDAM]
+      (See: authority.)
+
+      (C) ISDs SHOULD NOT use this term or definition because they are
+      ambiguous with regard to which specific types of PKI entities they
+      address.
+
+   $ authority revocation list (ARL)
+      (I) A data structure that enumerates digital certificates that
+      were issued to CAs but have been invalidated by their issuer prior
+      to when they were scheduled to expire. (See: certificate
+      expiration, X.509 authority revocation list.)
+
+
+
+
+Shirey                       Informational                     [Page 17]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (O) "A revocation list containing a list of public-key
+      certificates issued to authorities, which are no longer considered
+      valid by the certificate issuer." [FPDAM]
+
+   $ authorization
+   $ authorize
+      (I) (1.) An "authorization" is a right or a permission that is
+      granted to a system entity to access a system resource. (2.) An
+      "authorization process" is a procedure for granting such rights.
+      (3.) To "authorize" means to grant such a right or permission.
+      (See: privilege.)
+
+      (O) SET usage: "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]
+
+   $ automated information system
+      (I) An organized assembly of resources and procedures--i.e.,
+      computing and communications equipment and services, with their
+      supporting facilities and personnel--that collect, record,
+      process, store, transport, retrieve, or display information to
+      accomplish a specified set of functions.
+
+   $ availability
+      (I) The property of a system or a system resource being accessible
+      and usable 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,
+      reliability, survivability.)
+
+      (O) "The property of being accessible and usable upon demand by an
+      authorized entity." [I7498 Part 2]
+
+   $ availability service
+      (I) A security service that protects a system to ensure its
+      availability.
+
+      (C) 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.
+
+
+
+Shirey                       Informational                     [Page 18]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ back door
+      (I) A hardware or software mechanism that (a) provides access to a
+      system and its resources by other than the usual procedure, (b)
+      was deliberately left in place by the system's designers or
+      maintainers, and (c) usually is not publicly known. (See: trap
+      door.)
+
+      (C) For example, a way to access a computer other than through a
+      normal login. Such access paths do not necessarily have malicious
+      intent; e.g., operating systems sometimes are shipped by the
+      manufacturer with privileged accounts intended for use by field
+      service technicians or the vendor's maintenance programmers. (See:
+      trap door.)
+
+   $ back up vs. backup
+      (I) Verb "back up": To store data for the purpose of creating a
+      backup copy. (See: archive.)
+
+      (I) Noun/adjective "backup": (1.) A reserve copy of data that is
+      stored separately from the original, for use if the original
+      becomes lost or damaged. (See: archive.) (2.) Alternate means to
+      permit performance of system functions despite a disaster to
+      system resources. (See: contingency plan.)
+
+   $ baggage
+      (D) ISDs SHOULD NOT use this term to describe a data element
+      except when stated as "SET(trademark) baggage" with the following
+      meaning:
+
+      (O) SET usage: 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]
+
+   $ bandwidth
+      (I) Commonly used to mean the capacity of a communication channel
+      to pass data through the channel in a given amount of time.
+      Usually expressed in bits per second.
+
+   $ bank identification number (BIN)
+      (N) The digits of a credit card number that identify the issuing
+      bank. (See: primary account number.)
+
+      (O) SET usage: The first six digits of a primary account number.
+
+
+
+
+
+
+Shirey                       Informational                     [Page 19]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ Basic Encoding Rules (BER)
+      (I) A standard for representing ASN.1 data types as strings of
+      octets. [X690] (See: Distinguished Encoding Rules.)
+
+   $ 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 hosts) in the network that can be directly
+      accessed from networks on the other side of the firewall.
+
+      (C) 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.
+
+   $ BCA
+      See: brand certification authority.
+
+   $ BCI
+      See: brand CRL identifier.
+
+   $ Bell-LaPadula Model
+      (N) A formal, mathematical, state-transition model of security
+      policy for multilevel-secure computer systems. [Bell]
+
+      (C) The model separates computer system elements into a set of
+      subjects and a set of 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.
+
+      (C) In this model, a multilevel-secure system satisfies several
+      rules, including the following:
+
+
+
+
+
+
+
+Shirey                       Informational                     [Page 20]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+       - "Confinement property" (also called "*-property", pronounced
+         "star property"): A subject has write access to an object only
+         if classification of the object dominates the clearance of the
+         subject.
+
+       - "Simple security property": A subject has read access to an
+         object only if the clearance of the subject dominates the
+         classification of the object.
+
+       - "Tranquillity property": The classification of an object does
+         not change while the object is being processed by the system.
+
+   $ BER
+      See: Basic Encoding Rules.
+
+   $ beyond A1
+      (O) (1.) Formally, a level of security assurance that is beyond
+      the highest level of criteria specified by the TCSEC. (2.)
+      Informally, a level of trust so high that it cannot be provided or
+      verified by currently available assurance methods, and
+      particularly not by currently available formal methods.
+
+   $ BIN
+      See: bank identification number.
+
+   $ bind
+      (I) To inseparably associate by applying some mechanism, such as
+      when a CA uses a digital signature to bind together a subject and
+      a public key in a public-key certificate.
+
+   $ biometric authentication
+      (I) A method of generating authentication information for a person
+      by digitizing measurements of a physical characteristic, such as a
+      fingerprint, a hand shape, a retina pattern, a speech pattern
+      (voiceprint), or handwriting.
+
+   $ bit
+      (I) The smallest unit of information storage; a contraction of the
+      term "binary digit"; one of two symbols--"0" (zero) and "1" (one)
+      --that are used to represent binary numbers.
+
+   $ BLACK
+      (I) Designation for information system equipment or facilities
+      that handle (and for data that contains) only ciphertext (or,
+      depending on the context, only unclassified information), and for
+      such data itself. This term derives from U.S. Government COMSEC
+      terminology. (See: RED, RED/BLACK separation.)
+
+
+
+
+Shirey                       Informational                     [Page 21]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ block cipher
+      (I) An encryption algorithm that breaks plaintext into fixed-size
+      segments and uses the same key to transform each plaintext segment
+      into a fixed-size segment of ciphertext. (See: mode, stream
+      cipher.)
+
+      (C) For example, Blowfish, DEA, IDEA, RC2, and SKIPJACK. However,
+      a block cipher can be adapted to have a different external
+      interface, such as that of a stream cipher, by using a mode of
+      operation to "package" the basic algorithm.
+
+   $ 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]
+
+   $ brand
+      (I) A distinctive mark or name that identifies a product or
+      business entity.
+
+      (O) SET usage: The name of a payment card. 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 usage: 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 usage: 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) Cryptographic usage: 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. (This term applies to encrypted
+      data or, more generally, to a cryptographic algorithm or
+      cryptographic system.)
+
+
+
+
+
+
+Shirey                       Informational                     [Page 22]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ bridge
+      (I) A computer that is a gateway between two networks (usually two
+      LANs) at OSI layer 2. (See: router.)
+
+   $ British Standard 7799
+      (N) Part 1 is a standard code of practice and provides guidance on
+      how to secure an information system. Part 2 specifies the
+      management framework, objectives, and control requirements for
+      information security management systems [B7799]. The certification
+      scheme works like ISO 9000. It is in use in the UK, the
+      Netherlands, Australia, and New Zealand and might be proposed as
+      an ISO standard or adapted to be part of the Common Criteria.
+
+   $ browser
+      (I) An client computer program that can retrieve and display
+      information from servers on the World Wide Web.
+
+      (C) For example, Netscape's Navigator and Communicator, and
+      Microsoft's Explorer.
+
+   $ brute force
+      (I) A cryptanalysis technique or other kind of attack method
+      involving an exhaustive procedure that tries all possibilities,
+      one-by-one.
+
+      (C) For example, for ciphertext where the analyst already knows
+      the decryption algorithm, a brute force technique to finding the
+      original plaintext is to decrypt the message with every possible
+      key.
+
+   $ BS7799
+      See: British Standard 7799.
+
+   $ 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.
+      (See: octet.)
+
+      (C) Larger than a "bit", but smaller than a "word". Although
+      "byte" almost always means "octet" today, bytes had other sizes
+      (e.g., six bits, nine bits) in earlier computer architectures.
+
+   $ CA
+      See: certification authority.
+
+
+
+
+
+
+Shirey                       Informational                     [Page 23]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ CA certificate
+      (I) "A [digital] certificate for one CA issued by another CA."
+      [X509]
+
+      (C) That is, a digital certificate whose holder is able to issue
+      digital certificates. 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."
+
+   $ call back
+      (I) An authentication technique for terminals that remotely access
+      a computer via telephone lines. The host system disconnects the
+      caller and then calls back on a telephone number that was
+      previously authorized for that terminal.
+
+   $ capability
+      (I) A token, usually an unforgeable data value (sometimes called a
+      "ticket") 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 named or indicated by the token. (See: access control
+      list, credential, digital certificate.)
+
+      (C) This concept can be implemented as a digital certificate.
+      (See: attribute certificate.)
+
+   $ CAPI
+      See: cryptographic application programming interface.
+
+   $ CAPSTONE chip
+      (N) An integrated circuit (the Mykotronx, Inc. MYK-82) with a Type
+      II cryptographic processor that implements SKIPJACK, KEA, DSA,
+      SHA, and basic mathematical functions to support asymmetric
+      cryptography, and includes the key escrow feature of the CLIPPER
+      chip. (See: FORTEZZA card.)
+
+   $ card
+      See: cryptographic card, FORTEZZA card, payment card, PC card,
+      smart card, token.
+
+   $ card backup
+      See: token backup.
+
+   $ card copy
+      See: token copy.
+
+
+
+
+
+Shirey                       Informational                     [Page 24]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ card restore
+      See: token restore.
+
+   $ cardholder
+      (I) An entity that has been issued a card.
+
+      (O) SET usage: "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 usage: 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 usage: 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 C.A. (Carlisle Adams)
+      and S.T. (Stafford Tavares). [R2144, R2612]
+
+   $ 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: compartment.)
+
+   $ CAW
+      See: certification authority workstation.
+
+   $ CBC
+      See: cipher block chaining.
+
+   $ CCA
+      See: cardholder certification authority.
+
+
+
+Shirey                       Informational                     [Page 25]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ CCITT
+      (N) Acronym for French translation of International Telephone and
+      Telegraph Consultative Committee. Now renamed ITU-T.
+
+   $ CERT
+      See: computer emergency response team.
+
+   $ certificate
+      (I) General English usage: A document that attests to the truth of
+      something or the ownership of something.
+
+      (C) Security usage: See: capability, digital certificate.
+
+      (C) PKI usage: See: attribute certificate, public-key certificate.
+
+   $ certificate authority
+      (D) ISDs SHOULD NOT use this term because it looks like sloppy use
+      of "certification authority", which is the term standardized by
+      X.509.
+
+   $ certificate chain
+      (D) ISDs SHOULD NOT use this term because it duplicates the
+      meaning of a standardized term. Instead, use "certification path".
+
+   $ certificate chain validation
+      (D) ISDs SHOULD NOT use this term because 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, validity period.)
+
+   $ certificate extension
+      See: extension.
+
+
+
+
+
+
+
+
+
+Shirey                       Informational                     [Page 26]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ certificate holder
+      (D) ISDs SHOULD NOT use this term as a synonym for the subject of
+      a digital certificate because the term is potentially ambiguous.
+      For example, the term could also refer to a system entity, such as
+      a repository, that simply has possession of a copy of the
+      certificate. (See: certificate owner.)
+
+   $ certificate management
+      (I) The functions that a CA may perform during the life cycle 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 owner
+      (D) ISDs SHOULD NOT use this term as a synonym for the subject of
+      a digital certificate because the term is potentially ambiguous.
+      For example, the term could also refer to a system entity, such as
+      a corporation, that has acquired a certificate to operate some
+      other entity, such as a Web server. (See: certificate holder.)
+
+   $ 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] (See: certification
+      practice statement.)
+
+      (C) A certificate policy can help a certificate user 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 goods within a given price range." [R2527]
+
+      (C) 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.
+
+
+
+
+
+
+Shirey                       Informational                     [Page 27]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (C) SET usage: Every 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 reactivation
+      (I) The act or process by which a digital certificate, which a CA
+      has designated for revocation but not yet listed on a CRL, is
+      returned to the valid state.
+
+   $ certificate rekey
+      (I) The act or process by which an existing public-key certificate
+      has its public key value changed by issuing a new certificate with
+      a different (usually new) public key. (See: certificate renewal,
+      certificate update, rekey.)
+
+      (C) 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 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".
+
+      (O) MISSI usage: To rekey a MISSI X.509 public-key certificate
+      means that the issuing authority creates a new certificate that is
+      identical to the old one, except the new one has a new, different
+      KEA key; or a new, different DSS key; or 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 data binding
+      asserted by an existing public-key certificate is extended in time
+      by issuing a new certificate. (See: certificate rekey, certificate
+      update.)
+
+      (C) 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
+
+
+
+Shirey                       Informational                     [Page 28]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      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) ISDs SHOULD NOT use this term because it looks like imprecise
+      use of a term standardized by PKCS #10 and used in PKIX. Instead,
+      use the standard term, "certification request".
+
+   $ 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 a revocation date.
+
+      (C) 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 before certificate
+      expiration.
+
+   $ certificate revocation list (CRL)
+      (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, X.509
+      certificate revocation list.)
+
+      (O) "A signed list indicating a set of certificates that are no
+      longer considered valid by the certificate issuer. After a
+      certificate appears on a CRL, it is deleted from a subsequent CRL
+      after the certificate's expiry. CRLs may be used to identify
+      revoked public-key certificates or attribute certificates and may
+      represent revocation of certificates issued to authorities or to
+      users. The term CRL is also commonly used as a generic term
+      applying to all the different types of revocation lists, including
+      CRLs, ARLs, ACRLs, etc." [FPDAM]
+
+   $ certificate revocation tree
+      (I) A mechanism for distributing notice 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
+      (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.
+
+
+
+
+Shirey                       Informational                     [Page 29]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (O) "An integer value, unique within the issuing CA, which is
+      unambiguously associated with a certificate issued by that CA."
+      [X509]
+
+   $ certificate status responder
+      (N) FPKI usage: A trusted on-line server that acts for a CA to
+      provide authenticated certificate status information to
+      certificate users. [FPKI] Offers an alternative to issuing a CRL,
+      but is not supported in X.509. (See: certificate revocation tree.)
+
+   $ certificate update
+      (I) The act or process by which non-key data items bound in an
+      existing public-key certificate, especially authorizations granted
+      to the subject, are changed by issuing a new certificate. (See:
+      certificate rekey, certificate renewal.)
+
+      (C) 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
+      (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.)
+
+      (O) "An entity that needs to know, with certainty, the public key
+      of another entity." [X509]
+
+      (C) The system entity may be a human being or an organization, or
+      a device or process under the control of a human or an
+      organization.
+
+      (D) ISDs SHOULD NOT use this term as a synonym for the "subject"
+      of a certificate.
+
+   $ certificate validation
+      (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.)
+
+      (O) "The process of ensuring that a certificate is valid including
+      possibly the construction and processing of a certification path,
+      and ensuring that all certificates in that path have not expired
+      or been revoked." [FPDAM]
+
+
+
+
+
+Shirey                       Informational                     [Page 30]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (C) To validate a certificate, a certificate user checks that the
+      certificate is properly formed and signed and currently in force:
+
+       - Checks the signature: Employs 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 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.
+
+       - 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. (CRLs themselves require
+         a similar validation process.)
+
+   $ certification
+      (I) Information system usage: Technical evaluation (usually made
+      in support of an accreditation action) of an information system's
+      security features and other safeguards to establish the extent to
+      which the system's design and implementation meet specified
+      security requirements. [FP102] (See: accreditation.)
+
+      (I) Digital certificate usage: The act or process of vouching for
+      the truth and accuracy of the binding between data items in a
+      certificate. (See: certify.)
+
+      (I) Public key usage: 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. In addition to binding a key to a name, a
+      public-key certificate may bind those items to other restrictive
+      or explanatory data items. (See: X.509 public-key certificate.)
+
+      (O) SET usage: "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]
+
+
+
+Shirey                       Informational                     [Page 31]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ certification authority (CA)
+      (I) An entity that issues digital certificates (especially X.509
+      certificates) and vouches for the binding between the data items
+      in a certificate.
+
+      (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]
+
+      (C) Certificate users depend on the validity of information
+      provided by a certificate. Thus, a CA should be someone that
+      certificate users trust, and 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 life cycle of key pairs associated with the
+      certificates (see: key management).
+
+   $ certification authority workstation (CAW)
+      (I) A computer system that enables a CA to issue digital
+      certificates and supports other certificate management functions
+      as required.
+
+   $ certification hierarchy
+      (I) A tree-structured (loop-free) topology of relationships among
+      CAs and the entities to whom the CAs issue public-key
+      certificates. (See: hierarchical PKI.)
+
+      (C) 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 of the hierarchy issue certificates only to non-CA
+      entities, called "end 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.
+
+      (O) MISSI usage: A MISSI certification hierarchy has three or four
+      levels of CAs:
+
+       - A CA at the highest level, the top CA, is a "policy approving
+         authority".
+       - A CA at the second-highest level is a "policy creation
+         authority".
+
+
+
+
+Shirey                       Informational                     [Page 32]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+       - 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".
+
+      (O) PEM usage: A PEM certification hierarchy 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".
+
+      (O) SET usage: A SET certification hierarchy 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
+      (I) An ordered sequence of public-key certificates (or a sequence
+      of public-key certificates followed by 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
+      a certified public key (or certified attributes) of the entity
+      that is the subject of that last certificate. (See: certificate
+      validation, valid certificate.)
+
+      (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." [X509, R2527]
+
+      (C) The path is the "list of certificates needed to allow a
+      particular user to obtain the public key of another." [X509] The
+      list is "linked" in the sense that the digital signature of each
+      certificate (except 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 owned by the entity that
+      signed.
+
+
+
+
+Shirey                       Informational                     [Page 33]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (C) In the X.509 quotation in the previous "C" paragraph, 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
+      should be a trusted certificate (it might be a root certificate)
+      or the signature on the first certificate should be verified by a
+      trusted key (it might be a root key), but such trust is defined
+      relative to each user, not absolutely for all users.
+
+   $ certification policy
+      (D) ISDs SHOULD NOT use this term. 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." [ABA96, R2527] (See: certificate
+      policy.)
+
+      (C) 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 employs 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. [ABA]
+
+      (C) 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 a single CPS may support multiple
+      certificate policies, which may be used for different application
+      purposes or by different user communities. Multiple CAs, each with
+      a different CPS, may support the same certificate policy. [R2527]
+
+   $ certification request
+      (I) A algorithm-independent transaction format, defined by PCKS
+      #10 and used in PKIX, that contains a DN, a public key, and
+      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.
+
+
+
+
+
+
+
+Shirey                       Informational                     [Page 34]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ certify
+      1. (I) Issue a digital certificate and thus vouch for the truth,
+      accuracy, and binding between data items in the certificate (e.g.,
+      see: X.509 public key certificate), such as the identity of the
+      certificate's subject and the ownership of a public key. (See:
+      certification.)
+
+      (C) 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 employs measures to verify the truth,
+      accuracy, and binding between data items in a digital certificate.
+
+      (C) A description of the measures used for verification should be
+      included in the CA's CPS.
+
+   $ CFB
+      See: cipher feedback.
+
+   $ Challenge Handshake Authentication Protocol (CHAP)
+      (I) A peer entity authentication method for PPP, using a randomly-
+      generated challenge and requiring a matching response that depends
+      on a cryptographic hash 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.
+
+   $ Challenge-Response Authentication Mechanism (CRAM)
+      (I) IMAP4 usage: 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.)
+
+      (C) The server includes a unique timestamp 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 timestamp with a shared secret that is known only to the
+      client and the server.
+
+   $ channel
+      (I) An information transfer path within a system. (See: covert
+      channel.)
+
+
+
+
+Shirey                       Informational                     [Page 35]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ CHAP
+      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 the purpose of detecting changes in
+      the data. (See: cyclic redundancy check, data integrity service,
+      error detection code, hash, keyed hash, protected checksum.)
+
+      (C) To gain confidence that a data object has not been changed, an
+      entity that later uses the data can compute a checksum and compare
+      it with the checksum that was stored or transmitted with the
+      object.
+
+      (C) Computer systems and networks employ 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).
+
+   $ chosen-ciphertext attack
+      (I) A cryptanalysis technique in which the analyst tries to
+      determine the key from knowledge of plaintext that corresponds to
+      ciphertext 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 ciphertext that corresponds to
+      plaintext selected (i.e., dictated) by the analyst.
+
+   $ CIAC
+      See: Computer Incident Advisory Capability.
+
+   $ CIK
+      See: cryptographic ignition key.
+
+   $ cipher
+      (I) A cryptographic algorithm for encryption and decryption.
+
+   $ cipher block chaining (CBC)
+      (I) An block cipher mode that enhances electronic codebook mode by
+      chaining together blocks of ciphertext it produces. [FP081] (See:
+      [R1829], [R2451].)
+
+
+
+Shirey                       Informational                     [Page 36]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (C) 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)
+      (I) An block cipher mode that enhances electronic code book mode
+      by chaining together the blocks of ciphertext it produces and
+      operating on plaintext segments of variable length less than or
+      equal to the block length. [FP081]
+
+      (C) This mode operates by using the previously generated
+      ciphertext segment as the algorithm's input (i.e., by "feeding
+      back" the ciphertext) 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.
+
+   $ ciphertext
+      (I) 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: cleartext, plaintext.)
+
+      (O) "Data produced through the use of encipherment. The semantic
+      content of the resulting data is not available." [I7498 Part 2]
+
+   $ ciphertext-only attack
+      (I) A cryptanalysis technique in which the analyst tries to
+      determine the key solely from knowledge of intercepted ciphertext
+      (although the analyst may also know other clues, such as the
+      cryptographic algorithm, the language in which the plaintext was
+      written, the subject matter of the plaintext, and some probable
+      plaintext words.)
+
+   $ CIPSO
+      See: Common IP Security Option.
+
+   $ CKL
+      See: compromised key list.
+
+   $ class 2, 3, 4, or 5
+      (O) U.S. Department of Defense usage: Levels of PKI assurance
+      based on risk and value of information to be protected [DOD3]:
+
+       - Class 2: For handling low-value information (unclassified, not
+         mission-critical, or low monetary value) or protection of
+         system-high information in low- to medium-risk environment.
+
+
+
+
+
+Shirey                       Informational                     [Page 37]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+       - Class 3: For handling medium-value information in low- to
+         medium-risk environment. Typically requires identification of a
+         system entity as a legal person, rather than merely a member of
+         an organization.
+
+       - Class 4: For handling medium- to high-value information in any
+         environment. Typically requires identification of an entity as
+         a legal person, rather than merely a member of an organization,
+         and a cryptographic hardware token for protection of keying
+         material.
+
+       - Class 5: For handling high-value information in a high-risk
+         environment.
+
+   $ classification
+   $ classification level
+      (I) (1.) A grouping of classified information to which a
+      hierarchical, restrictive security label is applied to increase
+      protection of the data. (2.) The level of protection that is
+      required to be applied to that information. (See: security level.)
+
+   $ classified
+      (I) Refers to information (stored or conveyed, in any form) that
+      is formally required by a security policy to be given data
+      confidentiality service and to be marked with a security label
+      (which in some cases might be implicit) to indicate its protected
+      status. (See: unclassified.)
+
+      (C) The term is mainly used in government, especially in the
+      military, although the concept underlying the term also applies
+      outside government. In the U.S. Department of Defense, for
+      example, it means information that has been determined pursuant to
+      Executive Order 12958 ("Classified National Security Information",
+      20 April 1995) or any predecessor order to require protection
+      against unauthorized disclosure and is marked to indicate its
+      classified status when in documentary form.
+
+   $ clean system
+      (I) A computer system in which the operating system and
+      application system software and files have just been freshly
+      installed from trusted software distribution media.
+
+      (C) A clean system is not necessarily in a secure state.
+
+   $ clearance
+      See: security clearance.
+
+
+
+
+
+Shirey                       Informational                     [Page 38]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ clearance level
+      (I) The security level of information to which a security
+      clearance authorizes a person to have access.
+
+   $ cleartext
+      (I) Data in which the semantic information content (i.e., the
+      meaning) is intelligible or is directly available. (See:
+      plaintext.)
+
+      (O) "Intelligible data, the semantic content of which is
+      available." [I7498 Part 2]
+
+      (D) ISDs SHOULD NOT use this term as a synonym for "plaintext",
+      the input to an encryption operation, because the plaintext input
+      to encryption may itself be ciphertext that was output from
+      another operation. (See: superencryption.)
+
+   $ client
+      (I) A system entity that requests and uses a service provided by
+      another system entity, called a "server". (See: server.)
+
+      (C) Usually, the requesting entity is a computer process, and it
+      makes the request on behalf of a human user. In some cases, the
+      server may itself be a client of some other server.
+
+   $ CLIPPER chip
+      (N) The Mykotronx, Inc. MYK-82, an integrated microcircuit with a
+      cryptographic processor that implements the SKIPJACK encryption
+      algorithm and supports key escrow. (See: CAPSTONE, Escrowed
+      Encryption Standard.)
+
+      (C) The key escrow scheme for a chip involves a SKIPJACK key
+      common to all chips 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. Department of Defense usage: 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 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: open security environment.)
+
+
+
+Shirey                       Informational                     [Page 39]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ code
+      (I) noun: A system of symbols used to represent information, which
+      might originally have some other representation. (See: encode.)
+
+      (D) ISDs SHOULD NOT use this term as synonym for the following:
+      (a) "cipher", "hash", or other words that mean "a cryptographic
+      algorithm"; (b) "ciphertext"; or (c) "encrypt", "hash", or other
+      words that refer to applying a cryptographic algorithm.
+
+      (D) ISDs SHOULD NOT this word as an abbreviation for the following
+      terms: country code, cyclic redundancy code, Data Authentication
+      Code, error detection code, Message Authentication Code, object
+      code, or source code. To avoid misunderstanding, use the fully
+      qualified term, at least at the point of first usage.
+
+   $ color change
+      (I) In a system that is 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.
+
+   $ Common Criteria
+   $ Common Criteria for Information Technology Security
+      (N) "The Common Criteria" is a standard for evaluating information
+      technology products and systems, such as operating systems,
+      computer networks, distributed systems, and applications. It
+      states requirements for security functions and for assurance
+      measures. [CCIB]
+
+      (C) 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" (FC)
+      and its precursor, the TCSEC. Work was done in cooperation with
+      ISO/IEC Joint Technical Committee 1 (Information Technology),
+      Subcommittee 27 (Security Techniques), Working Group 3 (Security
+      Criteria). Version 2.1 of the Criteria is equivalent to ISO's
+      International Standard 15408 [I15408]. The U.S. Government intends
+      that this standard eventually will supersede both the TCSEC and
+      FIPS PUB 140-1. (See: NIAP.)
+
+      (C) 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
+
+
+
+Shirey                       Informational                     [Page 40]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      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.
+
+   $ Common IP Security Option (CIPSO)
+      See: (secondary definition under) Internet Protocol Security
+      Option.
+
+   $ common name
+      (I) 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.)
+
+      (C) For example, "Dr. E. F. Moore", "The United Nations", or
+      "12-th Floor Laser Printer".
+
+   $ 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.
+
+      (C) Usually understood to include cryptographic algorithms and key
+      management methods and processes, devices that implement them, and
+      the life cycle management of keying material and devices.
+
+   $ community string
+      (I) A community name in the form of an octet string that serves as
+      a cleartext password in SNMP version 1. [R1157]
+
+   $ compartment
+      (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: category.)
+
+      (C) The term is usually understood to include the special handling
+      procedures to be used for the information.
+
+   $ compromise
+      See: data compromise, security compromise.
+
+
+
+
+
+Shirey                       Informational                     [Page 41]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ compromised key list (CKL)
+      (O) MISSI usage: A list that identifies keys for which
+      unauthorized disclosure or alteration may have occurred. (See:
+      compromise.)
+
+      (C) A CKL is issued by an 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
+      See: computer security.
+
+   $ 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.)
+
+      (C) For example, the CERT Coordination Center at Carnegie-Mellon
+      University (sometimes called "the" CERT) and the Computer Incident
+      Advisory Capability.
+
+   $ Computer Incident Advisory Capability (CIAC)
+      (N) A computer emergency response team in the U.S. Department of
+      Energy.
+
+   $ computer network
+      (I) A collection of host computers together with the subnetwork or
+      internetwork through which they can exchange data.
+
+      (C) 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 security (COMPUSEC)
+      (I) Measures that implement and assure security services in a
+      computer system, particularly those that assure access control
+      service.
+
+      (C) Usually understood to include functions, features, and
+      technical characteristics of computer hardware and software,
+      especially operating systems.
+
+
+
+
+
+
+
+Shirey                       Informational                     [Page 42]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ 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.)
+
+      (C) To be considered a CSIRT, an organization must do as follows:
+
+       - Provide a (secure) channel for receiving reports about
+         suspected security incidents.
+       - Provide assistance to members of its constituency in handling
+         the incidents.
+       - 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 elements 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.
+
+      (C) 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) gov(101)
+      csor(3)}.
+
+   $ COMSEC
+      See: communication security.
+
+   $ confidentiality
+      See: data confidentiality.
+
+   $ 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.)
+
+
+
+Shirey                       Informational                     [Page 43]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (C) Configuration control helps protect against unauthorized or
+      malicious alteration of a system and thus provides assurance of
+      system integrity. (See: malicious logic.)
+
+   $ confinement property
+      See: (secondary definition under) Bell-LaPadula Model.
+
+   $ connectionless data integrity service
+      (I) A security service that provides data integrity service for an
+      individual IP datagram, by detecting modification of the datagram,
+      without regard to the ordering of the datagram in a stream of
+      datagrams.
+
+      (C) A connection-oriented data integrity service would be able to
+      detect lost or reordered datagrams within a stream of datagrams.
+
+   $ 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.)
+
+   $ controlled security mode
+      (D) ISDs SHOULD NOT use this term. It was defined in an earlier
+      version of the U.S. Department of Defense policy that regulates
+      system accreditation, but was subsumed by "partitioned security
+      mode" in the current version. [DOD2]
+
+      (C) The term refers to a mode of operation of an information
+      system, wherein at least some users with access to the system have
+      neither a security clearance nor a need-to-know for all classified
+      material contained in the system. However, separation and control
+      of users and classified material on the basis, respectively, of
+      clearance and classification level are not essentially under
+      operating system control like they are in "multilevel security
+      mode".
+
+      (C) Controlled mode was intended to encourage ingenuity in meeting
+      the security requirements of Defense policy 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 the true "multilevel security mode". This was 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 permitted concurrent access to the
+      system.
+
+
+
+
+Shirey                       Informational                     [Page 44]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ cookie
+      (I) access control usage: A synonym for "capability" or "ticket"
+      in an access control system.
+
+      (I) IPsec usage: Data exchanged by ISAKMP to prevent certain
+      denial-of-service attacks during the establishment of a security
+      association.
+
+      (I) HTTP usage: 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.
+
+      (C) 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.
+
+   $ 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.)
+
+   $ copy
+      See: card copy.
+
+   $ correctness integrity
+      (I) Accuracy and consistency of the information that data values
+      represent, rather than of the data itself. Closely related to
+      issues of accountability and error handling. (See: data integrity,
+      source integrity.)
+
+   $ correctness proof
+      (I) A mathematical proof of consistency between a specification
+      for system security and the implementation of that specification.
+      (See: formal specification.)
+
+   $ countermeasure
+      (I) An action, device, procedure, or technique that reduces 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.
+
+
+
+Shirey                       Informational                     [Page 45]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (C) In an Internet protocol, a countermeasure may take the form of
+      a protocol feature, an element function, or a usage constraint.
+
+   $ country code
+      (I) An identifier that is defined for a nation by ISO. [I3166]
+
+      (C) 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.
+
+   $ covert channel
+      (I) A intra-system channel that permits two cooperating entities,
+      without exceeding their access authorizations, to transfer
+      information in a way that violates the system's security policy.
+      (See: channel, out of band.)
+
+      (O) "A communications channel that allows two cooperating
+      processes to transfer information in a manner that violates the
+      system's security policy." [NCS04]
+
+      (C) 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:
+
+       - "Timing channel": A system feature that enable 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.
+
+       - "Storage channel": 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.
+
+   $ CPS
+      See: certification practice statement.
+
+   $ cracker
+      (I) Someone who tries to break the security of, and gain access
+      to, someone else's system without being invited to do so. (See:
+      hacker and intruder.)
+
+   $ CRAM
+      See: Challenge-Response Authentication Mechanism.
+
+
+
+
+Shirey                       Informational                     [Page 46]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ CRC
+      See: cyclic redundancy check.
+
+   $ credential(s)
+      (I) Data that is transferred or presented to establish either a
+      claimed identity or the authorizations of a system entity. (See:
+      authentication information, capability, ticket.)
+
+      (O) "Data that is transferred to establish the claimed identity of
+      an entity." [I7498 Part 2]
+
+   $ critical
+      1. (I) "Critical" system resource: A condition of a service or
+      other system resource such that denial of access to (i.e., 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. (See: availability, sensitive.)
+
+      2. (N) "Critical" extension: Each extension of an X.509
+      certificate (or CRL) is marked as being either critical or non-
+      critical. If an extension is critical and a certificate user (or
+      CRL user) does not recognize the extension type or does not
+      implement its semantics, then the user is required to treat the
+      certificate (or CRL) as invalid. If an extension is non-critical,
+      a user that does not recognize or implement that extension type is
+      permitted to ignore the extension and process the rest of the
+      certificate (or CRL).
+
+   $ CRL
+      See: certificate revocation list.
+
+   $ CRL distribution point
+      See: distribution point.
+
+   $ CRL extension
+      See: extension.
+
+   $ cross-certificate
+      See: cross-certification.
+
+   $ cross-certification
+      (I) The act or process by which two CAs each certify a public key
+      of the other, issuing a public-key certificate to that other CA.
+
+      (C) Cross-certification enables users to validate each other's
+      certificate when the users are certified under different
+      certification hierarchies.
+
+
+
+
+Shirey                       Informational                     [Page 47]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ cryptanalysis
+      (I) The mathematical science that deals with analysis of a
+      cryptographic system in order to gain knowledge needed to break or
+      circumvent the protection that the system is designed to provide.
+      (See: cryptology.)
+
+      (O) "The analysis of a cryptographic system and/or its inputs and
+      outputs to derive confidential variables and/or sensitive data
+      including cleartext." [I7498 Part 2]
+
+      (C) The "O" definition states the traditional goal of
+      cryptanalysis--convert the ciphertext to plaintext (which usually
+      is cleartext) 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
+      the "I" definition reflects that. In all cases, however, a
+      cryptanalyst tries to uncover or reproduce someone else's
+      sensitive data, such as cleartext, 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
+      (D) Except as part of certain long-established terms listed in
+      this Glossary, ISDs SHOULD NOT use this abbreviated term because
+      it may be misunderstood. Instead, use "cryptography" or
+      "cryptographic".
+
+   $ cryptographic algorithm
+      (I) An algorithm that employs the science of cryptography,
+      including encryption algorithms, cryptographic hash algorithms,
+      digital signature algorithms, and 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. For
+      example, see: PKCS #11, [R2628].
+
+   $ 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.)
+
+
+
+
+
+Shirey                       Informational                     [Page 48]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ cryptographic hash
+      See: (secondary definition under) hash function.
+
+   $ cryptographic ignition key (CIK)
+      (I) A physical (usually electronic) token used to store,
+      transport, and protect cryptographic keys. (Sometimes abbreviated
+      as "crypto ignition key".)
+
+      (C) A typical use is to divide a split key between a CIK and a
+      cryptographic module, so that it is necessary to combine the two
+      to regenerate a key-encrypting key and thus activate the module
+      and other keys it contains.
+
+   $ cryptographic key
+      (I) Usually shortened to just "key". An input parameter that
+      varies the transformation performed by a cryptographic algorithm.
+
+      (O) "A sequence of symbols that controls the operations of
+      encipherment and decipherment." [I7498 Part 2]
+
+      (C) If a key value needs to be kept secret, the sequence of
+      symbols (usually bits) that comprise it should be random, or at
+      least pseudo-random, because that makes the key hard for an
+      adversary to guess. (See: cryptanalysis, brute force attack.)
+
+   $ Cryptographic Message Syntax (CMS)
+      (I) A encapsulation syntax for digital signatures, hashes, and
+      encryption of arbitrary messages. [R2630]
+
+      (C) CMS was derived 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.
+
+   $ 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
+      (I) A set of cryptographic algorithms together with the key
+      management processes that support use of the algorithms in some
+      application context.
+
+
+
+
+Shirey                       Informational                     [Page 49]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (C) This "I" definition covers a wider range of algorithms than
+      the following "O" definition:
+
+      (O) "A collection of transformations from plaintext into
+      ciphertext 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
+      (I) A portable, user-controlled, physical device used to store
+      cryptographic information and possibly perform cryptographic
+      functions. (See: cryptographic card, token.)
+
+      (C) A smart token may implement some set of cryptographic
+      algorithms and may implement related algorithms and 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
+      (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.)
+
+      (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 Part 2]
+
+   $ Cryptoki
+      See: (secondary definition under) PKCS #11.
+
+   $ cryptology
+      (I) The science that includes both cryptography and cryptanalysis,
+      and sometimes is said to include steganography.
+
+   $ cryptonet
+      (I) A group of system entities that share a secret cryptographic
+      key for a symmetric algorithm.
+
+
+
+
+
+
+Shirey                       Informational                     [Page 50]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ cryptoperiod
+      (I) The time span during which a particular key is authorized to
+      be used in a cryptographic system. (See: key management.)
+
+      (C) 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 cryptanalysis.
+
+      (C) Although we deprecate its prefix, this term is long-
+      established in COMPUSEC usage. (See: crypto) In the context of
+      certificates and public keys, "key lifetime" and "validity period"
+      are often used instead.
+
+   $ cryptosystem
+      (D) ISDs SHOULD NOT use this term as an abbreviation for
+      cryptographic system. (For rationale, see: crypto.)
+
+   $ CSIRT
+      See: computer security incident response team.
+
+   $ CSOR
+      See: Computer Security Objects Register.
+
+   $ cut-and-paste attack
+      (I) An active attack on the data integrity of ciphertext, effected
+      by replacing sections of ciphertext with other ciphertext, such
+      that the result appears to decrypt correctly but actually decrypts
+      to plaintext that is forged to the satisfaction of the attacker.
+
+   $ cyclic redundancy check (CRC)
+      (I) Sometimes called "cyclic redundancy code". 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.
+
+   $ DAC
+      See: Data Authentication Code, discretionary access control.
+
+   $ DASS
+      See: Distributed Authentication Security Service.
+
+   $ data
+      (I) Information in a specific physical representation, usually a
+      sequence of symbols that have meaning; especially a representation
+      of information that can be processed or produced by a computer.
+
+
+
+
+Shirey                       Informational                     [Page 51]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ Data Authentication Algorithm
+      (N) A keyed hash function equivalent to DES cipher block chaining
+      with IV = 0. [A9009]
+
+      (D) ISDs SHOULD NOT use the uncapitalized form of this term as a
+      synonym for other kinds of checksums.
+
+   $ data authentication code vs. Data Authentication Code (DAC)
+      1. (N) Capitalized: "The Data Authentication Code" refers to a
+      U.S. Government standard [FP113] for a checksum that is computed
+      by the Data Authentication Algorithm. (Also known as the ANSI
+      standard Message Authentication Code [A9009].)
+
+      2. (D) Not capitalized: ISDs SHOULD NOT use "data authentication
+      code" as a synonym for another kind of checksum, because this term
+      mixes concepts in a potentially misleading way. (See:
+      authentication code.) Instead, use "checksum", "error detection
+      code", "hash", "keyed hash", "Message Authentication Code", or
+      "protected checksum", depending on what is meant.
+
+   $ data compromise
+      (I) A security incident in which information is exposed to
+      potential unauthorized access, such that unauthorized disclosure,
+      alteration, or use of the information may have occurred. (See:
+      compromise.)
+
+   $ data confidentiality
+      (I) "The property that information is not made available or
+      disclosed to unauthorized individuals, entities, or processes
+      [i.e., to any unauthorized system entity]." [I7498 Part 2]. (See:
+      data confidentiality service.)
+
+      (D) ISDs SHOULD NOT use this term as a synonym for "privacy",
+      which is a different concept.
+
+   $ data confidentiality service
+      (I) A security service that protects data against unauthorized
+      disclosure. (See: data confidentiality.)
+
+      (D) ISDs 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 as part of the U.S.
+      Government's Data Encryption Standard. 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: DES,
+      symmetric cryptography.)
+
+
+
+Shirey                       Informational                     [Page 52]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (C) This algorithm is usually referred to as "DES". The algorithm
+      has also been adopted in standards outside the Government (e.g.,
+      [A3092]).
+
+   $ data encryption key (DEK)
+      (I) A cryptographic key that is used to encipher application data.
+      (See: key-encrypting key.)
+
+   $ Data Encryption Standard (DES)
+      (N) A U.S. Government standard [FP046] that specifies the Data
+      Encryption Algorithm and states policy for using the algorithm to
+      protect unclassified, sensitive data. (See: AES, DEA.)
+
+   $ data integrity
+      (I) The property that data has not been changed, destroyed, or
+      lost in an unauthorized or accidental manner. (See: data integrity
+      service.)
+
+      (O) "The property that information has not been modified or
+      destroyed in an unauthorized manner." [I7498 Part 2]
+
+      (C) Deals with constancy of and confidence in data values, not
+      with the information that the values represent (see: correctness
+      integrity) or 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.)
+
+      (C) 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.
+
+      (C) 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
+      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
+
+
+
+
+Shirey                       Informational                     [Page 53]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      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 Part 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.)
+
+      (C) 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.
+
+      (C) 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.
+
+      (C) This service is usually bundled with connectionless data
+      integrity service. (See: (relationship between data integrity
+      service and authentication services under) data integrity service.
+
+   $ data privacy
+      (D) ISDs SHOULD NOT use this term because it mix concepts in a
+      potentially misleading way. Instead, use either "data
+      confidentiality" or "privacy", depending on what is meant.
+
+   $ data security
+      (I) The protection of data from disclosure, alteration,
+      destruction, or loss that either is accidental or is intentional
+      but unauthorized.
+
+      (C) Both data confidentiality service and data integrity service
+      are needed to achieve data security.
+
+   $ datagram
+      (I) "A self-contained, independent entity of data carrying
+      sufficient information to be routed from the source to the
+      destination." [R1983]
+
+   $ DEA
+      See: Data Encryption Algorithm.
+
+
+
+Shirey                       Informational                     [Page 54]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ deception
+      See: (secondary definition under) threat consequence.
+
+   $ decipher
+      (D) ISDs SHOULD NOT use this term as a synonym for "decrypt",
+      except in special circumstances. (See: (usage discussion under)
+      encryption.)
+
+   $ decipherment
+      (D) ISDs SHOULD NOT use this term as a synonym for "decryption",
+      except in special circumstances. (See: (usage discussion under)
+      encryption.)
+
+   $ decode
+      (I) Convert encoded data back to its original form of
+      representation. (See: decrypt.)
+
+      (D) ISDs SHOULD NOT use this term as a synonym for "decrypt",
+      because that would mix concepts in a potentially misleading way.
+
+   $ decrypt
+      (I) Cryptographically restore ciphertext to the plaintext form it
+      had before encryption.
+
+   $ decryption
+      See: (secondary definition under) encryption.
+
+   $ dedicated security mode
+      (I) A mode of operation of an information system, wherein all
+      users have the clearance or authorization, and the need-to-know,
+      for all data handled by the system. In this mode, the system may
+      handle either a single classification level or category of
+      information or a range of levels and categories. [DOD2]
+
+      (C) This mode is defined formally in U.S. Department of Defense
+      policy regarding system accreditation, but the term is also used
+      outside the Defense Department and outside the Government.
+
+   $ default account
+      (I) A system login account (usually accessed with a user name and
+      password) that has been predefined in a manufactured system to
+      permit initial access when the system is first put into service.
+
+      (C) Sometimes, the default user name and password are the same in
+      each copy of the system. In any case, when the system is put into
+      service, the default password should immediately be changed or the
+      default account should be disabled.
+
+
+
+
+Shirey                       Informational                     [Page 55]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ degauss
+      (N) Apply a magnetic field to permanently remove, erase, or clear
+      data from a magnetic storage medium, such as a tape or disk
+      [NCS25]. Reduce magnetic flux density to zero by applying a
+      reversing magnetic field.
+
+   $ degausser
+      (N) An electrical device that can degauss magnetic storage media.
+
+   $ DEK
+      See: data encryption key.
+
+   $ delta CRL
+      (I) A partial CRL that only contains entries for X.509
+      certificates that have been revoked since the issuance of a prior,
+      base CRL. This method can be used to partition CRLs that become
+      too large and unwieldy.
+
+   $ denial of service
+      (I) The prevention of authorized access to a system resource or
+      the delaying of system operations and functions. (See:
+      availability, critical (resource of a system), flooding.)
+
+   $ DES
+      See: Data Encryption Standard.
+
+   $ dictionary attack
+      (I) An attack that uses a brute-force technique of successively
+      trying all the words in some large, exhaustive list.
+
+      (C) For example, an attack on an authentication service by trying
+      all possible passwords; or an attack on encryption 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
+      (N) A key agreement algorithm published in 1976 by Whitfield
+      Diffie and Martin Hellman [DH76, R2631].
+
+      (C) Diffie-Hellman 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.
+
+      (C) The difficulty of breaking Diffie-Hellman is considered to be
+      equal to the difficulty of computing discrete logarithms modulo a
+      large prime. The algorithm is described in [R2631] and [Schn]. In
+      brief, Alice and Bob together pick large integers that satisfy
+
+
+
+Shirey                       Informational                     [Page 56]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      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
+      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.
+      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, capability, public-key certificate.)
+
+      (D) ISDs SHOULD NOT use this term to refer to a signed CRL or CKL.
+      Although the recommended definition can be interpreted to include
+      those items, the security community does not use the term with
+      those meanings.
+
+   $ digital certification
+      (D) ISDs SHOULD NOT use this term as a synonym for
+      "certification", 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 digital envelope for a recipient is a combination of (a)
+      encrypted content data (of any kind) and (b) the content
+      encryption key in an encrypted form that has been prepared for the
+      use of the recipient.
+
+      (C) In ISDs, this 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 yet widely established.
+
+
+
+Shirey                       Informational                     [Page 57]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (C) 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 PCKS #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
+      conveying the content encryption key.
+
+   $ Digital ID(service mark)
+      (D) ISDs SHOULD NOT use this term as a synonym for "digital
+      certificate" because (a) it is the service mark of a commercial
+      firm, (b) it unnecessarily duplicates the meaning of other, well-
+      established terms, and (c) a certificate is not always used as
+      authentication information. In some contexts, however, it may be
+      useful to explain that the key conveyed in a public-key
+      certificate can be used to verify an identity and, therefore, that
+      the certificate can be thought of as digital identification
+      information. (See: identification information.)
+
+   $ digital key
+      (C) 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) Analogous to a notary public. Provides a trusted date-and-time
+      stamp for a document, so that someone can later prove that the
+      document existed at a point in time. May also verify the
+      signature(s) on a signed document before applying the stamp. (See:
+      notarization.)
+
+   $ digital signature
+      (I) A value computed with a cryptographic algorithm and appended
+      to 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,
+      digitized signature, electronic signature, signer.)
+
+      (I) "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 Part 2]
+
+
+
+
+Shirey                       Informational                     [Page 58]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (C) Typically, 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.
+
+      (C) Some digital signature schemes use a asymmetric encryption
+      algorithm (e.g., see: 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.
+
+      (C) Other digital signature schemes (e.g., see: DSS) transform the
+      hash result with an algorithm (e.g., see: 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.
+
+   $ Digital Signature Algorithm (DSA)
+      (N) An asymmetric cryptographic algorithm that produces 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:
+      Digital Signature Standard.)
+
+   $ Digital Signature Standard (DSS)
+      (N) The U.S. Government standard [FP186] that specifies the
+      Digital Signature Algorithm (DSA), which involves asymmetric
+      cryptography.
+
+   $ 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.
+
+
+
+Shirey                       Informational                     [Page 59]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (C) The set of embedded bits (the digital watermark) 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) ISDs SHOULD NOT use this term because there is no current
+      consensus on its definition. Although it appears to be used mainly
+      to refer to various forms of digitized images of handwritten
+      signatures, the term should be avoided because it might be
+      confused with "digital signature".
+
+   $ directory
+   $ Directory
+      See: directory vs. Directory.
+
+   $ Directory Access Protocol (DAP)
+      (N) An OSI protocol [X519] for communication between a Directory
+      User Agent (a client) and a Directory System Agent (a server).
+      (See: Lightweight Directory Access Protocol.)
+
+   $ directory vs. Directory
+      1. (I) Not capitalized: The term "directory" refers generically to
+      a database server or other system that provides information--such
+      as a digital certificate or CRL--about an entity whose name is
+      known.
+
+      2. (I) Capitalized: "Directory" refers specifically to the X.500
+      Directory. (See: repository.)
+
+   $ disaster plan
+      (D) A synonym for "contingency plan". In the interest of
+      consistency, ISDs SHOULD use "contingency plan" instead of
+      "disaster plan".
+
+   $ disclosure (i.e., unauthorized disclosure)
+      See: (secondary definition under) threat consequence.
+
+   $ discretionary access control (DAC)
+      (I) An access control service that enforces a security policy
+      based on the identity of system entities and their authorizations
+      to access system resources. (See: access control list, identity-
+      based security policy, mandatory access control.)
+
+
+
+
+
+Shirey                       Informational                     [Page 60]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (C) This service is termed "discretionary" because an entity might
+      have access rights that permit the entity, by its own volition, to
+      enable another entity to access some resource.
+
+      (O) "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]
+
+   $ disruption
+      See: (secondary definition under) threat consequence.
+
+   $ Distinguished Encoding Rules (DER)
+      (N) A subset of the Basic Encoding Rules, which gives exactly one
+      way to represent any ASN.1 value as an octet string [X690].
+
+      (C) Since there is more than one way to encode ASN.1 in BER, DER
+      is used in applications in which a unique encoding is needed, such
+      as when a digital signature is computed on an ASN.1 value.
+
+   $ distinguished name (DN)
+      (I) An identifier that uniquely represents an object in the X.500
+      Directory Information Tree (DIT) [X501]. (See: domain name.)
+
+      (C) 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 Authentication Security Service (DASS)
+      (I) An experimental Internet protocol [R1507] that uses
+      cryptographic mechanisms to provide strong, mutual authentication
+      services in a distributed environment.
+
+   $ 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 might list the certificate.
+
+      (C) 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. 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
+
+
+
+
+Shirey                       Informational                     [Page 61]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      other authority, and (c) contain revocation entries for only a
+      subset of the full set of certificates issued by one CA or (c')
+      contain revocation entries for multiple CAs.
+
+   $ DN
+      See: distinguished name.
+
+   $ DNS
+      See: Domain Name System.
+
+   $ DOI
+      See: Domain of Interpretation.
+
+   $ domain
+      (I) Security usage: An environment or context that is defined by a
+      security policy, security model, or security architecture to
+      include a set of system resources and the set of system entities
+      that have the right to access the resources. (See: domain of
+      interpretation, security perimeter.)
+
+      (I) Internet usage: That part of the Internet domain name space
+      tree [R1034] that is at or below the name the 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. (See: Domain Name System.)
+
+      (O) MISSI usage: The domain of a MISSI CA is the set of MISSI
+      users whose certificates are signed by the CA.
+
+      (O) OSI usage: An administrative partition of a complex
+      distributed OSI system.
+
+   $ domain name
+      (I) The style of identifier--a sequence of case-insensitive ASCII
+      labels separated by dots ("bbn.com.")--defined for subtrees in the
+      Internet Domain Name System [R1034] and used in other 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: distinguished name,
+      domain.)
+
+      (C) The domain 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). The root's label is the null
+
+
+
+Shirey                       Informational                     [Page 62]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      string, so a complete domain name properly ends in a dot. The top-
+      level domains, those immediately below the root, include COM, EDU,
+      GOV, INT, MIL, NET, ORG, and two-letter country codes (such as US)
+      from ISO-3166. [R1591] (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 translating a domain name-style host name into an
+      IP address (e.g., "rosslyn.bbn.com" is "192.1.7.10") and locating
+      a host that accepts mail for some mailbox address. [R1034]
+
+      (C) 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.
+
+      (C) Extensions to the DNS [R2065, R2137, R2536] support (a) key
+      distribution for public keys needed for the DNS and for other
+      protocols, (b) data origin authentication service and data
+      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 usage: An ISAKMP/IKE DOI defines payload formats,
+      exchange types, and conventions for naming security-relevant
+      information such as security policies or cryptographic algorithms
+      and modes.
+
+      (C) For example, see [R2407]. 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 the nonhierarchical categories of A include
+      all of those of B.
+
+
+
+Shirey                       Informational                     [Page 63]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ dongle
+      (I) A portable, physical, electronic device that is required to be
+      attached to a computer to enable a particular software program to
+      run. (See: token.)
+
+      (C) A dongle is essentially a physical key used for copy
+      protection of software, because 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) Reduce the classification level of information in an
+      authorized manner.
+
+   $ draft RFC
+      (D) ISDs SHOULD NOT use this term, because the Request for Comment
+      series is archival in nature and does not have a "draft" category.
+      (Instead, see: Internet Draft, Draft Standard (in Internet
+      Standard).)
+
+   $ DSA
+      See: Digital Signature Algorithm.
+
+   $ DSS
+      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
+      (D) ISDs SHOULD NOT use this term except when stated as
+      "SET(trademark) dual signature" with the following meaning:
+
+      (O) SET usage: A single digital signature that protects two
+      separate messages by including the hash results for both sets in a
+      single encrypted value. [SET2]
+
+
+
+
+
+
+
+
+Shirey                       Informational                     [Page 64]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (C) 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.
+
+   $ EAP
+      See: Extensible Authentication Protocol
+
+   $ eavesdropping
+      (I) Passive wiretapping done secretly, i.e., without the knowledge
+      of the originator or the intended recipients of the communication.
+
+   $ ECB
+      See: electronic codebook.
+
+   $ ECDSA
+      See: Elliptic Curve Digital Signature Algorithm.
+
+   $ economy of mechanism
+      (I) The principle that each security mechanism should be designed
+      to be as simple as possible, so that the mechanism can be
+      correctly implemented and so that it can be verified that the
+      operation of the mechanism enforces the containing system's
+      security policy. (See: least privilege.)
+
+   $ EDI
+      See: electronic data interchange.
+
+   $ EDIFACT
+      See: (secondary definition under) electronic data interchange.
+
+   $ EE
+      (D) ISDs SHOULD NOT use this abbreviation because of possible
+      confusion among "end entity", "end-to-end encryption", "escrowed
+      encryption standard", and other terms.
+
+   $ EES
+      See: Escrowed Encryption Standard.
+
+   $ 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, Schn]
+
+
+
+
+
+
+Shirey                       Informational                     [Page 65]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ electronic codebook (ECB)
+      (I) An 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 ciphertext [FP081].
+
+   $ electronic commerce
+      (I) General usage: 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.
+
+      (O) SET usage: "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.
+
+      (C) 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 signature
+      (D) ISDs SHOULD NOT use this term because there is no current
+      consensus on its definition. (Instead, see: digital signature.)
+
+   $ elliptic curve cryptography (ECC)
+      (I) A type of asymmetric cryptography based on mathematics of
+      groups that are defined by the points on a curve.
+
+      (C) The most efficient implementation of ECC is claimed to be
+      stronger per bit of key (against cryptanalysis that uses a brute
+      force attack) than any other known form of asymmetric
+      cryptography. ECC is based on mathematics different than the kinds
+      originally used to define the Diffie-Hellman algorithm and the
+      Digital Signature Algorithm. ECC is based on the mathematics of
+      groups defined by the points on a curve, where the curve is
+      defined by a quadratic equation in a finite field. ECC can be used
+      to define both an algorithm for key agreement that is an analog of
+      Diffie-Hellman and an algorithm for digital signature that is an
+      analog of DSA. (See: ECDSA.)
+
+   $ Elliptic Curve Digital Signature Algorithm (ECDSA)
+      (N) A standard [A9062] that is the elliptic curve cryptography
+      analog of the Digital Signature Algorithm.
+
+
+
+Shirey                       Informational                     [Page 66]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ emanation
+      (I) An signal (electromagnetic, acoustic, or other medium) that is
+      emitted by a system (through radiation or conductance) as a
+      consequence (i.e., byproduct) of its operation, and that may
+      contain information. (See: TEMPEST.)
+
+   $ emanations security (EMSEC)
+      (I) Physical constraints to prevent information compromise through
+      signals emanated by a system, particular the application of
+      TEMPEST technology to block electromagnetic radiation.
+
+   $ emergency plan
+      (D) A synonym for "contingency plan". In the interest of
+      consistency, ISDs SHOULD use "contingency plan" instead of
+      "emergency plan".
+
+   $ EMSEC
+      See: emanations security.
+
+   $ EMV
+      (I) An 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 IPsec protocol [R2406] designed to provide a mix
+      of security services--especially data confidentiality service--in
+      the Internet Protocol. (See: Authentication Header.)
+
+      (C) ESP may be used alone, or in combination with the IPsec AH
+      protocol, 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) ISDs SHOULD NOT use this term as a synonym for "encrypt".
+      However, see the usage note under "encryption".
+
+
+
+
+
+
+Shirey                       Informational                     [Page 67]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ encipherment
+      (D) ISDs SHOULD NOT use this term as a synonym for "encryption",
+      except in special circumstances that are explained in the usage
+      discussion under "encryption".
+
+   $ encode
+      (I) Use a system of symbols to represent information, which might
+      originally have some other representation. (See: decode.)
+
+      (C) Examples include Morse code, ASCII, and BER.
+
+      (D) ISDs SHOULD NOT use this term as a synonym for "encrypt",
+      because encoding is not usually intended to conceal meaning.
+
+   $ encrypt
+      (I) Cryptographically transform data to produce ciphertext. (See:
+      encryption.)
+
+   $ encryption
+      (I) Cryptographic transformation of data (called "plaintext") into
+      a form (called "ciphertext") that conceals the data's original
+      meaning to prevent it from being known or used. If the
+      transformation is reversible, the corresponding reversal process
+      is called "decryption", which is a transformation that restores
+      encrypted data to its original state. (See: cryptography.)
+
+      (C) Usage note: For this concept, ISDs should use the verb "to
+      encrypt" (and related variations: encryption, decrypt, and
+      decryption). However, because of cultural biases, some
+      international usage, particularly ISO and CCITT standards, avoids
+      "to encrypt" and instead uses the verb "to encipher" (and related
+      variations: encipherment, decipher, decipherment).
+
+      (O) "The cryptographic transformation of data (see: cryptography)
+      to produce ciphertext." [I7498 Part 2]
+
+      (C) Usually, the plaintext input to an encryption operation is
+      cleartext. But in some cases, the plaintext may be ciphertext that
+      was output from another encryption operation. (See:
+      superencryption.)
+
+      (C) Encryption and decryption involve a mathematical algorithm for
+      transforming data. In addition to the data to be transformed, the
+      algorithm has one or more inputs that are control parameters: (a)
+      a key value that varies the transformation and, in some cases, (b)
+      an initialization value that establishes the starting state of the
+      algorithm.
+
+
+
+
+Shirey                       Informational                     [Page 68]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ 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.
+
+      C) A v3 X.509 public-key certificate may have a "keyUsage"
+      extension that indicates the purpose for which the certified
+      public key is intended.
+
+   $ end entity
+      (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 a purpose or purposes other than
+      signing a digital certificate; i.e., an entity that is not a CA.
+
+      (D) "A certificate subject which uses its public [sic] key for
+      purposes other than signing certificates." [X509]
+
+      (C) ISDs SHOULD NOT use the X.509 definition, because it is
+      misleading and incomplete. First, the X.509 definition should say
+      "private key" rather than "public key" because certificates are
+      not usefully signed with a public key. Second, the X.509
+      definition is weak 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
+      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".
+
+      (C) 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.
+
+      (C) Whether a subject can play both CA and non-CA roles, with
+      either the same or different certificates, is a matter of policy.
+      (See: certification practice statement.) 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".
+
+
+
+
+
+
+
+Shirey                       Informational                     [Page 69]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ end system
+      (I) An OSI term for a computer that implements all seven layers of
+      the OSIRM and may attach to a subnetwork. (In the context of the
+      Internet Protocol Suite, usually called a "host".)
+
+   $ end-to-end encryption
+      (I) Continuous protection of data that flows between two points in
+      a network, provided by encrypting data when it leaves its source,
+      leaving it encrypted while it passes through any intermediate
+      computers (such as routers), and decrypting only when the data
+      arrives at the intended destination. (See: link encryption,
+      wiretapping.)
+
+      (C) 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
+      (I) General usage: A system entity, usually a human individual,
+      that makes use of system resources, primarily for application
+      purposes as opposed to system management purposes.
+
+      (I) PKI usage: A synonym for "end entity"; but the term "end
+      entity" is preferred.
+
+   $ 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.)
+
+   $ ephemeral key
+      (I) A public key or a private key that is relatively short-lived.
+      (See: session key.)
+
+   $ error detection code
+      (I) A checksum designed to detect, but not correct, accidental
+      (i.e., unintentional) changes in data.
+
+   $ Escrowed Encryption Standard (EES)
+      (N) A U.S. Government standard [FP185] that specifies use of a
+      symmetric encryption algorithm (SKIPJACK) and a Law Enforcement
+
+
+
+
+
+Shirey                       Informational                     [Page 70]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      Access Field (LEAF) creation method to implement part of a key
+      escrow system that provides for decryption of encrypted
+      telecommunications when interception is lawfully authorized.
+
+      (C) Both SKIPJACK and the LEAF are to be implemented in equipment
+      used to encrypt and decrypt unclassified, sensitive
+      telecommunications data.
+
+   $ ESP
+      See: Encapsulating Security Payload.
+
+   $ Estelle
+      (N) A language (ISO 9074-1989) for formal specification of
+      computer network protocols.
+
+   $ evaluated products list
+      (O) General usage: A list of information system equipment items
+      that have been evaluated against, and found to be compliant with,
+      a particular set of criteria.
+
+      (O) U.S. Department of Defense usage: The Evaluated Products List
+      (http://www.radium.ncsc.mil/tpep/epl/) contains items that have
+      been evaluated against the TCSEC by the NCSC, or against the
+      Common Criteria by the NCSC or one of its partner agencies in
+      another county. The List forms Chapter 4 of NSA's "Information
+      Systems Security Products and Services Catalogue".
+
+   $ evaluated system
+      (I) Refers to a system that has been evaluated against security
+      criteria such as the TCSEC or the Common Criteria.
+
+   $ expire
+      See: certificate expiration.
+
+   $ exposure
+      See: (secondary definition under) threat consequence.
+
+   $ Extensible Authentication Protocol
+      (I) A framework that supports multiple, optional authentication
+      mechanisms for PPP, including cleartext passwords, challenge-
+      response, and arbitrary dialog sequences. [R2284]
+
+      (C) This protocol is intended for use primarily by a host or
+      router that connects to a PPP network server via switched circuits
+      or dial-up lines.
+
+
+
+
+
+
+Shirey                       Informational                     [Page 71]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ extension
+      (I) A data item defined for optional inclusion in a v3 X.509
+      public-key certificate or a v2 X.509 CRL.
+
+      (C) The formats defined in X.509 can be extended to provide
+      methods for associating additional attributes with subjects and
+      public keys and for managing a certification hierarchy:
+
+       - "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.
+
+       - "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.
+
+       - "Private extension": Additional extensions, each named by an
+         OID, can be locally defined as needed by applications or
+         communities. (See: PKIX private extension, SET private
+         extensions.)
+
+   $ extranet
+      (I) A computer network that an organization uses to carry
+      application data traffic between the organization and its business
+      partners. (See: intranet.)
+
+      (C) An extranet can be implemented securely, either on the
+      Internet or using Internet technology, by constructing the
+      extranet as a VPN.
+
+   $ fail safe
+      (I) A mode of system termination that automatically leaves system
+      processes and components in a secure state when a failure occurs
+      or is detected in the system.
+
+   $ fail soft
+      (I) Selective termination of affected non-essential system
+      functions and processes when a failure occurs or is detected in
+      the system.
+
+   $ failure control
+      (I) A methodology used to provide fail-safe or fail-soft
+      termination and recovery of functions and processes when failures
+      are detected or occur in a system. [FP039]
+
+
+
+
+
+Shirey                       Informational                     [Page 72]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ Federal Information Processing Standards (FIPS)
+      (N) The Federal Information Processing Standards Publication (FIPS
+      PUB) series issued by the U.S. National Institute of Standards and
+      Technology as technical guidelines for U.S. Government
+      procurements of information processing system equipment and
+      services. [FP031, FP039, FP046, FP081, FP102, FP113, FP140, FP151,
+      FP180, FP185, FP186, FP188]
+
+      (C) Issued 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.
+
+   $ Federal Public-key Infrastructure (FPKI)
+      (N) A PKI being planned to establish facilities, specifications,
+      and policies needed by the U.S. Federal Government to use public-
+      key certificates for INFOSEC, COMSEC, and electronic commerce
+      involving unclassified but sensitive applications and interactions
+      between Federal agencies as well as with entities of other
+      branches of the Federal Government, state, and local governments,
+      business, 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 OSI layer 2. Was renamed "FIPS
+      PUB 140" when responsibility for protecting unclassified,
+      sensitive information was transferred from NSA to NIST, and then
+      was superseded by FIPS PUB 140-1.
+
+   $ File Transfer Protocol (FTP)
+      (I) A TCP-based, application-layer, Internet Standard protocol
+      [R0959] for moving data files from one computer to another.
+
+   $ filtering router
+      (I) An internetwork router that selectively prevents the passage
+      of data packets according to a security policy.
+
+      (C) A filtering router may be used as a firewall or part of a
+      firewall. A router usually receives a packet from a network and
+      decides where to forward it on a second network. A filtering
+      router does the same, but first decides whether the packet should
+      be forwarded at all, according to some security policy. 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]
+
+
+
+
+
+Shirey                       Informational                     [Page 73]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ 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
+      (I) A pattern of curves formed by the ridges on a fingertip. (See:
+      biometric authentication, thumbprint.)
+
+      (D) ISDs SHOULD NOT use this term as a synonym for "hash result"
+      because it mixes concepts in a potentially misleading way.
+
+      (D) ISDs SHOULD NOT use this term with the following PGP
+      definition, because the term and definition mix concepts in a
+      potentially misleading way and duplicate the meaning of "hash
+      result":
+
+      (O) PGP usage: A hash result used to authenticate a public key
+      (key fingerprint) or other data. [PGP]
+
+   $ FIPS
+      See: Federal Information Processing Standards.
+
+   $ FIPS PUB 140-1
+      (N) The U.S. Government standard [FP140] for security requirements
+      to be met by a cryptographic module used to protect unclassified
+      information in computer and communication systems. (See: Common
+      Criteria, FIPS, Federal Standard 1027.)
+
+      (C) 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.
+
+   $ firewall
+      (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.)
+
+
+
+
+Shirey                       Informational                     [Page 74]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (C) 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 security
+      policy rules to control traffic that flows in and out of the
+      protected network.
+
+      (C) 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 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 intruders out, but usually also
+      needs to let authorized users in and out.
+
+   $ 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
+      See: Forum of Incident Response and Security Teams.
+
+   $ 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]
+
+   $ flooding
+      (I) An attack that attempts to cause a failure in (especially, in
+      the security of) a computer system or other data processing entity
+      by providing more input than the entity can process properly.
+      (See: denial of service.)
+
+
+
+
+
+Shirey                       Informational                     [Page 75]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ 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.
+
+   $ flow control
+      (I) 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. (See: covert channel, simple security property, confinement
+      property.)
+
+   $ formal specification
+      (I) A specification of hardware or software functionality in a
+      computer-readable language; usually a precise mathematical
+      description of the behavior of the system with the aim of
+      providing a correctness proof.
+
+   $ 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)
+      (N) 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 that
+      contains a CAPSTONE chip, serial port modems, server boards, smart
+      cards, and software implementations.
+
+   $ Forum of Incident Response and Security Teams (FIRST)
+      (N) An international consortium of CSIRTs that work together to
+      handle computer security incidents and promote preventive
+      activities. (See: CSIRT, security incident.)
+
+      (C) FIRST was founded in 1990 and, as of September 1999, had
+      nearly 70 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
+         government, private industry, academia, and the individual.
+       - Enhance the image and status of the CSIRT community.
+
+
+
+
+Shirey                       Informational                     [Page 76]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ forward secrecy
+      See: public-key forward secrecy.
+
+   $ FPKI
+      See: Federal Public-Key Infrastructure.
+
+   $ FTP
+      See: File Transfer Protocol.
+
+   $ gateway
+      (I) A relay mechanism that attaches to two (or more) computer
+      networks that have similar functions but dissimilar
+      implementations and that enables host computers on one network to
+      communicate with hosts on the other; an intermediate system that
+      is the interface between two computer networks. (See: bridge,
+      firewall, guard, internetwork, proxy server, router, and
+      subnetwork.)
+
+      (C) In theory, gateways are conceivable at any OSI layer. In
+      practice, they operate at OSI layer 3 (see: bridge, router) or
+      layer 7 (see: proxy server). When the two networks differ in the
+      protocol by which they offer service to hosts, the gateway may
+      translate one protocol into another or otherwise facilitate
+      interoperation of hosts (see: Internet Protocol).
+
+   $ GCA
+      See: geopolitical certificate authority.
+
+   $ GeneralizedTime
+      (N) The ASN.1 data type "GeneralizedTime" (specified in 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 allowing Coordinated
+      Universal Time to be calculated. (See: Coordinated Universal Time,
+      UTCTime.)
+
+   $ Generic Security Service Application Program Interface (GSS-API)
+      (I) An Internet Standard protocol [R2078] 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 allowing the
+      application source code to be ported to different environments.
+
+      (C) "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
+
+
+
+
+Shirey                       Informational                     [Page 77]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      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]." [R2078]
+
+   $ geopolitical certificate authority (GCA)
+      (O) SET usage: 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.
+
+   $ Green Book
+      (D) Except as an explanatory appositive, ISDs SHOULD NOT use this
+      term as a synonym for "Defense Password Management Guideline"
+      [CSC2]. Instead, use the full proper name of the document or, in
+      subsequent references, a conventional abbreviation. (See: Rainbow
+      Series.)
+
+      (D) Usage note: To improve international comprehensibility of
+      Internet Standards and the Internet Standards Process, ISDs SHOULD
+      NOT use "cute" synonyms for document titles. No matter how popular
+      and clearly understood a nickname may be in one community, it is
+      likely to cause confusion 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 (at that time, CCITT) standards.
+       - "PostScript Language Program Design", Adobe Systems, Addison-
+         Wesley, 1988.
+       - IEEE 1003.1 POSIX Operating Systems Interface.
+       - "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.
+
+   $ GRIP
+      (I) A contraction of "Guidelines and Recommendations for Security
+      Incident Processing", the name of the IETF working group that
+      seeks to facilitate consistent handling of security incidents in
+      the Internet community. (See: security incident.)
+
+      (C) Guidelines to be produced by the WG will address technology
+      vendors, network service providers, and response teams in their
+      roles assisting organizations in resolving security incidents.
+      These relationships are functional and can exist within and across
+      organizational boundaries.
+
+
+
+Shirey                       Informational                     [Page 78]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ GSS-API
+      See: Generic Security Service Application Program Interface.
+
+   $ guard
+      (I) A gateway that is interposed between two networks (or
+      computers, or other information systems) operating at different
+      security levels (one level is usually higher than the other) and
+      is trusted to mediate all information transfers between the two
+      levels, either to ensure that no sensitive information from the
+      first (higher) level is disclosed to the second (lower) level, or
+      to protect the integrity of data on the first (higher) level.
+      (See: firewall.)
+
+   $ guest login
+      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.
+
+   $ hacker
+      (I) Someone with a strong interest in computers, who enjoys
+      learning about them and experimenting with them. (See: cracker.)
+
+      (C) The recommended definition is the original meaning of the term
+      (circa 1960), which then had a neutral or positive connotation of
+      "someone who figures things out and makes something cool
+      happen". Today, the term is frequently misused, especially by
+      journalists, to have the pejorative meaning of cracker.
+
+   $ handle
+      (I) (1.) 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. (2.) Noun: An on-
+      line pseudonym, particularly one used by a cracker; derived from
+      citizens band radio culture.
+
+   $ hardware
+      (I) The material physical components of a computer system. (See:
+      firmware, software.)
+
+   $ hardware token
+      See: token.
+
+
+
+
+
+
+Shirey                       Informational                     [Page 79]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ hash code
+      (D) ISDs SHOULD NOT use this term (especially not as a synonym for
+      "hash result") because it mixes concepts in a potentially
+      misleading way. A hash result is not a "code" in any sense defined
+      by this glossary. (See: code, hash result, hash value, message
+      digest.)
+
+   $ hash function
+      (I) An algorithm that computes a value based on a data object
+      (such as a message or file; usually variable-length; possibly very
+      large), thereby mapping the data object to a smaller data object
+      (the "hash result") which is usually a fixed-size value. (See:
+      checksum, keyed hash.)
+
+      (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]
+
+      (C) The kind of hash function needed for security applications is
+      called a "cryptographic hash function", an algorithm for which it
+      is computationally infeasible (because no attack is significantly
+      more efficient than brute force) to find either (a) a data object
+      that maps to a pre-specified hash result (the "one-way" property)
+      or (b) two data objects that map to the same hash result (the
+      "collision-free" property). (See: MD2, MD4, MD5, SHA-1.)
+
+      (C) A cryptographic hash is "good" in the sense stated in the "O"
+      definition for hash function. Any change to an input data object
+      will, with high probability, result in a different hash result, so
+      that the result of a cryptographic hash makes a good checksum for
+      a data object.
+
+   $ hash result
+      (I) The output of a hash function. (See: hash code, hash value.)
+
+      (O) "The output produced by a hash function upon processing a
+      message" (where "message" is broadly defined as "a digital
+      representation of data"). [ABA] (The recommended definition is
+      compatible with this ABA definition, but we avoid the unusual
+      definition of "message".)
+
+   $ hash value
+      (D) ISDs SHOULD NOT use this term (especially not as a synonym for
+      "hash result", the output of a hash function) because it might be
+      confused with "hashed value" (the input to a hash function). (See:
+      hash code, hash result, message digest.)
+
+
+
+Shirey                       Informational                     [Page 80]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ hierarchical PKI
+      (I) A PKI architecture based on a certification hierarchy. (See:
+      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.
+
+   $ hierarchy of trust
+      (D) ISDs SHOULD NOT use this term with regard to PKI, especially
+      not as a synonym for "certification hierarchy", because this term
+      mixes concepts in a potentially misleading way. (See:
+      certification hierarchy, trust, web of trust.)
+
+   $ 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.)
+
+   $ 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].)
+
+      (C) 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, OPAD = the byte 0x5C repeated B times. HMAC
+      is computed by H(K XOR OPAD, H(K XOR IPAD, inputdata)).
+
+      (C) The goals of HMAC are as follows:
+
+       - 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.
+
+
+
+
+Shirey                       Informational                     [Page 81]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ honey pot
+      (I) A system (e.g., a web server) or a 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.)
+
+      (D) It is likely that other cultures have different metaphors for
+      this concept. To ensure international understanding, ISDs should
+      not use this term unless they also provide an explanation like
+      this one. (See: (usage note under) Green Book.)
+
+   $ host
+      (I) General computer network usage: 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.)
+
+      (I) Specific Internet Protocol Suite usage: A networked computer
+      that does not forward Internet Protocol packets that are not
+      addressed to the computer itself. (See: router.)
+
+      (C) Derivation: As viewed by its users, a host "entertains"
+      guests, 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 independently connected to networks, they are not usually
+      called hosts.
+
+   $ HTML
+      See: Hypertext Markup Language.
+
+   $ HTTP
+      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. (See: S-HTTP.)
+
+   $ hybrid encryption
+      (I) An application of cryptography that combines two or more
+      encryption algorithms, particularly a combination of symmetric and
+      asymmetric encryption. (E.g., see: digital envelope.)
+
+      (C) Asymmetric algorithms require more computation than
+      equivalently strong symmetric ones. Thus, asymmetric encryption is
+      not normally used for data confidentiality except in distributing
+
+
+
+Shirey                       Informational                     [Page 82]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      symmetric keys in applications where the key data is usually short
+      (in terms of bits) compared to the data it protects. (E.g., see:
+      MSP, PEM, PGP.)
+
+   $ hyperlink
+      (I) In hypertext or hypermedia, an information object (such as a
+      word, a phrase, or an image; usually highlighted by color or
+      underscoring) that points (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.
+
+   $ 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 Hypertext Markup
+      Language and accessed using a web browser. (See: hypermedia.)
+
+   $ Hypertext Markup Language (HTML)
+      (I) A platform-independent system of syntax and semantics 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. [R1866]
+
+   $ Hypertext Transfer Protocol (HTTP)
+      (I) A TCP-based, application-layer, client-server, Internet
+      protocol [R2616] used to carry data requests and responses in the
+      World Wide Web. (See: hypertext.)
+
+   $ IAB
+      See: Internet Architecture Board.
+
+   $ IANA
+      See: Internet Assigned Numbers Authority.
+
+   $ ICANN
+      See: Internet Corporation for Assigned Names and Numbers.
+
+   $ ICMP
+      See: Internet Control Message Protocol.
+
+
+
+
+
+Shirey                       Informational                     [Page 83]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ 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
+      See: indirect certificate revocation list.
+
+   $ IDEA
+      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.)
+
+   $ Identification Protocol
+      (I) An client-server Internet protocol [R1413] for learning the
+      identity of a user of a particular TCP connection.
+
+      (C) 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 is not intended for authorization or
+      access control. At best, it provides additional auditing
+      information with respect to TCP.
+
+   $ 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 Part 2]
+      (See: rule-based security policy.)
+
+   $ IEEE
+      See: Institute of Electrical and Electronics Engineers, Inc.
+
+   $ IEEE 802.10
+      (N) An IEEE committee developing security standards for local area
+      networks. (See: SILS.)
+
+   $ IEEE P1363
+      (N) An IEEE working group, Standard for Public-Key Cryptography,
+      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
+      See: Internet Engineering Steering Group.
+
+
+
+Shirey                       Informational                     [Page 84]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ IETF
+      See: Internet Engineering Task Force.
+
+   $ IKE
+      See: IPsec Key Exchange.
+
+   $ IMAP4
+      See: Internet Message Access Protocol, version 4.
+
+   $ IMAP4 AUTHENTICATE
+      (I) A IMAP4 "command" (better described as a transaction type, or
+      a protocol-within-a-protocol) 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.)
+
+      (C) 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, GSSAPI, and S/Key--are described
+      in [R1731].
+
+   $ in the clear
+      (I) Not encrypted. (See: cleartext.)
+
+   $ indirect certificate revocation list (ICRL)
+      (I) In X.509, a CRL that may contain certificate revocation
+      notifications for certificates issued by CAs other than the issuer
+      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.
+
+      (C) Under certain conditions, this notion is equivalent to
+      "semantic security".
+
+   $ information
+      (I) Facts and ideas, which can be represented (encoded) as various
+      forms of data.
+
+   $ Information Technology Security Evaluation Criteria (ITSEC)
+      (N) Standard developed for use in the European Union; accommodates
+      a wider range of security assurance and functionality combinations
+      than the TCSEC. Superseded by the Common Criteria. [ITSEC]
+
+
+
+
+Shirey                       Informational                     [Page 85]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ INFOSEC
+      (I) Abbreviation for "information security", referring to security
+      measures that implement and assure security services in computer
+      systems (i.e., COMPUSEC) and communication systems (i.e., COMSEC).
+
+   $ initialization value (IV)
+      (I) An input parameter that sets the starting state of a
+      cryptographic algorithm or mode. (Sometimes called "initialization
+      vector" or "message indicator".)
+
+      (C) An IV can be used to introduce cryptographic variance in
+      addition to that provided by a key (see: salt), and to synchronize
+      one cryptographic process with another. For an example of the
+      latter, cipher block chaining mode requires an IV. [R2405]
+
+   $ initialization vector
+      (D) For consistency, ISDs SHOULD NOT use this term as a synonym
+      for "initialization value".
+
+   $ insider attack
+      See: (secondary definition under) attack.
+
+   $ Institute of Electrical and Electronics Engineers, Inc. (IEEE)
+      (N) The IEEE is a not-for-profit association of more than 330,000
+      individual members in 150 countries. The IEEE produces 30 percent
+      of the world's published literature in electrical engineering,
+      computers, and control technology; holds annually more than 300
+      major conferences; and has more than 800 active standards with 700
+      under development. (See: Standards for Interoperable LAN/MAN
+      Security.)
+
+   $ integrity
+      See: data integrity, correctness integrity, source integrity,
+      system integrity.
+
+   $ integrity check
+      (D) ISDs SHOULD NOT use this term as a synonym for "cryptographic
+      hash" or "protected checksum", because this term unnecessarily
+      duplicates the meaning of other, well-established terms.
+
+   $ intelligent threat
+      (I) A circumstance in which an adversary has the technical and
+      operational capability to detect and exploit a vulnerability and
+      also has the demonstrated, presumed, or inferred intent to do so.
+      (See: threat.)
+
+
+
+
+
+
+Shirey                       Informational                     [Page 86]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ 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
+      See: (secondary definition under) ISO.
+
+   $ International Traffic in Arms Regulations (ITAR)
+      (N) 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: Wassenaar Arrangement.)
+
+   $ internet
+   $ Internet
+      See: internet vs. Internet.
+
+   $ 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. [R2026]
+
+   $ 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 [R0792] 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, domain name system management, and root
+      server system management functions formerly performed under U.S.
+      Government contract by IANA and other entities.
+
+      (C) The Internet Protocol Suite, 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 object identifiers, including
+
+
+
+Shirey                       Informational                     [Page 87]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      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.
+
+      (C) 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: the allocation of IP address space, the assignment
+      of protocol parameters, the management of the DNS, and the
+      management of the DNS root server system.
+
+   $ Internet Draft
+      (I) A working document of the IETF, its areas, and its working
+      groups. (Other groups may also distribute working documents as
+      Internet Drafts.) 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 "work in progress."
+
+   $ 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. [R2026]
+
+   $ 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. [R2026, R2323]
+
+   $ Internet Message Access Protocol, version 4 (IMAP4)
+      (I) An Internet protocol [R2060] by which a client workstation can
+      dynamically access a mailbox on a server host to manipulate and
+      retrieve mail messages that the server has received and is holding
+      for the client. (See: POP3.)
+
+
+
+
+Shirey                       Informational                     [Page 88]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (C) IMAP4 has mechanisms for optionally authenticating a client to
+      a server and providing other security services. (See: IMAP4
+      AUTHENTICATE.)
+
+   $ 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 usage under) certification hierarchy.)
+
+   $ Internet Protocol (IP)
+      (I) A Internet Standard protocol (version 4 [R0791] and version 6
+      [R2460]) 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. (See: IP address, TCP/IP.)
+
+      (C) In the OSIRM, IP would be located at the top of layer 3.
+
+   $ Internet Protocol security (IPsec)
+      (I) (1.) The name of the IETF working group that is specifying a
+      security architecture [R2401] and protocols to provide security
+      services for Internet Protocol traffic. (2.) A collective name for
+      that architecture and set of protocols. (Implementation of IPsec
+      protocols is optional for IP version 4, but mandatory for IP
+      version 6.) (See: Internet Protocol Security Option.)
+
+      (C) Note that the letters "sec" are lower-case.
+
+      (C) The IPsec architecture specifies (a) security protocols (AH
+      and ESP), (b) security associations (what they are, how they work,
+      how they are managed, and associated processing), (c) key
+      management (IKE), and (d) algorithms for authentication and
+      encryption. The set of security services 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.
+
+   $ 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 the purpose of
+      carrying security information about the datagram. (See: IPsec.)
+
+      (D) ISDs SHOULD NOT use this term without a modifier to indicate
+      which of the three types is meant.
+
+
+
+
+
+Shirey                       Informational                     [Page 89]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      1. "DoD Basic Security Option" (IP option type 130): Defined for
+      use on U.S. Department of Defense common user data networks.
+      Identifies the Defense classification level at which the
+      datagram is to be protected and the protection authorities
+      whose rules apply to the datagram. [R1108]
+
+      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]
+
+      2. "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]
+
+      3. "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".) Was published as Internet-Draft [CIPSO]; not advanced
+      to RFC.
+
+   $ Internet Protocol Suite
+      See: (secondary definition under) Internet.
+
+   $ 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.
+
+      (C) ISAKMP supports negotiation of security associations for
+      protocols at all TCP/IP 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.
+
+   $ 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
+
+
+
+
+
+Shirey                       Informational                     [Page 90]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      that result. The ISOC Board of Trustees approves appointments to
+      the IAB from among nominees submitted by the IETF nominating
+      committee. [R2026]
+
+   $ 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. [R2026] (See: RFC.)
+
+      (C) 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 Internet
+      Protocol Suite. The "Internet Standards Track" has three levels of
+      increasing maturity: Proposed Standard, Draft Standard, and
+      Standard. (See: (standards levels under) ISO.)
+
+   $ Internet Standards document (ISD)
+      (C) In this Glossary, this term refers to an RFC, Internet-Draft,
+      or other item that is produced as part of the Internet Standards
+      Process [R2026]. However, neither the term nor the abbreviation is
+      widely accepted and, therefore, SHOULD NOT be used in an ISD
+      unless it is accompanied by an explanation like this. (See:
+      Internet Standard.)
+
+   $ internet vs. Internet
+      1. (I) Not capitalized: A popular abbreviation for "internetwork".
+
+      2. (I) Capitalized: "The Internet" is the single, interconnected,
+      worldwide system of commercial, government, educational, and other
+      computer networks that share the set of protocols specified by the
+      IAB [R2026] and the name and address spaces managed by the ICANN.
+
+      (C) The protocol set is named the "Internet Protocol Suite". It
+      also is popularly known as "TCP/IP", because TCP and IP are two of
+      its fundamental components. These protocols enable a user of any
+      one of the networks in the Internet to communicate with, or use
+      services located on, any of the other networks.
+
+      (C) Although the Internet does have architectural principles
+      [R1958], no Internet Standard formally defines a layered reference
+      model for the IPS that is similar to the OSIRM. However, Internet
+      community documents do refer (inconsistently) to layers:
+      application, socket, transport, internetwork, network, data link,
+
+
+
+
+Shirey                       Informational                     [Page 91]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      and physical. In this Glossary, Internet layers are referred to by
+      name to avoid confusing them with OSIRM layers, which are referred
+      to by number.
+
+   $ internetwork
+      (I) A system of interconnected networks; a network of networks.
+      Usually shortened to "internet". (See: internet vs. Internet.)
+
+      (C) An internet is usually built using OSI layer 3 gateways to
+      connect a set of subnetworks. When the subnetworks differ in the
+      OSI layer 3 protocol service they provide, the gateways sometimes
+      implement a uniform internetwork protocol (e.g., IP) that operates
+      at the top of layer 3 and hides the underlying 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, virtual private network.)
+
+   $ intruder
+      (I) An entity that gains or attempts to gain access to a system or
+      system resource without having authorization to do so. (See:
+      cracker.)
+
+   $ intrusion
+      See: security intrusion.
+
+   $ intrusion detection
+      (I) A security service that monitors and analyzes system events
+      for the purpose of finding, and providing real-time or near real-
+      time warning of, attempts to access system resources in an
+      unauthorized manner.
+
+   $ 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].
+
+      (C) 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, sufficient
+      for purposes of non-repudiation service. For example, to
+
+
+
+
+
+Shirey                       Informational                     [Page 92]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      fraudulently repudiate a validly-generated signature, a private
+      key holder may falsely claim that the key was compromised at some
+      time in the past.
+
+   $ IP
+      See: Internet Protocol.
+
+   $ IP address
+      (I) A computer's internetwork address that is assigned for use by
+      the Internet Protocol and other protocols.
+
+      (C) An IP version 4 [R0791] address is written as a series of four
+      8-bit numbers separated by periods. For example, the address of
+      the host named "rosslyn.bbn.com" is 192.1.7.10.
+
+      (C) An IP version 6 [R2373] address is written as x:x:x:x:x:x:x:x,
+      where each "x" is the hexadecimal value of one of the eight 16-bit
+      parts of the address. For example, 1080:0:0:0:8:800:200C:417A and
+      FEDC:BA98:7654:3210:FEDC:BA98:7654:3210.
+
+   $ IP Security Option
+      See: Internet Protocol Security Option.
+
+   $ IPRA
+      See: Internet Policy Registration Authority.
+
+   $ IPsec
+      See: Internet Protocol security.
+
+   $ IPsec Key Exchange (IKE)
+      (I) An Internet, IPsec, key-establishment protocol [R2409] (partly
+      based on OAKLEY) that is intended for putting in place
+      authenticated keying material for use with ISAKMP and for other
+      security associations, such as in AH and ESP.
+
+   $ IPSO
+      See: Internet Protocol Security Option.
+
+   $ ISAKMP
+      See: Internet Security Association and Key Management Protocol.
+
+   $ ISD
+      See: Internet Standards document.
+
+   $ ISO
+      (I) International Organization for Standardization, a voluntary,
+      non-treaty, non-government organization, established in 1947, with
+      voting members that are designated standards bodies of
+
+
+
+Shirey                       Informational                     [Page 93]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      participating nations and non-voting observer organizations. (See:
+      ANSI, ITU-T.)
+
+      (C) 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.)
+
+      (C) 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). (See: (standards track levels under) Internet Standard.) In
+      information technology, ISO and IEC have a joint technical
+      committee, ISO/IEC JTC 1. DISs adopted by JTC 1 are circulated to
+      national bodies for voting, and publication as an IS requires
+      approval by at least 75% of the national bodies casting a vote.
+
+   $ ISOC
+      See: Internet Society.
+
+   $ issue (a digital certificate or CRL)
+      (I) Generate and sign a digital certificate (or CRL) and, usually,
+      distribute it and make it available to potential certificate users
+      (or CRL users). (See: certificate creation.)
+
+      (C) The ABA Guidelines [ABA] explicitly limit this term to
+      certificate creation, and exclude the act of publishing. In
+      general usage, however, "issuing" a digital certificate (or CRL)
+      includes not only certificate creation but also making it
+      available to potential users, such as by storing it in a
+      repository or other directory or otherwise publishing it.
+
+   $ issuer
+      1. (I) "Issuer" of a certificate or CRL: The CA that signs the
+      digital certificate or CRL.
+
+      (C) An X.509 certificate always includes the issuer's name. The
+      name may include a common name value.
+
+      2. (N) "Issuer" of a payment card: SET usage: "The financial
+      institution or its agent that issues the unique primary account
+      number to the cardholder for the payment card brand." [SET2]
+
+
+
+
+Shirey                       Informational                     [Page 94]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (C) 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
+      See: International Traffic in Arms Regulations.
+
+   $ ITSEC
+      See: Information Technology System Evaluation Criteria.
+
+   $ 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.)
+
+      (C) 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
+      See: initialization value.
+
+   $ KDC
+      See: Key Distribution Center.
+
+   $ KEA
+      See: Key Exchange Algorithm.
+
+   $ KEK
+      See: key-encrypting key.
+
+   $ Kerberos
+      (N) 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. [R1510, Stei]
+
+      (C) Kerberos was developed by Project Athena and is named for the
+      three-headed dog guarding Hades.
+
+   $ key
+      See: cryptographic key.
+
+
+
+Shirey                       Informational                     [Page 95]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ key agreement (algorithm or protocol)
+      (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 computes the same key value. I.e., each can
+      independently generate the same key value, but that key cannot be
+      computed by other entities. (See: Diffie-Hellman, key
+      establishment, Key Exchange Algorithm, key transport.)
+
+      (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]
+
+      (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]
+
+      (C) For 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 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 that no non-legitimate party possesses the shared
+      symmetric key." [A9042]
+
+   $ key center
+      (I) A centralized key distribution process (used in symmetric
+      cryptography), usually a separate computer system, that uses key-
+      encrypting keys (master keys) to encrypt and distribute session
+      keys needed in a community of users.
+
+      (C) An ANSI standard [A9017] defines two types of key center: key
+      distribution center and key translation center.
+
+   $ key confirmation
+      (N) "The assurance of the legitimate participants in a key
+      establishment protocol that the intended parties sharing 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 management.)
+
+
+
+Shirey                       Informational                     [Page 96]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ key distribution center (KDC)
+      (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. (See: key translation center.)
+
+      (C) 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 sends that
+      encrypted set to Alice for her to forward to Bob, or sends it
+      directly to Bob (although the latter option is not supported in
+      the ANSI standard [A9017]).
+
+   $ key encapsulation
+      See: (secondary definition under) key recovery.
+
+   $ key-encrypting key (KEK)
+      (I) A cryptographic key that is used to encrypt other keys, either
+      DEKs or other KEKs, but usually is not used to encrypt application
+      data.
+
+   $ key escrow
+      See: (secondary definition under) key recovery.
+
+   $ key establishment (algorithm or protocol)
+      (I) A process that combines the key generation and key
+      distribution steps needed to set up or install a secure
+      communication association. (See: key agreement, key transport.)
+
+      (O) "The procedure to share a symmetric key among different
+      parties by either key agreement or key transport." [A9042]
+
+      (C) Key establishment involves either key agreement or key
+      transport:
+
+       - Key transport: One entity generates a secret key and securely
+         sends it to the other entity. (Or 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.)
+
+       - Key agreement: No secret is sent from one entity to another.
+         Instead, both entities, without prior arrangement except a
+         public exchange of data, compute the same secret value. I.e.,
+
+
+
+Shirey                       Informational                     [Page 97]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+         each can independently generate the same value, but that value
+         cannot be computed by other entities.
+
+   $ Key Exchange Algorithm (KEA)
+      (N) A key agreement algorithm [NIST] that is similar to the
+      Diffie-Hellman algorithm, uses 1024-bit asymmetric keys, and was
+      developed and formerly classified at the "Secret" level by NSA.
+      (See: CAPSTONE, CLIPPER, FORTEZZA, SKIPJACK.)
+
+      (C) 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 pseudo-random sequence of
+      cryptographic key values.
+
+      2. (I) An encryption device that incorporates a key generation
+      mechanism and applies the key to plaintext (e.g., by exclusive OR-
+      ing the key bit string with the plaintext bit string) to produce
+      ciphertext.
+
+   $ key length
+      (I) The number of symbols (usually bits) needed to be able to
+      represent any of the possible values of a cryptographic key. (See:
+      key space.)
+
+   $ key lifetime
+      (N) MISSI usage: 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 management
+      (I) The process of handling and controlling cryptographic keys and
+      related material (such as initialization values) during their life
+      cycle in a cryptographic system, including ordering, generating,
+      distributing, storing, loading, escrowing, archiving, auditing,
+      and destroying the material. (See: key distribution, key escrow,
+      keying material, public-key infrastructure.)
+
+      (O) "The generation, storage, distribution, deletion, archiving
+      and application of keys in accordance with a security policy."
+      [I7498 Part 2]
+
+
+
+Shirey                       Informational                     [Page 98]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (O) "The activities involving the handling of cryptographic keys
+      and other related security parameters (e.g., IVs, counters) during
+      the entire life cycle of the keys, including their generation,
+      storage, distribution, entry and use, deletion or destruction, and
+      archiving." [FP140]
+
+   $ 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.)
+
+   $ key material identifier (KMID)
+      (N) MISSI usage: 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.
+
+   $ 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 (e.g.,
+      see: Diffie-Hellman, Rivest-Shamir-Adleman).
+
+      (C) A key pair's owner discloses the public key to other system
+      entities so they can use the key to encrypt data, verify a digital
+      signature, compute a protected checksum, or generate a key in a
+      key agreement algorithm. The matching private key is kept secret
+      by the owner, who uses it to decrypt data, generate a digital
+      signature, verify a protected checksum, or generate a key in a key
+      agreement algorithm.
+
+   $ key recovery
+      1. (I) A process for learning the value of a cryptographic key
+      that was previously used to perform some cryptographic operation.
+      (See: cryptanalysis.)
+
+      2. (I) Techniques that provide an intentional, alternate (i.e.,
+      secondary) means to access the key used for data confidentiality
+      service in an encrypted association. [DOD4]
+
+      (C) We assume that the encryption mechanism has 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 escrow and key encapsulation:
+
+
+
+
+
+
+
+Shirey                       Informational                     [Page 99]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+       - "Key escrow": 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.
+
+         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 encapsulation": A key recovery technique for storing
+         knowledge of a cryptographic key by encrypting it with another
+         key and ensuring that that only certain third parties called
+         "recovery agents" can perform the decryption operation to
+         retrieve the stored key.
+
+         Key encapsulation typically allows direct retrieval of the
+         secret key used to provide data confidentiality.
+
+   $ 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 (used in a symmetric cryptography) that
+      implements a key distribution protocol to convey keys between two
+      (or more) parties who wish to communicate securely. (See: key
+      distribution center.)
+
+      (C) A key translation center translates 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 sends that encrypted set to Alice
+      for her to forward to Bob, or sends it directly to Bob (although
+      direct distribution is not supported in the ANSI standard
+      [A9017]).
+
+
+
+
+Shirey                       Informational                    [Page 100]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ key transport (algorithm or protocol)
+      (I) A key establishment method by which a secret key is generated
+      by one entity in a communication association and securely sent to
+      another entity in the association. (See: key agreement.)
+
+      (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]
+
+      (C) For example, a message originator can generate a random
+      session key and then use the Rivest-Shamir-Adleman algorithm to
+      encrypt that key with the public key of the intended recipient.
+
+   $ key update
+      (I) Derive a new key from an existing key. (See: certificate
+      rekey.)
+
+   $ key validation
+      (N) "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]
+
+   $ 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.)
+
+      (C) If the input data object is changed, a new 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 least two forms of keyed hash:
+
+       - A function based on a keyed encryption algorithm. (E.g., see:
+         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. (E.g., see: HMAC.)
+
+   $ keying material
+      (I) Data (such as keys, key pairs, and initialization values)
+      needed to establish and maintain a cryptographic security
+      association.
+
+
+
+
+
+Shirey                       Informational                    [Page 101]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ KMID
+      See: key 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 the
+      knowing the cryptographic algorithm).
+
+   $ L2F
+      See: Layer 2 Forwarding Protocol.
+
+   $ L2TP
+      See: Layer 2 Tunneling Protocol.
+
+   $ label
+      See: security label.
+
+   $ 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 model
+      (I) A security 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] (See: flow control, security
+      level, security model.)
+
+      (C) The model describes the semantic structure formed by a finite
+      set of security levels, such as those used in military
+      organizations.
+
+      (C) A lattice is 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. For 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 (X1, ..., Xm), and c
+      is a (possibly empty) subset of a finite set C of non-hierarchical
+      categories (C1, ..., Cn) -- together with the "dominate" relation.
+      (See: dominate.)
+
+   $ Law Enforcement Access Field (LEAF)
+      (N) A data item that is automatically embedded in data encrypted
+      by devices (e.g., see: CLIPPER chip) that implement the Escrowed
+      Encryption Standard.
+
+
+
+
+Shirey                       Informational                    [Page 102]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ 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: virtual private
+      network.)
+
+      (C) PPP can in turn encapsulate any OSI 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
+      See: Lightweight Directory Access Protocol.
+
+   $ 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. (See:
+      economy of mechanism.)
+
+      (C) This principle tends to limit damage that can be caused by an
+      accident, error, or unauthorized act.
+
+   $ Lightweight Directory Access Protocol (LDAP)
+      (N) A client-server protocol 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).
+      [R1777]
+
+      (C) 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
+      (I) World Wide Web usage: See: hyperlink.
+
+      (I) Subnetwork usage: A point-to-point communication channel
+      connecting two subnetwork relays (especially one between two
+      packet switches) that is implemented at OSI layer 2. (See: link
+      encryption.)
+
+
+
+
+Shirey                       Informational                    [Page 103]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (C) 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.
+
+   $ link-by-link encryption
+   $ link encryption
+      (I) Stepwise 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] (See: end-to-end encryption.)
+
+   $ 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
+      (I) The act of a system entity gaining access to a session in
+      which the entity can use system resources; usually accomplished by
+      providing a user name and password to an access control system
+      that authenticates the user.
+
+      (C) Derives from "log" file", a security audit trail that records
+      security events, such as the beginning of sessions, and who
+      initiates them.
+
+   $ LOTOS
+      See: Language of Temporal Ordering Specification.
+
+   $ MAC
+      See: mandatory access control, Message Authentication Code.
+
+   $ malicious logic
+      (I) Hardware, software, or firmware that is intentionally included
+      or inserted in a system for a harmful purpose. (See: logic bomb,
+      Trojan horse, virus, worm.)
+
+   $ malware
+      (I) A contraction of "malicious software". (See: malicious logic.)
+
+      (D) ISDs SHOULD NOT use this term because it is not listed in most
+      dictionaries and could confuse international readers.
+
+
+
+
+
+Shirey                       Informational                    [Page 104]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ man-in-the-middle
+      (I) A form of active wiretapping attack in which the attacker
+      intercepts and selectively modifies communicated data in order to
+      masquerade as one or more of the entities involved in a
+      communication association. (See: hijack attack, piggyback attack.)
+
+      (C) For example, suppose Alice and Bob try to establish a session
+      key by using the Diffie-Hellman 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 in
+      order to capture or modify sensitive information that Alice and
+      Bob think they are sending only to each other.
+
+   $ mandatory access control (MAC)
+      (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 system entities are eligible to access
+      certain resources). (See: discretionary access control, rule-based
+      security policy.)
+
+      (C) This kind of access control is called "mandatory" because an
+      entity that has clearance to access a resource may not, just by
+      its own volition, enable another entity to access that resource.
+
+      (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) ISDs SHOULD NOT use this term as a synonym for "checksum"
+      because 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 such
+      protection is not intended, use "error detection code" or some
+      specific type of checksum that is not protected.
+
+   $ masquerade attack
+      (I) A type of attack in which one system entity illegitimately
+      poses as (assumes the identity of) another entity. (See: spoofing
+      attack.)
+
+
+
+
+Shirey                       Informational                    [Page 105]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ MCA
+      See: merchant certificate 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. (See: message digest.)
+
+   $ MD4
+      (N) A cryptographic hash [R1320] that produces a 128-bit hash
+      result and was designed by Ron Rivest. (See: message digest and
+      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.
+
+   $ merchant
+      (O) SET usage: "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 usage: 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 usage: 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
+
+
+
+
+Shirey                       Informational                    [Page 106]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      relationships between CAs, the relationships are peer-to-peer, and
+      CAs issue cross-certificates to each other. (See: hierarchical
+      PKI, trust-file PKI.)
+
+   $ message authentication code vs. Message Authentication Code (MAC)
+      1. (N) Capitalized: "(The) Message Authentication Code" refers to
+      an ANSI standard for a checksum that is computed with a keyed hash
+      that is based on DES. [A9009] (Also known as the U.S. Government
+      standard Data Authentication Code. [FP113])
+
+      (C) The ANSI standard MAC algorithm is equivalent to cipher block
+      chaining with IV = 0.
+
+      2. (D) Not capitalized: ISDs SHOULD NOT use the uncapitalized form
+      "message authentication code", because this term mixes concepts in
+      a potentially misleading way. Instead, use "checksum", "error
+      detection code", "hash", "keyed hash", "Message Authentication
+      Code", or "protected checksum", depending on what is meant. (See:
+      authentication code.)
+
+      (C) In the uncapitalized form, 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, and 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) ISDs SHOULD NOT use this term as a synonym for "hash result"
+      because it unnecessarily duplicates the meaning of the other, more
+      general term and mixes concepts in a potentially misleading way.
+      (See: cryptographic hash, Message Handling System.)
+
+   $ Message Handling Systems
+      (I) A ITU-T/ISO system concept, which 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
+      (D) ISDs SHOULD NOT use this term as a synonym for "initialization
+      value" because it mixes concepts in a potentially misleading way.
+
+
+
+
+
+
+Shirey                       Informational                    [Page 107]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ message integrity check
+   $ message integrity code
+      (D) ISDs SHOULD NOT use these terms because they mix concepts in a
+      potentially misleading way. (The word "message" is misleading
+      because it suggests that the mechanism is particularly suitable
+      for or limited to electronic mail. The word "code" is misleading
+      because it suggests that either encoding or encryption is
+      involved, or that the term refers to computer software.) Instead,
+      use "checksum", "error detection code", "hash", "keyed hash",
+      "Message Authentication Code", or "protected checksum", depending
+      on what is meant.
+
+   $ 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. Defense Message System.
+
+   $ MHS
+      See: message handling system.
+
+   $ MIME
+      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. [MISPC]
+
+   $ MISPC
+      See: Minimum Interoperability Specification for PKI Components.
+
+   $ MISSI
+      (N) 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 Government missions. (See: MSP.)
+
+
+
+
+
+
+
+Shirey                       Informational                    [Page 108]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ MISSI user
+      (O) MISSI usage: 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.)
+
+      (C) 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. Some machines are required to
+      operate non-stop. To avoid downtime needed to exchange the
+      FORTEZZA cards of machine operators at shift changes, the machines
+      may be issued their own cards, as if they were persons.
+
+   $ mode
+   $ mode of operation
+      (I) Encryption usage: 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: electronic codebook, cipher block
+      chaining, cipher feedback, output feedback.)
+
+      (I) System operation usage: 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: dedicated
+      security mode, multilevel security mode, partitioned security
+      mode, system high security mode.)
+
+   $ 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, Rivest-Shamir-Adleman.)
+
+   $ Morris Worm
+      (I) A worm program written by Robert T. Morris, Jr. that flooded
+      the ARPANET in November, 1988, causing problems for thousands of
+      hosts. (See: worm.)
+
+   $ MOSS
+      See: MIME Object Security Services.
+
+   $ MSP
+      See: Message Security Protocol.
+
+   $ multilevel secure (MLS)
+      (I) A class of system that has system resources (particularly
+      stored information) at more than one security level (i.e., has
+      different types of sensitive resources) and that permits
+
+
+
+
+Shirey                       Informational                    [Page 109]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      concurrent access by users who differ in security clearance and
+      need-to-know, but is able to prevent each user from accessing
+      resources for which the user lacks authorization.
+
+   $ multilevel security mode
+      (I) A mode of operation of an information system, that allows two
+      or more classification levels of information to be processed
+      concurrently within the same system when not all users have a
+      clearance or formal access authorization for all data handled by
+      the system.
+
+      (C) This mode is defined formally in U.S. Department of Defense
+      policy regarding system accreditation [DOD2], but the term is also
+      used outside the Defense Department and outside the Government.
+
+   $ Multipurpose Internet Mail Extensions (MIME)
+      (I) An Internet protocol [R2045] that enhances the basic format of
+      Internet electronic mail messages [R0822] to be able to use
+      character sets other than US-ASCII for textual headers and text
+      content, and 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.
+
+   $ National Computer Security Center (NCSC)
+      (N) A U.S. Department of Defense organization, housed in NSA, that
+      has responsibility for encouraging widespread availability of
+      trusted computer systems throughout the Federal Government. It has
+      established criteria for, and performs evaluations of, computer
+      and network systems that have a trusted computing base. (See:
+      Evaluated Products List, Rainbow Series, TCSEC.)
+
+   $ National Information Assurance Partnership (NIAP)
+      (N) An organization created by 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.
+
+      (C) NIAP is registered, through the U.S. Department of Defense, 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.
+
+
+
+Shirey                       Informational                    [Page 110]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+       - 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 agency that promotes U.S.
+      economic growth by working with industry to develop and apply
+      technology, measurements, and standards. Has primary Government
+      responsibility for INFOSEC standards for unclassified but
+      sensitive information. (See: ANSI, DES, DSA, DSS, FIPS, NIAP,
+      NSA.)
+
+   $ National Security Agency (NSA)
+      (N) A U.S. Department of Defense intelligence agency that has
+      primary Government responsibility for INFOSEC for classified
+      information and for unclassified but sensitive information handled
+      by national security systems. (See: FORTEZZA, KEA, MISSI, NIAP,
+      NIST, SKIPJACK.)
+
+   $ need-to-know
+      (I) The necessity for access to, knowledge of, or possession of
+      specific information required to carry out official duties.
+
+      (C) This 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
+      See: computer network.
+
+   $ NIAP
+      See: National Information Assurance Partnership.
+
+   $ NIST
+      See: National Institute of Standards and Technology.
+
+   $ NLSP
+      Network Layer Security Protocol. An OSI protocol (IS0 11577) for
+      end-to-end encryption services at the top of OSI layer 3. NLSP is
+      derived from an SDNS protocol, SP3, but is much more complex.
+
+
+
+Shirey                       Informational                    [Page 111]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ no-lone zone
+      (I) A room or other space to which no person may have
+      unaccompanied access and that, when occupied, is required to be
+      occupied by two or more appropriately authorized persons. (See:
+      dual control.)
+
+   $ 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.
+
+   $ non-critical
+      See: critical (extension of certificate).
+
+   $ non-repudiation service
+      (I) A security service that provide protection against false
+      denial of involvement in a communication. (See: repudiation.)
+
+      (C) Non-repudiation service does not and cannot 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. There are two basic
+      kinds of non-repudiation service:
+
+       - "Non-repudiation with proof of origin" 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. This service can
+         be viewed as a stronger version of an data origin
+         authentication service, in that it proves authenticity to a
+         third party.
+
+       - "Non-repudiation with proof of receipt" 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.
+
+      (C) Phases of a Non-Repudiation Service: Ford [For94, For97] uses
+      the term "critical action" to refer to the act of communication
+      that is the subject of the service:
+
+
+
+
+
+
+
+
+
+
+Shirey                       Informational                    [Page 112]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      --------   --------   --------   --------   --------   . --------
+      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. Before the critical action, the service requester asks, either
+         implicitly or explicitly, to have evidence of the action be
+         generated.
+      2. When the critical action occurs, evidence is generated by a
+         process involving the potential repudiator and possibly also a
+         trusted third party.
+      3. The evidence is transferred to the requester, or stored by a
+         third party, for later use if needed.
+      4. The entity that holds the evidence tests to be sure that it
+         will suffice if a dispute arises.
+      5. The evidence is retained for possible future retrieval and use.
+      6. 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.
+
+   $ no-PIN ORA (NORA)
+      (O) MISSI usage: 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.
+
+   $ NORA
+      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, and delivery. [I7498 Part 2] (See:
+      digital notary.)
+
+
+
+
+Shirey                       Informational                    [Page 113]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ NULL encryption algorithm
+      (I) An algorithm [R2410] that does nothing to transform plaintext
+      data; i.e., a no-op. It originated because of IPsec ESP, which
+      always specifies the use of an encryption algorithm to provide
+      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 this is needed).
+
+   $ OAKLEY
+      (I) A key establishment protocol (proposed for IPsec but
+      superseded by IKE) based on the Diffie-Hellman algorithm and
+      designed to be a compatible component of ISAKMP. [R2412]
+
+      (C) OAKLEY establishes a shared key with an assigned identifier
+      and associated authenticated identities for parties. I.e., OAKLEY
+      provides authentication service to ensure the entities of each
+      other's identity, even if the Diffie-Hellman exchange is
+      threatened by active wiretapping. Also, 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.
+
+   $ object
+      (I) Trusted computer system modeling usage: A system element that
+      contains or receives information. (See: Bell-LaPadula Model,
+      trusted computer system.)
+
+   $ object identifier (OID)
+      (I) 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.
+
+      (O) "A value (distinguishable from all other such values) which is
+      associated with an object." [X680]
+
+      (C) 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.
+
+      (C) 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
+
+
+
+Shirey                       Informational                    [Page 114]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      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}.
+
+      (C) The following are additional examples: ANSI registers
+      organization names below the branch {joint-iso-ccitt(2)
+      country(16) US(840) organization(1)}. The NIST CSOR records PKI
+      objects below the branch {joint-iso-ccitt(2) country(16) us(840)
+      gov(101) csor(3) pki(4)}. The U.S. Department of Defense registers
+      INFOSEC objects below the branch {joint-iso-ccitt(2) country(16)
+      us(840) organization(1) gov(101) dod(2) infosec(1)}. The OID for
+      the PKIX private extension is defined in an arc below the arc for
+      the PKIX name space, as {iso(1) identified-organization(3) dod(6)
+      internet(1) security(5) mechanisms(5) pkix(7) 1 1}.
+
+   $ object reuse
+      (N) "The reassignment and reuse of a storage medium (e.g., page
+      frame, disk sector, magnetic tape) that once contained one or more
+      [information] objects. To be securely reused and assigned to a new
+      subject, storage media must contain no residual data (magnetic
+      remanence) from the object(s) previously contained in the media."
+      [NCS04]
+
+   $ OCSP
+      See: On-line Certificate Status Protocol.
+
+   $ octet
+      (I) A data unit of eight bits. (See: byte.)
+
+      (c) 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.
+
+   $ OFB
+      See: output feedback.
+
+   $ ohnosecond
+      (C) That minuscule fraction of time in which you realize that your
+      private key has been compromised.
+
+   $ OID
+      See: object identifier.
+
+
+
+
+
+Shirey                       Informational                    [Page 115]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ On-line Certificate Status Protocol (OCSP)
+      (I) An Internet protocol used by a client to obtain from a server
+      the validity status and other information concerning a digital
+      certificate.
+
+      (C) In some applications, such as those involving high-value
+      commercial transactions, it may be necessary to obtain certificate
+      revocation status that is more timely than is possible with CRLs
+      or 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
+      (I) An encryption algorithm in which the key is a random sequence
+      of symbols and each symbol is used for encryption only one time--
+      to encrypt only one plaintext symbol to produce only one
+      ciphertext symbol--and a copy of the key is used similarly for
+      decryption.
+
+      (C) 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. 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. Capitalized: "One-Time Password" is an Internet protocol
+      [R1938] 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.
+
+   $ one-way encryption
+      (I) Irreversible transformation of plaintext to ciphertext, such
+      that the plaintext cannot be recovered from the ciphertext by
+      other than exhaustive procedures even if the cryptographic key is
+      known. (See: encryption.)
+
+
+
+Shirey                       Informational                    [Page 116]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ one-way function
+      (I) "A (mathematical) function, f, which 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]
+
+      (D) ISDs SHOULD NOT use this term as a synonym for "cryptographic
+      hash".
+
+   $ open security environment
+      (O) U.S. Department of Defense usage: A system environment that
+      meets at least one of the following 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: closed security environment.)
+
+   $ Open Systems Interconnection (OSI) Reference Model (OSIRM)
+      (N) A joint ISO/ITU-T standard [I7498 Part 1] for a seven-layer,
+      architectural communication framework for interconnection of
+      computers in networks.
+
+      (C) OSI-based standards include communication protocols that are
+      mostly incompatible with the Internet Protocol Suite, but also
+      include security models, such as X.509, that are used in the
+      Internet.
+
+      (C) The OSIRM layers, from highest to lowest, are (7) Application,
+      (6) Presentation, (5) Session, (4) Transport, (3) Network, (2)
+      Data Link, and (1) Physical. In this Glossary, these layers are
+      referred to by number to avoid confusing them with Internet
+      Protocol Suite layers, which are referred to by name.
+
+      (C) Some unknown person described how the OSI layers correspond to
+      the seven deadly sins:
+
+      7. Wrath: Application is always angry at 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.)
+
+
+
+Shirey                       Informational                    [Page 117]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      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.
+
+      (C) John G. Fletcher described how the OSI layers also correspond
+      to Snow White's dwarf friends:
+
+      7. Doc: Application acts as if it is in charge, but sometimes
+         muddles its syntax.
+      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) A synonym for "system integrity"; emphasizes the actual
+      performance of system functions rather than just the ability to
+      perform them.
+
+   $ 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.
+
+   $ OPSEC
+      See: operations security.
+
+   $ ORA
+      See: organizational registration authority.
+
+   $ Orange Book
+      (D) ISDs SHOULD NOT use this term as a synonym for "Trusted
+      Computer System Evaluation Criteria" [CSC001, DOD1]. Instead, use
+
+
+
+
+
+Shirey                       Informational                    [Page 118]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      the full, proper name of the document or, in subsequent
+      references, the abbreviation "TCSEC". (See: (usage note under)
+      Green Book.)
+
+   $ organizational certificate
+      (O) MISSI usage: A type of MISSI X.509 public-key certificate that
+      is issued to support organizational message handling for the U.S.
+      Government's Defense Message System.
+
+   $ organizational registration authority (ORA)
+      (I) General usage: An RA for an organization.
+
+      (O) MISSI usage: The MISSI implementation of RA. A MISSI 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 office or role, and to
+      the person who fills that office. An ORA does not sign
+      certificates, CRLs, or CKLs. (See: no-PIN ORA, SSO-PIN ORA, user-
+      PIN ORA.)
+
+   $ origin authentication
+   $ origin authenticity
+      (D) ISDs SHOULD NOT use these terms because they look like
+      careless use of an internationally standardized term. Instead, use
+      "data origin authentication" or "peer entity authentication",
+      depending which is meant.
+
+   $ OSI
+   $ OSIRM
+      See: Open Systems Interconnection Reference Model.
+
+   $ OTP
+      See: One-Time Password.
+
+   $ out of band
+      (I) Transfer of information using a channel that is outside (i.e.,
+      separate from) the channel that is normally used. (See: covert
+      channel.)
+
+      (C) 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. (See: key distribution.)
+
+
+
+
+
+Shirey                       Informational                    [Page 119]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ output feedback (OFB)
+      (N) A block cipher mode [FP081] that modifies electronic codebook
+      mode to operate on plaintext segments of variable length less than
+      or equal to the block length.
+
+      (C) 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
+   $ outsider attack
+      See: (secondary definition under) attack.
+
+   $ P1363
+      See: IEEE P1363.
+
+   $ PAA
+      See: policy approving authority.
+
+   $ packet filter
+      See: (secondary definition under) filtering router.
+
+   $ pagejacking
+      (I) 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.
+
+      (D) ISDs SHOULD NOT use this term without including a definition,
+      because the term is not listed in most dictionaries and could
+      confuse international readers. (See: (usage note under) Green
+      Book.)
+
+   $ PAN
+      See: primary account number.
+
+   $ PAP
+      See: Password Authentication Protocol.
+
+
+
+
+
+
+
+
+Shirey                       Informational                    [Page 120]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ partitioned security mode
+      (N) A mode of operation of an information system, wherein all
+      users have the clearance, but not necessarily formal access
+      authorization and need-to-know, for all information handled by the
+      system. This mode is defined in U.S. Department of Defense policy
+      regarding system accreditation. [DoD2]
+
+   $ passive attack
+      See: (secondary definition under) attack.
+
+   $ passive wiretapping
+      See: (secondary definition under) wiretapping.
+
+   $ password
+      (I) A secret data value, usually a character string, that is used
+      as authentication information. (See: challenge-response.)
+
+      (C) A password is usually matched with a user identifier that is
+      explicitly presented in the authentication process, but in some
+      cases the identity may be implicit.
+
+      (C) Using a password as authentication information assumes that
+      the password is known only by the system entity whose 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 as
+      cleartext 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. [R1334]
+      (See: CHAP.)
+
+   $ password sniffing
+      (I) Passive wiretapping, usually on a local area network, to gain
+      knowledge of passwords. (See: (usage note 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.)
+
+
+
+Shirey                       Informational                    [Page 121]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ payment card
+      (N) SET usage: 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 usage: A system operated by an acquirer, or a third party
+      designated by an acquirer, for the purpose of providing 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 usage: 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.)
+
+      (C) The international PC Card Standard defines a non-proprietary
+      form factor in three standard 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) ISDs SHOULD NOT use this acronym without a qualifying
+      adjective because that would be ambiguous. (See: Internet policy
+      certification authority, (MISSI) policy creation authority, (SET)
+      payment gateway certification authority.)
+
+   $ 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.)
+
+
+
+
+Shirey                       Informational                    [Page 122]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ peer entity authentication
+      (I) "The corroboration that a peer entity in an association is the
+      one claimed." [I7498 Part 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.)
+
+      (C) 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.
+
+      (C) See: "relationship between data integrity service and
+      authentication services" under data integrity service.
+
+   $ PEM
+      See: Privacy Enhanced Mail.
+
+   $ penetration
+      (I) Successful, repeatable, unauthorized access to a protected
+      system resource. (See: attack, violation.)
+
+   $ penetration test
+      (I) A system test, often part of system certification, in which
+      evaluators attempt to circumvent the security features of the
+      system. [NCS04]
+
+      (C) Penetration testing may be performed under various constraints
+      and conditions. However, 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
+      See: (discussion under) public-key forward secrecy.
+
+   $ perimeter
+      See: security perimeter.
+
+
+
+
+
+
+
+Shirey                       Informational                    [Page 123]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ 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.)
+
+   $ permission
+      (I) A synonym for "authorization", but "authorization" is
+      preferred in the PKI context. (See: privilege.)
+
+   $ personal identification number (PIN)
+      (I) A character string used as a password to gain access to a
+      system resource. (See: authentication information.)
+
+      (C) Despite the words "identification" and "number", a PIN seldom
+      serves as a user identifier, and a PIN's characters are not
+      necessarily all numeric. A better name for this concept would have
+      been "personal authentication system string (PASS)".
+
+      (C) Retail banking applications commonly use 4-digit PINs.
+      FORTEZZA PC card's use up to 12 characters for user or SSO PINs.
+
+   $ personality
+   $ personality label
+      (O) MISSI usage: 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.
+
+      (C) When a card's user selects a personality to use in a FORTEZZA-
+      aware application, the data determines behavior traits (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 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.
+
+
+
+
+
+Shirey                       Informational                    [Page 124]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ PGP(trademark)
+      See: Pretty Good Privacy.
+
+   $ Photuris
+      (I) A UDP-based, key establishment protocol for session keys,
+      designed for use with the IPsec protocols AH and ESP. Superseded
+      by IKE.
+
+   $ phreaking
+      (I) A contraction of "telephone breaking". An attack on or
+      penetration of a telephone system or, by extension, any other
+      communication or information system. [Raym]
+
+      (D) ISDs SHOULD NOT use this term because it is not listed in most
+      dictionaries and could confuse international readers.
+
+   $ physical security
+      (I) Tangible means of preventing unauthorized physical access to a
+      system. E.g., fences, walls, and other barriers; locks, safes, and
+      vaults; dogs and armed guards; sensors and alarm bells. [FP031,
+      R1455]
+
+   $ 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.)
+
+   $ PIN
+      See: personal identification number.
+
+   $ ping of death
+      (I) An attack that sends an improperly large ICMP [R0792] echo
+      request packet (a "ping") with the intent of overflowing the input
+      buffers of the destination machine and causing it to crash.
+
+   $ ping sweep
+      (I) An attack that sends ICMP [R0792] echo requests ("pings") to a
+      range of IP addresses, with the goal of finding hosts that can be
+      probed for vulnerabilities.
+
+   $ PKCS
+      See: Public-Key Cryptography Standards.
+
+   $ PKCS #7
+      (N) A standard [PKC07, R2315] from the PKCS series; defines a
+      syntax for data that may have cryptography applied to it, such as
+      for digital signatures and digital envelopes.
+
+
+
+Shirey                       Informational                    [Page 125]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ PKCS #10
+      (N) A standard [PKC10] from the PKCS series; defines a syntax for
+      requests for public-key certificates. (See: certification
+      request.)
+
+      (C) 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 a software
+      CAPI called Cryptoki (pronounced "crypto-key"; short for
+      "cryptographic token interface") for devices that hold
+      cryptographic information and perform cryptographic functions.
+
+   $ PKI
+      See: public-key infrastructure.
+
+   $ PKIX
+      (I) (1.) A contraction of "Public-Key Infrastructure (X.509)", the
+      name of the IETF working group that is specifying an architecture
+      and set of protocols needed to support an X.509-based PKI for the
+      Internet. (2.) A collective name for that architecture and set of
+      protocols.
+
+      (C) 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.
+
+   $ PKIX private extension
+      (I) PKIX defines a private extension to identify an on-line
+      verification service supporting the issuing CA.
+
+
+
+
+
+
+Shirey                       Informational                    [Page 126]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ plaintext
+      (I) Data that is input to and transformed by an encryption
+      process, or that is output by a decryption process.
+
+      (C) Usually, the plaintext input to an encryption operation is
+      cleartext. But in some cases, the input is ciphertext that was
+      output from another encryption operation. (See: superencryption.)
+
+   $ Point-to-Point Protocol (PPP)
+      (I) An Internet Standard protocol [R1661] for encapsulation and
+      full-duplex transportation of network layer (mainly OSI layer 3)
+      protocol data packets over a link between two peers, and for
+      multiplexing different network layer 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 network layer data. (See: CHAP, EAP, PAP.)
+
+   $ Point-to-Point Tunneling Protocol (PPTP)
+      (I) An Internet client-server protocol (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.)
+
+      (C) PPP can encapsulate any Internet Protocol Suite network layer
+      protocol (or OSI 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., the PPTP Network Server, which runs on a general-purpose
+      host).
+
+   $ policy
+      (D) ISDs SHOULD NOT use this word as an abbreviation for either
+      "security policy" or "certificate policy". Instead, to avoid
+      misunderstanding, use the fully qualified term, at least at the
+      point of first usage.
+
+   $ policy approving authority (PAA)
+      (O) MISSI usage: 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: root registry.)
+
+
+
+
+
+
+Shirey                       Informational                    [Page 127]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (C) A PAA registers MISSI PCAs and signs their X.509 public-key
+      certificates. A PAA issues CRLs but does not issue a CKL. A PAA
+      may issue cross-certificates to other PAAs.
+
+   $ policy certification authority (Internet PCA)
+      (I) An X.509-compliant CA at the second level of the Internet
+      certification hierarchy, under the Internet Policy Registration
+      Authority (IPRA). Each PCA operates in accordance with its
+      published security policy (see: certification practice statement)
+      and within constraints established by the IPRA for all PCAs.
+      [R1422]. (See: policy creation authority.)
+
+   $ policy creation authority (MISSI PCA)
+      (O) MISSI usage: 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.)
+
+      (C) A MISSI PCA's certificate is issued by a policy approving
+      authority. 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
+      (N) Canadian usage: An organization responsible for PKI oversight
+      and policy management in the Government of Canada.
+
+   $ 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]
+
+   $ POP3
+      See: Post Office Protocol, version 3.
+
+   $ POP3 APOP
+      (I) A POP3 "command" (better described as a transaction type, or a
+      protocol-within-a-protocol) 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.)
+
+
+
+
+Shirey                       Informational                    [Page 128]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (C) The server includes a unique timestamp 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 timestamp and a shared secret
+      that is known only to the client and the server. APOP was designed
+      to provide as 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 "command" [R1734] (better described as a transaction type,
+      or a protocol-within-a-protocol) in POP3, 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.)
+
+      (C) 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 used by POP3 AUTH are those
+      used by IMAP4.
+
+   $ port scan
+      (I) An attack that sends client requests to a range of server port
+      addresses on a host, with the goal of finding an active port and
+      exploiting a known vulnerability of that service.
+
+   $ POSIX
+      (N) Portable Operating System Interface for Computer Environments,
+      a standard [FP151, IS9945-1] (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.
+
+      (C) P1003.1 supports security functionality like those on most
+      UNIX systems, including discretionary access control and
+      privilege. IEEE Draft Standard P1003.6.1 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 [R1939] 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.)
+
+
+
+Shirey                       Informational                    [Page 129]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (C) POP3 has mechanisms for optionally authenticating a client to
+      a server and providing other security services. (See: POP3 APOP,
+      POP3 AUTH.)
+
+   $ PPP
+      See: Point-to-Point Protocol.
+
+   $ PPTP
+      See: Point-to-Point Tunneling Protocol.
+
+   $ pre-authorization
+      (I) A capability of a CAW that enables certification requests to
+      be automatically validated against data provided in advance to the
+      CA by an authorizing entity.
+
+   $ 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. (See: MOSS, PEM, S/MIME.)
+
+      (C) PGP encrypts messages with IDEA in CFB mode, distributes the
+      IDEA keys by encrypting them with RSA, and creates digital
+      signatures on messages with MD5 and RSA. To establish ownership of
+      public keys, PGP depends on the web of trust. (See: Privacy
+      Enhanced Mail.)
+
+   $ primary account number (PAN)
+      (O) SET usage: "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, IS7812] (See: bank identification number.)
+
+      (C) 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 bank identification number part of the
+      PAN is the American Bankers Association.
+
+   $ privacy
+      (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 information about itself with others. (See: anonymity.)
+
+
+
+
+
+Shirey                       Informational                    [Page 130]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (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 Part
+      2]
+
+      (D) ISDs 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.
+
+   $ Privacy Enhanced Mail (PEM)
+      (I) An Internet protocol to provide data confidentiality, data
+      integrity, and data origin authentication for electronic mail.
+      [R1421, R1422]. (See: MOSS, MSP, PGP, S/MIME.)
+
+      (C) PEM encrypts messages with DES in CBC mode, provides key
+      distribution of DES keys by encrypting them with RSA, and signs
+      messages with 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 RSA
+      and MD2. (See: Pretty Good Privacy.)
+
+      (C) 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) A synonym for "private key".
+
+      (D) In most cases, ISDs SHOULD NOT use this term; to avoid
+      confusing readers, use "private key" instead. However, the term
+      MAY be used when specifically discussing a key pair; e.g., "A key
+      pair has a public component and a private component."
+
+   $ private extension
+      See: (secondary definition under) extension.
+
+   $ private key
+      (I) The secret component of a pair of cryptographic keys used for
+      asymmetric cryptography. (See: key pair, public key.)
+
+      (O) "(In a public key cryptosystem) that key of a user's key pair
+      which is known only by that user." [X509]
+
+
+
+Shirey                       Informational                    [Page 131]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ privilege
+      (I) An authorization or set of authorizations to perform security-
+      relevant functions, especially in the context of a computer
+      operating system.
+
+   $ privilege management infrastructure
+      (N) "The complete set of processes required to provide an
+      authorization service", i.e., processes concerned with attribute
+      certificates. [FPDAM] (See: PKI.)
+
+      (D) ISDs SHOULD NOT use this term and its definition because the
+      definition is vague, and there is no consensus on an alternate
+      definition.
+
+   $ privileged process
+      (I) An computer process that is authorized (and, therefore,
+      trusted) to perform some security-relevant functions that ordinary
+      processes are not. (See: privilege, trusted process.)
+
+   $ procedural security
+      (D) ISDs SHOULD NOT use this term as a synonym for "administrative
+      security". Any type of security may involve procedures; 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.)
+
+   $ 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, (discussion under) checksum.
+
+   $ protected distribution system
+      (I) A wireline or fiber-optic system that includes sufficient
+      safeguards (acoustic, electric, electromagnetic, and physical) to
+      permit its use for unencrypted transmission of (cleartext) data.
+
+   $ protection authority
+      See: (secondary definition under) Internet Protocol Security
+      Option.
+
+
+
+
+
+Shirey                       Informational                    [Page 132]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ 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.
+
+   $ protocol
+      (I) A set of rules (i.e., formats and procedures) to implement and
+      control some type of association (e.g., communication) between
+      systems. (E.g., see: Internet Protocol.)
+
+      (C) In particular, a series of ordered steps involving computing
+      and communication that are performed by two or more system
+      entities to achieve a joint objective. [A9042]
+
+   $ protocol suite
+      (I) A complementary collection of communication protocols used in
+      a computer network. (See: Internet, OSI.)
+
+   $ proxy server
+      (I) A computer process--often used as, or as part of, a firewall--
+      that relays 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.)
+
+      (C) In a firewall, a proxy server usually runs on a bastion host,
+      which may support proxies for several 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 remote 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.
+
+      (C) 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 capability. A proxy at OSI
+      layer 7 can also provide finer-grained security service than can a
+      filtering router at OSI layer 3. For example, an FTP proxy could
+      permit transfers out of, but not into, a protected network.
+
+
+
+
+
+
+Shirey                       Informational                    [Page 133]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ pseudo-random
+      (I) A sequence of values that appears to be random (i.e.,
+      unpredictable) but is actually generated by a deterministic
+      algorithm. (See: random.)
+
+   $ pseudo-random number generator
+      (I) A process used to deterministically generate a series of
+      numbers (usually integers) that appear to be random according to
+      certain statistical tests, but actually are pseudo-random.
+
+      (C) Pseudo-random number generators are usually implemented in
+      software.
+
+   $ public component
+      (I) A synonym for "public key".
+
+      (D) In most cases, ISDs SHOULD NOT use this term; to avoid
+      confusing readers, use "private key" instead. However, the term
+      MAY be used when specifically discussing a key pair; e.g., "A key
+      pair has a public component and a private component."
+
+   $ public key
+      (I) The publicly-disclosable component of a pair of cryptographic
+      keys used for asymmetric cryptography. (See: key pair, private
+      key.)
+
+      (O) "(In a public key cryptosystem) that key of a user's key pair
+      which is publicly known." [X509]
+
+   $ public-key certificate
+      (I) A digital certificate that binds a system entity's identity to
+      a public key value, and possibly to additional data items; a
+      digitally-signed data structure that attests to the ownership of a
+      public key. (See: X.509 public-key certificate.)
+
+      (C) 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.
+
+      (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]
+
+   $ public-key cryptography
+      (I) The popular synonym for "asymmetric cryptography".
+
+
+
+
+
+Shirey                       Informational                    [Page 134]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ Public-Key Cryptography Standards (PKCS)
+      (I) A series of specifications published by RSA Laboratories for
+      data structures and algorithm usage for basic applications of
+      asymmetric cryptography. (See: PKCS #7, PKCS #10, PKCS #11.)
+
+      (C) 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.
+
+      (C) Some existing RFCs use the term "perfect forward secrecy" but
+      either do not define it or do not define it precisely. While
+      preparing this Glossary, we tried to find a good definition for
+      that term, but 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 algorithm. The term
+      "public-key forward secrecy" (suggested by Hilarie Orman) and the
+      "I" definition stated for it here were crafted to be compatible
+      with current Internet documents, yet be narrow and leave room for
+      improved terminology.
+
+      (C) Challenge to the Internet security community: We need a
+      taxonomy--a family of mutually exclusive and collectively
+      exhaustive terms and definitions to cover the basic properties
+      discussed here--for the full range of cryptographic algorithms and
+      protocols used in Internet Standards:
+
+      (C) 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 135]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+       - 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.
+
+      (C) 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.
+
+      (C) 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.
+
+      (C) 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.
+
+      (C) Acknowledgements: Bill Burr, Burt Kaliski, Steve Kent, Paul
+      Van Oorschot, Michael Wiener, and, especially, Hilarie Orman
+      contributed ideas to this discussion.
+
+   $ public-key infrastructure (PKI)
+      (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
+
+
+
+
+Shirey                       Informational                    [Page 136]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      management functions for a community of users in an application of
+      asymmetric cryptography. (See: hierarchical PKI, mesh PKI,
+      security management infrastructure, trust-file PKI.)
+
+      (O) PKIX usage: The set of hardware, software, people, policies,
+      and procedures needed to create, manage, store, distribute, and
+      revoke digital certificates based on asymmetric cryptography.
+
+      (C) 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.
+
+      (C) A number of other servers and agents may support the core PKI,
+      and PKI clients may obtain services from them. 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, and time stamp agent.
+
+   $ RA
+      See: registration authority.
+
+   $ RA domains
+      (I) A capability of a CAW that allows a CA to divide the
+      responsibility for certification requests among multiple RAs.
+
+      (C) This capability might be used to restrict access to private
+      authorization data that is provided with a certification request,
+      and to distribute the responsibility to review and approve
+      certification requests in high volume environments. RA domains
+      might segregate certification requests according to an attribute
+      of the certificate subject, such as an organizational unit.
+
+   $ RADIUS
+      See: Remote Authentication Dial-In User Service.
+
+
+
+
+
+
+Shirey                       Informational                    [Page 137]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ Rainbow Series
+      (O) 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) General usage: In mathematics, random means "unpredictable". A
+      sequence of values is called random if each successive value is
+      obtained merely by chance and does not depend on the preceding
+      values of the sequence, and a selected individual value is called
+      random if each of the values in the total population of
+      possibilities has equal probability of being selected. [Knuth]
+      (See: cryptographic key, pseudo-random, random number generator.)
+
+      (I) Security usage: In cryptography and other security
+      applications, random means not only unpredictable, but also
+      "unguessable". When selecting data values to use for cryptographic
+      keys, "the requirement is for data that an adversary has a very
+      low probability of guessing or determining." It is not sufficient
+      to use data that "only meets traditional statistical tests for
+      randomness or which is based on limited range sources, such as
+      clocks. Frequently such random quantities are determinable [i.e.,
+      guessable] by an adversary searching through an embarrassingly
+      small space of possibilities." [R1750]
+
+   $ random number generator
+      (I) A process used to generate an unpredictable, uniformly
+      distributed series of numbers (usually integers). (See: pseudo-
+      random, random.)
+
+      (C) True random number generators are hardware-based devices that
+      depend on the output of a "noisy diode" or other physical
+      phenomena. [R1750]
+
+   $ RBAC
+      See: Role-Based Access Control.
+
+   $ RC2
+   $ RC4
+      See: Rivest Cipher #2, Rivest Cipher #4.
+
+   $ realm
+      (O) Kerberos usage: The domain of authority of a Kerberos server
+      (consisting of an authentication server and a ticket-granting
+      server), including the Kerberized clients and the Kerberized
+      application servers
+
+
+
+
+Shirey                       Informational                    [Page 138]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ RED
+      (I) Designation for information system equipment or facilities
+      that handle (and for data that contains) only plaintext (or,
+      depending on the context, classified information), and for such
+      data itself. This term derives from U.S. Government COMSEC
+      terminology. (See: BLACK, RED/BLACK separation.)
+
+   $ Red Book
+      (D) ISDs SHOULD NOT use this term as a synonym for "Trusted
+      Network Interpretation of the Trusted Computer System Evaluation
+      Criteria" [NCS05]. Instead, use the full proper name of the
+      document or, in subsequent references, a more conventional
+      abbreviation. (See: TCSEC, Rainbow Series, (usage note under)
+      Green Book.)
+
+   $ RED/BLACK separation
+      (I) An architectural concept for cryptographic systems that
+      strictly separates the parts of a system that handle plaintext
+      (i.e., RED information) from the parts that handle ciphertext
+      (i.e., BLACK information). This term derives from U.S. Government
+      COMSEC terminology. (See: BLACK, RED.)
+
+   $ 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.)
+
+      (C) 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) A type of replay attack in which transmitted data is sent back
+      to its originator.
+
+   $ register
+   $ registration
+      (I) 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.)
+
+      (C) 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
+
+
+
+Shirey                       Informational                    [Page 139]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      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 authenticating the entity's identity and
+      verifying the correctness of the other attributes, in accordance
+      with the CA's CPS.
+
+      (C) Among the registration issues that a CPS may address are the
+      following [R2527]:
+
+       - 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.
+       - 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)
+      (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: organizational registration authority,
+      registration.)
+
+      (C) 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
+      component, separate from the CA, that is assigned secondary
+      functions. The duties assigned to RAs vary from case to case but
+      may include the following:
+
+
+
+
+
+Shirey                       Informational                    [Page 140]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+       - 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, and handling
+         revocation reports. (Such functions may be assigned to a PKI
+         element that is separate from both the CA and the RA.)
+
+      (I) PKIX usage: 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. [R2510]
+
+      (O) SET usage: "An independent third-party organization that
+      processes payment card applications for multiple payment card
+      brands and forwards applications to the appropriate financial
+      institutions." [SET2]
+
+   $ regrade
+      (I) Deliberately change the classification level of information in
+      an authorized manner.
+
+   $ rekey
+      (I) Change the value of a cryptographic key that is being used in
+      an application of a cryptographic system. (See: certificate
+      rekey.)
+
+      (C) For example, 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. (See:
+      availability, survivability.)
+
+   $ relying party
+      (N) A synonym for "certificate user". Used in a legal context to
+      mean a recipient of a certificate who acts in reliance on that
+      certificate. (See: ABA Guidelines.)
+
+   $ Remote Authentication Dial-In User Service (RADIUS)
+      (I) An Internet protocol [R2138] for carrying dial-in users'
+      authentication information and configuration information between a
+
+
+
+Shirey                       Informational                    [Page 141]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      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.)
+
+      (C) A user of the RADIUS client presents authentication
+      information to the client, and the client passes that information
+      to the RADIUS server. The server authenticates the client using a
+      shared secret value, then checks the user's authentication
+      information, and finally returns to the client all authorization
+      and configuration information needed by the client to deliver
+      service to the user.
+
+   $ renew
+      See: certificate renewal.
+
+   $ replay attack
+      (I) An attack in which a valid data transmission is maliciously or
+      fraudulently repeated, either by the originator or by an adversary
+      who intercepts the data and retransmits it, possibly as part of a
+      masquerade attack. (See: active wiretapping.)
+
+   $ repository
+      (I) A system for storing and distributing digital certificates and
+      related information (including CRLs, CPSs, and certificate
+      policies) to certificate users. (See: directory.)
+
+      (O) "A trustworthy system for storing and retrieving certificates
+      or other information relevant to certificates." [ABA]
+
+      (C) 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 Federal Public-key
+      Infrastructure, for example, the expected repository is a
+      directory that uses LDAP, but also may be the X.500 Directory that
+      uses DAP, or an HTTP server, or an FTP server that permits
+      anonymous login.
+
+   $ repudiation
+      (I) Denial by a system entity that was involved in an association
+      (especially an association that transfers information) of having
+      participated in the relationship. (See: accountability, non-
+      repudiation service.)
+
+      (O) "Denial by one of the entities involved in a communication of
+      having participated in all or part of the communication." [I7498
+      Part 2]
+
+
+
+
+
+Shirey                       Informational                    [Page 142]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ Request for Comment (RFC)
+      (I) One of the documents in the archival series that is the
+      official channel for ISDs and other publications of the Internet
+      Engineering Steering Group, the Internet Architecture Board, and
+      the Internet community in general. [R2026, R2223] (See: Internet
+      Standard.)
+
+      (C) This term is *not* a synonym for "Internet Standard".
+
+   $ residual risk
+      (I) The risk that remains after countermeasures have been applied.
+
+   $ restore
+      See: card restore.
+
+   $ revocation
+      See: certificate revocation.
+
+   $ revocation date
+      (N) In an X.509 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.)
+
+      (C) 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 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
+      See: certificate revocation.
+
+   $ RFC
+      See: Request for Comment.
+
+   $ risk
+      (I) An expectation of loss expressed as the probability that a
+      particular threat will exploit a particular vulnerability with a
+      particular harmful result.
+
+
+
+
+
+
+Shirey                       Informational                    [Page 143]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (O) SET usage: "The possibility of loss because of one or more
+      threats to information (not to be confused with financial or
+      business risk)." [SET2]
+
+   $ risk analysis
+   $ risk assessment
+      (I) A process that systematically identifies valuable system
+      resources and threats to those resources, quantifies loss
+      exposures (i.e., loss potential) based on estimated frequencies
+      and costs of occurrence, and (optionally) recommends how to
+      allocate resources to countermeasures so as to minimize total
+      exposure.
+
+      (C) The analysis lists risks in order of cost and criticality,
+      thereby determining where countermeasures should be applied first.
+      It is usually financially and technically infeasible to counteract
+      all aspects of risk, and so some residual risk will remain, even
+      after all available countermeasures have been deployed. [FP031,
+      R2196]
+
+   $ risk management
+      (I) The process of identifying, controlling, and eliminating or
+      minimizing uncertain events that may affect system resources.
+      (See: risk analysis.)
+
+   $ Rivest Cipher #2 (RC2)
+      (N) A proprietary, variable-key-length block cipher invented by
+      Ron Rivest for RSA Data Security, Inc. (now a wholly-owned
+      subsidiary of Security Dynamics, Inc.).
+
+   $ Rivest Cipher #4 (RC4)
+      (N) A proprietary, variable-key-length stream cipher invented by
+      Ron Rivest for RSA Data Security, Inc. (now a wholly-owned
+      subsidiary of Security Dynamics, Inc.).
+
+   $ Rivest-Shamir-Adleman (RSA)
+      (N) An algorithm for asymmetric cryptography, invented in 1977 by
+      Ron Rivest, Adi Shamir, and Leonard Adleman [RSA78, Schn].
+
+      (C) 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.
+
+      (C) 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
+
+
+
+Shirey                       Informational                    [Page 144]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      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).
+
+      (C) 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 destroyed after computing n.)
+
+      (C) 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) = m to recover m.
+
+      (C) 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 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.
+
+      (C) 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 (as explained for 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.
+
+   $ role-based access control (RBAC)
+      (I) A form of identity-based access control where the system
+      entities that are identified and controlled are functional
+      positions in an organization or process.
+
+   $ root
+      (I) A CA that is directly trusted by an end entity. Acquiring the
+      value of a root CA's public key involves an out-of-band procedure.
+
+      (I) Hierarchical PKI usage: 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 trust. (See: top
+      CA.)
+
+
+
+
+
+Shirey                       Informational                    [Page 145]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (C) In a hierarchical PKI, a root 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. 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 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.
+
+      (O) MISSI usage: 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.
+
+      (O) UNIX usage: A user account (also called "superuser") that has
+      all privileges (including all security-related privileges) and
+      thus can manage the system and its other user accounts.
+
+   $ root certificate
+      (I) A certificate for which the subject is a root.
+
+      (I) Hierarchical PKI usage: The self-signed public-key certificate
+      at the top of a certification hierarchy.
+
+   $ root key
+      (I) A public key for which the matching private key is held by a
+      root.
+
+   $ root registry
+      (O) MISSI usage: A name previously used for a MISSI policy
+      approving authority.
+
+   $ router
+      (I) A computer that is a gateway between two networks at OSI layer
+      3 and that relays and directs data packets through that
+      internetwork. The most common form of router operates on IP
+      packets. (See: bridge.)
+
+      (I) Internet usage: In the context of the Internet protocol suite,
+      a networked computer that forwards Internet Protocol packets that
+      are not addressed to the computer itself. (See: host.)
+
+
+
+
+Shirey                       Informational                    [Page 146]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ RSA
+      See: Rivest-Shamir-Adleman.
+
+   $ rule-based security policy
+      (I) "A security policy based on global 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 Part 2] (See: identity-based security
+      policy.)
+
+   $ safety
+      (I) The property of a system being free from risk of causing harm
+      to system entities and outside entities.
+
+   $ SAID
+      See: security association identifier.
+
+   $ salt
+      (I) A random value that is concatenated with a password before
+      applying the one-way encryption function used to protect passwords
+      that are stored in the database of an access control system. (See:
+      initialization value.)
+
+      (C) Salt protects a password-based access control system against a
+      dictionary attack.
+
+   $ sanitize
+      (I) Delete sensitive data from a file, a device, or a system; or
+      modify data so as to be able to downgrade its classification
+      level.
+
+   $ SASL
+      See: Simple Authentication and Security Layer.
+
+   $ SCA
+      See: subordinate certification authority.
+
+   $ scavenging
+      See: (secondary definition under) threat consequence.
+
+   $ screening router
+      (I) A synonym for "filtering router".
+
+   $ SDE
+      See: Secure Data Exchange.
+
+
+
+
+
+Shirey                       Informational                    [Page 147]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ SDNS
+      See: Secure Data Network System.
+
+   $ seal
+      (O) To use cryptography to provide data integrity service for a
+      data object. (See: sign, wrap.)
+
+      (D) ISDs SHOULD NOT use this definition; instead, use language
+      that is more specific with regard to the mechanism(s) used, such
+      as "sign" when the mechanism is digital signature.
+
+   $ secret
+      (I) (1.) Adjective: The condition of information being protected
+      from being known by any system entities except those who are
+      intended to know it. (2.) Noun: An item of information that is
+      protected thusly.
+
+      (C) This term applies to symmetric keys, private keys, and
+      passwords.
+
+   $ secret-key cryptography
+      (I) A synonym for "symmetric cryptography".
+
+   $ Secure Data Exchange (SDE)
+      (N) A local area network security protocol defined by the IEEE
+      802.10 standard.
+
+   $ Secure Data Network System (SDNS)
+      (N) An NSA program that developed security protocols for
+      electronic mail (Message Security Protocol), OSI layer 3 (SP3),
+      OSI layer 4 (SP4), and key management (KMP).
+
+   $ Secure Hash Standard (SHS)
+      (N) The U.S. Government standard [FP180] that specifies the Secure
+      Hash Algorithm (SHA-1), a cryptographic hash function that
+      produces a 160-bit output (hash result) for input data of any
+      length < 2**64 bits.
+
+   $ Secure Hypertext Transfer Protocol (Secure-HTTP, S-HTTP)
+      (I) A Internet protocol for providing client-server security
+      services for HTTP communications. (See: https.)
+
+      (C) 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
+
+
+
+Shirey                       Informational                    [Page 148]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      parties for each transaction. S-HTTP supports both asymmetric and
+      symmetric key operation modes. 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 [R2633] to provide encryption and digital signatures for
+      Internet mail messages.
+
+   $ 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.)
+
+      (C) SSL is layered below HTTP and above a reliable transport
+      protocol (TCP). SSL is independent of the application it
+      encapsulates, and any higher level protocol can layer on top of
+      SSL transparently. However, many Internet applications might be
+      better served by IPsec.
+
+      (C) SSL has two layers: (a) SSL's lower layer, the SSL Record
+      Protocol, is layered on top of the transport protocol and
+      encapsulates higher level protocols. One such encapsulated
+      protocol is SSL Handshake Protocol. (b) SSL's upper layer provides
+      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 enables them to negotiate a symmetric encryption
+      algorithm and secret session key (to use for data confidentiality)
+      before the application protocol transmits or receives data. A
+      keyed hash provides data integrity service for encapsulated data.
+
+   $ secure state
+      (I) A system condition in which no subject can access any object
+      in an unauthorized manner. (See: (secondary definition under)
+      Bell-LaPadula Model, clean system.)
+
+   $ security
+      (I) (1.) Measures taken to protect a system. (2.) The condition of
+      a system that results from the establishment and maintenance of
+
+
+
+
+
+Shirey                       Informational                    [Page 149]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      measures to protect the system. (3.) The condition of system
+      resources being free from unauthorized access and from
+      unauthorized or accidental change, destruction, or loss.
+
+   $ 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 elements required to implement the
+      services, and (c) the performance levels required in the elements
+      to deal with the threat environment. (See: (discussion under)
+      security policy.)
+
+      (C) 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 (e.g., see: [R2179]). A complete security architecture
+      needs to deal with both intentional, intelligent threats and
+      accidental kinds of threats.
+
+   $ security association
+      (I) A relationship established between two or more entities to
+      enable them to protect data they exchange. The relationship is
+      used to negotiate characteristics of protection mechanisms, but
+      does not include the mechanisms themselves. (See: association.)
+
+      (C) A security association describes how entities will use
+      security services. The relationship is represented by a set of
+      information that is shared between the entities and is agreed upon
+      and considered a contract between them.
+
+      (O) IPsec usage: 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 selected, 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.
+
+   $ 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 protocol data
+      unit is bound. The SAID value is usually used to select a key for
+      decryption or authentication at the destination. (See: Security
+      Parameter Index.)
+
+
+
+
+Shirey                       Informational                    [Page 150]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ 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 Part 2, NCS01]
+
+      (C) 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 attacks and security compromises.
+
+   $ 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 class
+      (D) A synonym for "security level". For consistency, ISDs SHOULD
+      use "security level" instead of "security class".
+
+   $ 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. (See: data
+      compromise, violation.)
+
+   $ security domain
+      See: domain.
+
+   $ security environment
+      (I) The set of external entities, procedures, and conditions that
+      affect secure development, operation, and maintenance of a system.
+
+   $ security event
+      (I) A occurrence in a system that is relevant to the security of
+      the system. (See: security incident.)
+
+
+
+
+
+
+Shirey                       Informational                    [Page 151]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (C) The term includes 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:
+
+       - 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 information to an X.500 Directory.
+       - Receiving a key compromise notification.
+       - Receiving an improper certification request.
+       - Detecting an alarm condition reported by a cryptographic
+         module.
+       - Logging the operator in or out.
+       - 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 a logic
+      gate level, gate-by-gate, to determine the security properties of
+      a device when a hardware fault is encountered.
+
+   $ security gateway
+      (I) A gateway that separates trusted (or relatively more trusted)
+      hosts on the internal network side from untrusted (or less
+      trusted) hosts on the external network side. (See: firewall and
+      guard.)
+
+      (O) IPsec usage: "An intermediate system that implements IPsec
+      protocols." [R2401] Normally, AH or ESP is implemented to serve a
+      set of internal hosts, providing security services for the hosts
+      when they communicate with other, external hosts or gateways that
+      also implement IPsec.
+
+   $ security incident
+      (I) A security event that involves a security violation. (See:
+      CERT, GRIP, security event, security intrusion, security
+      violation.)
+
+      (C) In other words, a security-relevant system event in which the
+      system's security policy is disobeyed or otherwise breached.
+
+      (O) "Any adverse event which compromises some aspect of computer
+      or network security." [R2350]
+
+
+
+
+
+Shirey                       Informational                    [Page 152]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (D) ISDs SHOULD NOT use this "O" definition because (a) a security
+      incident may occur without actually being harmful (i.e., adverse)
+      and (b) this Glossary defines "compromise" more narrowly in
+      relation to unauthorized access.
+
+   $ 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.
+
+   $ 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: reference monitor.)
+
+      (C) That is, a security kernel is an implementation of a reference
+      monitor for a given hardware base.
+
+   $ security label
+      (I) A marking that is bound to a system resource and that names or
+      designates the security-relevant attributes of that resource.
+      [I7498 Part 2, R1457]
+
+      (C) The recommended definition is usefully broad, but usually the
+      term is understood more narrowly as a marking that represents the
+      security level of an information object, i.e., a marking that
+      indicates how sensitive an information object is. [NCS04]
+
+      (C) System security mechanisms interpret security labels according
+      to applicable security policy to determine how to control access
+      to the associated information, otherwise constrain its handling,
+      and affix appropriate security markings to visible (printed and
+      displayed) images thereof. [FP188]
+
+   $ security level
+      (I) The combination of a hierarchical classification level and a
+      set of non-hierarchical category designations that represents how
+      sensitive information is. (See: (usage note under) classification
+      level, dominate, lattice model.)
+
+   $ security management infrastructure (SMI)
+      (I) System elements and activities that support security policy by
+      monitoring and controlling security services and mechanisms,
+      distributing security information, and reporting security events.
+      The associated functions are as follows [I7498-4]:
+
+
+
+
+Shirey                       Informational                    [Page 153]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+       - 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: public-key infrastructure.)
+
+   $ security mechanism
+      (I) A process (or a device incorporating such a process) that can
+      be used in a system to implement a security service that is
+      provided by or within the system. (See: (discussion under)
+      security policy.)
+
+      (C) Some examples of security mechanisms are 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. (See: (discussion under) security policy.)
+
+      (C) An example is the Bell-LaPadula Model.
+
+   $ security parameters index (SPI)
+      (I) IPsec usage: The type of security association identifier used
+      in IPsec protocols. A 32-bit value used to distinguish among
+      different security associations terminating at the same
+      destination (IP address) and using the same IPsec 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.
+
+   $ security perimeter
+      (I) The boundary of the domain in which a security policy or
+      security architecture applies; i.e., the boundary of the space in
+      which security services protect system resources.
+
+
+
+
+
+
+Shirey                       Informational                    [Page 154]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ security policy
+      (I) A set of rules and practices that specify or regulate how a
+      system or organization provides security services to protect
+      sensitive and critical system resources. (See: identity-based
+      security policy, rule-based security policy, security
+      architecture, security mechanism, security model.)
+
+      (O) "The set of rules laid down by the security authority
+      governing the use and provision of security services and
+      facilities." [X509]
+
+      (C) Ravi Sandhu notes 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?
+          ^
+          | + - - - - - - - - - - - +
+          | | Security Policy       |
+          | + - - - - - - - - - - - +    + - - - - - - - - - - - - - - +
+          | | Security Model        |    | A "top-level specification" |
+          | + - - - - - - - - - - - + <- | is at a level below "model" |
+          | | Security Architecture |    | but above "architecture".   |
+          | + - - - - - - - - - - - +    + - - - - - - - - - - - - - - +
+          | | Security Mechanism    |
+          | + - - - - - - - - - - - +
+          v
+         How Are Security Services Implemented?
+
+   $ Security Protocol 3 (SP3)
+      (O) A protocol [SDNS3] developed by SDNS to provide connectionless
+      data security at the top of OSI layer 3. (See: 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 OSI layer 4. (See: TLSP.)
+
+   $ security-relevant event
+      See: security event.
+
+   $ security service
+      (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,
+
+
+
+
+Shirey                       Informational                    [Page 155]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      data confidentiality service, data integrity service, data origin
+      authentication service, non-repudiation service, peer entity
+      authentication service, system integrity service.)
+
+      (O) "A service, provided by a layer of communicating open systems,
+      which ensures adequate security of the systems or the data
+      transfers." [I7498 Part 2]
+
+      (C) Security services implement security policies, and are
+      implemented by security mechanisms.
+
+   $ security situation
+      (I) ISAKMP usage: The set of all security-relevant information--
+      e.g., network addresses, security classifications, manner of
+      operation (normal or emergency)--that is needed to decide the
+      security services that are required to protect the association
+      that is being negotiated.
+
+   $ security token
+      See: token.
+
+   $ security violation
+      (I) An act or event that disobeys or otherwise breaches security
+      policy. (See: compromise, penetration, security incident.)
+
+   $ 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.
+      (See: root certificate.)
+
+      (C) In a self-signed X.509 public-key certificate, the issuer's DN
+      is the same as the subject's DN.
+
+   $ semantic security
+      (I) An attribute of a encryption algorithm that is a formalization
+      of the notion that the algorithm not only hides the plaintext but
+      also reveals no partial information about the plaintext. Whatever
+      is efficiently computable about the plaintext when given the
+      ciphertext, is also efficiently computable without the ciphertext.
+      (See: indistinguishability.)
+
+   $ sensitive (information)
+      (I) Information is sensitive if disclosure, alteration,
+      destruction, or loss of the information would adversely affect the
+      interests or business of its owner or user. (See: critical.)
+
+
+
+
+
+Shirey                       Informational                    [Page 156]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ separation of duties
+      (I) The practice of dividing the steps in a system function among
+      different individuals, so as to keep a single individual from
+      subverting the process. (See: dual control, administrative
+      security.)
+
+   $ serial number
+      See: certificate serial number.
+
+   $ server
+      (I) A system entity that provides a service in response to
+      requests from other system entities called clients.
+
+   $ 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 key, key distribution center, master key.)
+
+      (C) Usually, a session key is used for a defined period of
+      communication between two computers, 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
+      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.
+
+      (C) In addition to 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
+      qualifiers:
+
+       - A URL where a copy of the policy statement may be found.
+       - An electronic mail address where a copy of the policy statement
+         may be found.
+
+
+
+Shirey                       Informational                    [Page 157]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+       - A hash result of the policy statement, computed using the
+         indicated algorithm.
+       - 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, issuer, merchant, payment gateway, third party.)
+
+      (C) This term and acronym are trademarks of SETCo. MasterCard and
+      Visa announced the SET standard on 1 February 1996. On 19 December
+      1997, MasterCard and Visa formed SET Secure Electronic Transaction
+      LLC (commonly referred to as "SETCo") to implement the SET 1.0
+      specification. A memorandum of understanding adds American Express
+      and JCB Credit Card Company as co-owners of SETCo.
+
+   $ SETCo
+      See: (secondary definition under) SET Secure Electronic
+      Transaction.
+
+   $ SHA-1
+      See: Secure Hash Standard.
+
+   $ shared secret
+      (I) A synonym for "keying material" or "cryptographic key".
+
+   $ S-HTTP
+      See: Secure HTTP.
+
+   $ sign
+      (I) Create a digital signature for a data object.
+
+   $ signature
+      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.
+
+      (C) A v3 X.509 public-key certificate may have a "keyUsage"
+      extension which indicates the purpose for which the certified
+      public key is intended.
+
+
+
+Shirey                       Informational                    [Page 158]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ signer
+      (N) A human being or an organization entity that uses its private
+      key to create a digital signature for a data object. [ABA]
+
+   $ SILS
+      See: Standards for Interoperable LAN/MAN Security.
+
+   $ simple authentication
+      (I) An authentication process that uses a password as the
+      information needed to verify an identity claimed for an entity.
+      (See: strong authentication.)
+
+      (O) "Authentication by means of simple password arrangements."
+      [X509]
+
+   $ Simple Authentication and Security Layer (SASL)
+      (I) An Internet specification [R2222] for adding authentication
+      service to connection-based protocols. 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, GSSAPI, 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.
+      [R2356] (See: IKE, IPsec.)
+
+      (C) SKIP uses the Diffie-Hellman 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 of the entities to the other. The KEK is used with a
+      symmetric algorithm 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
+      [R0821] for moving electronic mail messages from one computer to
+      another.
+
+   $ Simple Network Management Protocol (SNMP)
+      (I) A UDP-based, application-layer, Internet Standard protocol
+      [R2570, R2574] for conveying management information between
+      managers and agents.
+
+
+
+
+Shirey                       Informational                    [Page 159]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (C) SNMP version 1 uses cleartext passwords for authentication and
+      access control. (See: community string.) Version 2 adds
+      cryptographic mechanisms based on DES and MD5. Version 3 provides
+      enhanced, integrated support for security services, including data
+      confidentiality, data integrity, data origin authentication, and
+      message timeliness and limited replay protection.
+
+   $ simple security property
+      See: (secondary definition under) Bell-LaPadula Model.
+
+   $ single sign-on
+      (I) A system that enables a user to access multiple computer
+      platforms (usually a set of hosts on the same network) or
+      application systems after being authenticated just one time. (See:
+      Kerberos.)
+
+      (C) Typically, a user logs in just once, and then is transparently
+      granted access to a variety of permitted resources with no further
+      login being required until after the user logs out. Such a system
+      has the advantages of being user friendly and enabling
+      authentication to be managed consistently across an entire
+      enterprise, and has the disadvantage of requiring all hosts and
+      applications to trust the same authentication mechanism.
+
+   $ situation
+      See: security situation.
+
+   $ 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]
+
+      (C) 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.
+
+   $ SKIP
+      See: Simple Key-management for IP.
+
+
+
+
+
+
+
+Shirey                       Informational                    [Page 160]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ SKIPJACK
+      (N) A Type II block cipher [NIST] with a block size of 64 bits and
+      a key size of 80 bits, that was developed by NSA and formerly
+      classified at the U.S. Department of Defense "Secret" level. (See:
+      CAPSTONE, CLIPPER, FORTEZZA, Key Exchange Algorithm.)
+
+      (C) On 23 June 1998, NSA announced that SKIPJACK had been
+      declassified.
+
+   $ slot
+      (O) MISSI usage: One of the FORTEZZA PC card storage areas that
+      are each able to hold an X.509 certificate and additional data
+      that is associated with the certificate, such as the matching
+      private key.
+
+   $ smart card
+      (I) A credit-card sized device containing one or more integrated
+      circuit chips, which perform the functions of a computer's central
+      processor, memory, and input/output interface. (See: PC card.)
+
+      (C) 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.
+
+      (C) A "smart token" is a device that conforms to the definition of
+      smart card except that rather than having standard credit card
+      dimensions, the token is packaged in some other form, such as a
+      dog tag or door key shape.
+
+   $ smart token
+      See: (secondary definition under) smart card.
+
+   $ SMI
+      See: security management infrastructure.
+
+   $ S/MIME
+      See: Secure/MIME.
+
+   $ SMTP
+      See: Simple Mail Transfer Protocol.
+
+   $ smurf
+      (I) Software that mounts a denial-of-service attack ("smurfing")
+      by exploiting IP broadcast addressing and ICMP ping packets to
+      cause flooding. (See: flood, ICMP flood.)
+
+
+
+Shirey                       Informational                    [Page 161]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (D) ISDs SHOULD NOT use this term because it is not listed in most
+      dictionaries and could confuse international readers.
+
+      (C) A smurf program builds a network packet that appears to
+      originate from another address, that of the "victim", either a
+      host or an IP router. The packet contains an ICMP ping message
+      that is addressed to an IP broadcast address, i.e., to all IP
+      addresses in a given network. The echo responses to the ping
+      message return to the victim's address. The goal of smurfing may
+      be either to deny service at a particular host or to flood all or
+      part of an IP network.
+
+   $ sniffing
+      (C) A synonym for "passive wiretapping". (See: password sniffing.)
+
+      (D) ISDs SHOULD NOT use this term because it unnecessarily
+      duplicates the meaning of a term that is better established. (See:
+      (usage note under) Green Book.
+
+   $ SNMP
+      See: Simple Network Management Protocol.
+
+   $ social engineering
+      (I) A euphemism for non-technical or low-technology means--such as
+      lies, impersonation, tricks, bribes, blackmail, and threats--used
+      to attack information systems. (See: masquerade attack.)
+
+      (D) ISDs SHOULD NOT use this term because it is vague; instead,
+      use a term that is specific with regard to the means of attack.
+
+   $ SOCKS
+      (I) An Internet protocol [R1928] that provides a generalized proxy
+      server that enables client-server applications--such as TELNET,
+      FTP, and HTTP; running over either TCP or UDP--to use the services
+      of a firewall.
+
+      (C) SOCKS is layered under the 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.
+
+
+
+
+
+
+Shirey                       Informational                    [Page 162]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ soft TEMPEST
+      (O) The use of software techniques to reduce the radio frequency
+      information leakage from computer displays and keyboards. [Kuhn]
+      (See: TEMPEST.)
+
+   $ 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. (See: firmware, hardware.)
+
+   $ SORA
+      See: SSO-PIN ORA.
+
+   $ source authentication
+      (D) ISDs SHOULD NOT use this term because it is ambiguous. If the
+      intent is to authenticate the original creator or packager of data
+      received, then say "data origin authentication". If the intent is
+      to authenticate the identity of the sender of data, then say "peer
+      entity authentication". (See: data origin authentication, peer
+      entity authentication).
+
+   $ source integrity
+      (I) The degree of confidence that can be placed in information
+      based on the trustworthiness of its sources. (See: integrity.)
+
+   $ SP3
+      See: Security Protocol 3.
+
+   $ SP4
+      See: Security Protocol 4.
+
+   $ spam
+      (I) (1.) Verb: To indiscriminately send unsolicited, unwanted,
+      irrelevant, or inappropriate messages, especially commercial
+      advertising in mass quantities. (2.) Noun: electronic "junk mail".
+      [R2635]
+
+      (D) This term SHOULD NOT be written in upper-case 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 commercial email (UCE)], 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."
+
+
+
+
+
+Shirey                       Informational                    [Page 163]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (C) In sufficient volume, spam can cause denial of service. (See:
+      flooding.) According to the SPAM Web site, the term was adopted as
+      a result of the Monty Python skit in which a group of Vikings sang
+      a chorus of 'SPAM, SPAM, SPAM . . .' in an increasing crescendo,
+      drowning out other conversation. Hence, the analogy applied
+      because UCE was drowning out normal discourse on the Internet.
+
+   $ SPC
+      See: software publisher certificate.
+
+   $ SPI
+      See: Security Parameters Index.
+
+   $ split key
+      (I) A cryptographic key that is divided into 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
+      (I) A security technique in which two or more entities separately
+      hold data items that individually convey no knowledge of the
+      information that results from combining the items. (See: dual
+      control, split key.)
+
+      (O) "A condition under which two or more entities separately have
+      key components which individually convey no knowledge of the
+      plaintext key which will be produced when the key components are
+      combined in the cryptographic module." [FP140]
+
+   $ spoofing attack
+      (I) A synonym for "masquerade attack".
+
+   $ SSH
+      (I) A protocol for secure remote login and other secure network
+      services over an insecure network.
+
+      (C) Consists of three major components:
+
+       - Transport layer protocol: Provides server authentication,
+         confidentiality, and integrity. It may optionally also provide
+         compression. The transport layer will typically be run over a
+         TCP/IP connection, but might also be used 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.
+
+
+
+
+Shirey                       Informational                    [Page 164]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+       - Connection protocol: Multiplexes the encrypted tunnel into
+         several logical channels. It runs over the user authentication
+         protocol.
+
+   $ SSL
+      See: Secure Sockets Layer, Standard Security Label.
+
+   $ SSO
+      See: system security officer.
+
+   $ SSO PIN
+      (O) MISSI usage: One of two personal identification numbers that
+      control access to the functions and stored data of a FORTEZZA PC
+      card. Knowledge of the SSO PIN enables the card user to perform
+      the FORTEZZA functions intended for use by an end user and also
+      the functions intended for use by a MISSI certification authority.
+      (See: user PIN.)
+
+   $ SSO-PIN ORA (SORA)
+      (O) MISSI usage: 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 an end user's
+      FORTEZZA PC card.
+
+   $ Standards for Interoperable LAN/MAN Security (SILS)
+      (N) (1.) The IEEE 802.10 standards committee. (2.) A developing
+      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
+      (I) (Written "*-property".) See: "confinement property" under
+      Bell-LaPadula Model.
+
+   $ Star Trek attack
+      (C) An attack that penetrates your system where no attack has ever
+      gone before.
+
+   $ 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. (See: cryptology.)
+
+      (C) An example of a steganographic method is "invisible" ink.
+      (See: digital watermark.)
+
+
+
+Shirey                       Informational                    [Page 165]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ storage channel
+      See: (secondary definition under) covert channel.
+
+   $ stream cipher
+      (I) An encryption algorithm that breaks plaintext into a stream of
+      successive bits (or characters) and encrypts the n-th plaintext
+      bit with the n-th element of a parallel key stream, thus
+      converting the plaintext bit stream into a ciphertext bit stream.
+      [Schn] (See: block cipher.)
+
+   $ strong authentication
+      (I) An authentication process that uses cryptography--particularly
+      public-key certificates--to verify the identity claimed for an
+      entity. (See: X.509.)
+
+      (O) "Authentication by means of cryptographically derived
+      credentials." [X509]
+
+   $ subject
+      1. (I) In a computer system: A system entity that causes
+      information to flow among objects or changes the system state;
+      technically, a process-domain pair. (See: Bell-LaPadula Model.)
+
+      2. (I) Of a certificate: The entity name that is bound to the data
+      items in a digital certificate, and particularly a name that is
+      bound to a key value in a public-key certificate.
+
+   $ subnetwork
+      (N) An OSI term for a system of packet relays and connecting links
+      that implement the lower three protocol layers of the OSIRM to
+      provide a communication service that interconnects attached end
+      systems. Usually the relays operate at OSI layer 3 and are all of
+      the same type (e.g., all X.25 packet switches, or all interface
+      units in an IEEE 802.3 LAN). (See: gateway, internet, router.)
+
+   $ subordinate certification authority (SCA)
+      (I) A CA whose public-key certificate is issued by another
+      (superior) CA. (See: certification hierarchy.)
+
+      (O) MISSI usage: The fourth-highest (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
+
+
+
+
+
+Shirey                       Informational                    [Page 166]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      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 distinguished name
+      (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>.
+
+   $ superencryption
+      (I) An encryption operation for which the plaintext input to be
+      transformed is the ciphertext output of a previous encryption
+      operation.
+
+   $ survivability
+      (I) The ability of a system to remain in operation or existence
+      despite adverse conditions, including both natural occurrences,
+      accidental actions, and attacks on the system. (See: availability,
+      reliability.)
+
+   $ symmetric cryptography
+      (I) A branch of cryptography involving algorithms that use the
+      same key for two different steps of the algorithm (such as
+      encryption and decryption, or signature creation and signature
+      verification). (See: asymmetric cryptography.)
+
+      (C) Symmetric cryptography has been used for thousands of years
+      [Kahn]. A modern example of a symmetric encryption algorithm is
+      the U.S. Government's Data Encryption Algorithm. (See: DEA, DES.)
+
+      (C) Symmetric cryptography is sometimes called "secret-key
+      cryptography" (versus public-key cryptography) because the
+      entities that share the key, such as the originator and the
+      recipient of a message, need to keep the key secret. For example,
+      when Alice wants to ensure confidentiality for data she sends to
+      Bob, she encrypts the data with a secret key, and Bob uses the
+      same key to decrypt. Keeping the shared key secret entails both
+      cost and risk when the key is distributed to both Alice and Bob.
+      Thus, symmetric cryptography has a key management disadvantage
+      compared to asymmetric cryptography.
+
+   $ symmetric key
+      (I) A cryptographic key that is used in a symmetric cryptographic
+      algorithm.
+
+
+
+
+Shirey                       Informational                    [Page 167]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ SYN flood
+      (I) A denial of service attack that sends a host more TCP SYN
+      packets (request to synchronize sequence numbers, used when
+      opening a connection) than the protocol implementation can handle.
+      (See: flooding.)
+
+   $ system
+      (C) In this Glossary, the term is mainly used as an abbreviation
+      for "automated information system".
+
+   $ system entity
+      (I) An active element of a system--e.g., an automated process, a
+      subsystem, a person or group of persons--that incorporates a
+      specific set of capabilities.
+
+   $ system high
+      (I) The highest security level supported by a system at a
+      particular time or in a particular environment. (See: system high
+      security mode.)
+
+   $ system high security mode
+      (I) A mode of operation of an information system, wherein all
+      users having access to the system possess a security clearance or
+      authorization, but not necessarily a need-to-know, for all data
+      handled by the system. (See: mode of operation.)
+
+      (C) This mode is defined formally in U.S. Department of Defense
+      policy regarding system accreditation [DOD2], but the term is
+      widely used outside the Defense Department and outside the
+      Government.
+
+   $ system integrity
+      (I) "The quality that a system has when it can perform its
+      intended function in a unimpaired manner, free from deliberate or
+      inadvertent unauthorized manipulation." [NCS04] (See: system
+      integrity service.)
+
+   $ 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. (See: system
+      high.)
+
+
+
+
+
+Shirey                       Informational                    [Page 168]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ system resource
+      (I) Data contained in an information system; or a service provided
+      by a system; or a system capability, such as processing power or
+      communication bandwidth; or an item of system equipment (i.e., a
+      system component--hardware, firmware, software, or documentation);
+      or a facility that houses system operations and equipment.
+
+   $ system security officer (SSO)
+      (I) A person responsible for enforcement or administration of the
+      security policy that applies to the system.
+
+   $ system verification
+      See: (secondary definition under) verification.
+
+   $ TACACS
+   $ TACACS+
+      See: Terminal Access Controller (TAC) Access Control System.
+
+   $ 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.
+
+   $ TCB
+      See: trusted computing base.
+
+   $ TCP
+      See: Transmission Control Protocol.
+
+   $ TCP/IP
+      (I) A synonym for "Internet Protocol Suite", in which the
+      Transmission Control Protocol (TCP) and the Internet Protocol (IP)
+      are important parts.
+
+   $ TCSEC
+      See: Trusted Computer System Evaluation Criteria.
+
+   $ TELNET
+      (I) A TCP-based, application-layer, Internet Standard protocol
+      [R0854] for remote login from one host to another.
+
+   $ TEMPEST
+      (O) A nickname for specifications and standards for limiting the
+      strength of electromagnetic emanations from electrical and
+      electronic equipment and thus reducing vulnerability to
+      eavesdropping. This term originated in the U.S. Department of
+      Defense. [Army, Kuhn, Russ] (See: emanation security, soft
+      tempest.)
+
+
+
+Shirey                       Informational                    [Page 169]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (D) ISDs SHOULD NOT use this term as a synonym for
+      "electromagnetic emanations security".
+
+   $ 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.
+
+      (C) TACACS was developed for ARPANET and has evolved for use in
+      commercial equipment. TACs were a type of network access server
+      computer used to connect terminals to the early Internet, usually
+      using dial-up modem connections. TACACS used centralized
+      authentication servers and served not only network access servers
+      like TACs but also routers and other networked computing devices.
+      TACs are no longer in use, but TACACS+ is. [R1983]
+
+       - "XTACACS": The name of Cisco Corporation's implementation,
+         which enhances and extends the original TACACS.
+
+       - "TACACS+": A TCP-based protocol that improves on TACACS and
+         XTACACS by separating the functions of authentication,
+         authorization, and accounting and by encrypting all traffic
+         between the network access server and authentication server. It
+         is extensible to allow any authentication mechanism to be used
+         with TACACS+ clients.
+
+   $ TESS
+      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 employs asymmetric cryptography,
+      based on discrete exponentiation, and a structure of self-
+      certified public keys. [R1824]
+
+   $ threat
+      (I) A potential for violation of security, which exists when there
+      is a circumstance, capability, action, or event that could breach
+      security and cause harm. (See: attack, threat action, threat
+      consequence.)
+
+      (C) That is, a threat is a possible danger that might exploit a
+      vulnerability. A threat can be either "intentional" (i.e.,
+      intelligent; e.g., an individual cracker or a criminal
+
+
+
+
+Shirey                       Informational                    [Page 170]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      organization) or "accidental" (e.g., the possibility of a computer
+      malfunctioning, or the possibility of an "act of God" such as an
+      earthquake, a fire, or a tornado).
+
+      (C) In some contexts, such as the following, the term is used
+      narrowly to refer only to intelligent threats:
+
+      (N) U. S. Government usage: The technical and operational
+      capability of a hostile entity to detect, exploit, or subvert
+      friendly information systems and the demonstrated, presumed, or
+      inferred intent of that entity to conduct such activity.
+
+   $ threat action
+      (I) An assault on system security. (See: attack, threat, threat
+      consequence.)
+
+      (C) A complete security architecture deals with both intentional
+      acts (i.e. attacks) and accidental events [FIPS31]. Various kinds
+      of threat actions are defined as subentries under "threat
+      consequence".
+
+   $ threat analysis
+      (I) An analysis of the probability of occurrences and consequences
+      of damaging actions to a system.
+
+   $ threat consequence
+      (I) A security violation that results from a threat action.
+      Includes disclosure, deception, disruption, and usurpation. (See:
+      attack, threat, threat action.)
+
+      (C) The following subentries describe four kinds of threat
+      consequences, and also list and describe the kinds of threat
+      actions that cause each consequence. Threat actions that are
+      accidental events are marked by "*".
+
+      1. "(Unauthorized) Disclosure" (a threat consequence): A
+         circumstance or event whereby an entity gains access to data
+         for which the entity is not authorized. (See: data
+         confidentiality.) The following threat actions can cause
+         unauthorized disclosure:
+
+         A. "Exposure": A threat action whereby sensitive data is
+            directly released to an unauthorized entity. This includes:
+
+            a. "Deliberate Exposure": Intentional release of sensitive
+               data to an unauthorized entity.
+
+
+
+
+
+Shirey                       Informational                    [Page 171]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+            b. "Scavenging": Searching through data residue in a system
+               to gain unauthorized knowledge of sensitive data.
+
+            c* "Human error": Human action or inaction that
+               unintentionally results in an entity gaining unauthorized
+               knowledge of sensitive data.
+
+            d* "Hardware/software error". System failure that results in
+               an entity gaining unauthorized knowledge of sensitive
+               data.
+
+         B. "Interception": A threat action whereby an unauthorized
+            entity directly accesses sensitive data traveling between
+            authorized sources and destinations. This includes:
+
+            a. "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.
+
+            b. "Wiretapping (passive)": Monitoring and recording data
+               that is flowing between two points in a communication
+               system. (See: wiretapping.)
+
+            c. "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 is not intended to communicate the data. (See:
+               emanation.)
+
+         C. "Inference": A threat action whereby an unauthorized entity
+            indirectly accesses sensitive data (but not necessarily the
+            data contained in the communication) by reasoning from
+            characteristics or byproducts of communications. This
+            includes:
+
+            a. Traffic analysis: Gaining knowledge of data by observing
+               the characteristics of communications that carry the
+               data. (See: (main Glossary entry for) traffic analysis.)
+
+            b. "Signals analysis": Gaining indirect knowledge 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.)
+
+         D. "Intrusion": A threat action whereby an unauthorized entity
+            gains access to sensitive data by circumventing a system's
+            security protections. This includes:
+
+
+
+Shirey                       Informational                    [Page 172]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+            a. "Trespass": Gaining unauthorized physical access to
+               sensitive data by circumventing a system's protections.
+
+            b. "Penetration": Gaining unauthorized logical access to
+               sensitive data by circumventing a system's protections.
+
+            c. "Reverse engineering": Acquiring sensitive data by
+               disassembling and analyzing the design of a system
+               component.
+
+            d. Cryptanalysis: Transforming encrypted data into plaintext
+               without having prior knowledge of encryption parameters
+               or processes. (See: (main Glossary entry for)
+               cryptanalysis.)
+
+      2. "Deception" (a threat consequence): A circumstance or event
+         that may result in an authorized entity receiving false data
+         and believing it to be true. The following threat actions can
+         cause deception:
+
+         A. "Masquerade": A threat action whereby an unauthorized entity
+            gains access to a system or performs a malicious act by
+            posing as an authorized entity. (See: (main Glossary entry
+            for) masquerade attack.)
+
+            a. "Spoof": Attempt by an unauthorized entity to gain access
+               to a system by posing as an authorized user.
+
+            b. "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:
+               (main Glossary entry for) malicious logic.)
+
+         B. "Falsification": A threat action whereby false data deceives
+            an authorized entity. (See: active wiretapping.)
+
+            a. "Substitution": Altering or replacing valid data with
+               false data that serves to deceive an authorized entity.
+
+            b. "Insertion": Introducing false data that serves to
+               deceive an authorized entity.
+
+         C. "Repudiation": A threat action whereby an entity deceives
+            another by falsely denying responsibility for an act. (See:
+            non-repudiation service, (main Glossary entry for)
+            repudiation.)
+
+
+
+Shirey                       Informational                    [Page 173]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+            a. "False denial of origin": Action whereby the originator
+               of data denies responsibility for its generation.
+
+            b. "False denial of receipt": Action whereby the recipient
+               of data denies receiving and possessing the data.
+
+      3. "Disruption" (a threat consequence): A circumstance or event
+         that interrupts or prevents the correct operation of system
+         services and functions. (See: denial of service.) The following
+         threat actions can cause disruption:
+
+         A. "Incapacitation": A threat action that prevents or
+            interrupts system operation by disabling a system component.
+
+            a. "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: (main Glossary entry for)
+               malicious logic.)
+
+            b. "Physical destruction": Deliberate destruction of a
+               system component to interrupt or prevent system
+               operation.
+
+            c* "Human error": Action or inaction that unintentionally
+               disables a system component.
+
+            d* "Hardware or software error": Error that causes failure
+               of a system component and leads to disruption of system
+               operation.
+
+            e* "Natural disaster": Any "act of God" (e.g., fire, flood,
+               earthquake, lightning, or wind) that disables a system
+               component. [FP031 section 2]
+
+         B. "Corruption": A threat action that undesirably alters system
+            operation by adversely modifying system functions or data.
+
+            a. "Tamper": In context of corruption, deliberate alteration
+               of a system's logic, data, or control information to
+               interrupt or prevent correct operation of system
+               functions.
+
+            b. "Malicious logic": In context of corruption, any
+               hardware, firmware, or software (e.g., a computer virus)
+               intentionally introduced into a system to modify system
+               functions or data. (See: (main Glossary entry for)
+               malicious logic.)
+
+
+
+Shirey                       Informational                    [Page 174]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+            c* "Human error": Human action or inaction that
+               unintentionally results in the alteration of system
+               functions or data.
+
+            d* "Hardware or software error": Error that results in the
+               alteration of system functions or data.
+
+            e* "Natural disaster": Any "act of God" (e.g., power surge
+               caused by lightning) that alters system functions or
+               data. [FP031 section 2]
+
+         C. "Obstruction": A threat action that interrupts delivery of
+            system services by hindering system operations.
+
+            a. "Interference": Disruption of system operations by
+               blocking communications or user data or control
+               information.
+
+            b. "Overload": Hindrance of system operation by placing
+               excess burden on the performance capabilities of a system
+               component. (See: flooding.)
+
+      4. "Usurpation" (a threat consequence): A circumstance or event
+         that results in control of system services or functions by an
+         unauthorized entity. The following threat actions can cause
+         usurpation:
+
+         A. "Misappropriation": A threat action whereby an entity
+            assumes unauthorized logical or physical control of a system
+            resource.
+
+            a. "Theft of service": Unauthorized use of service by an
+               entity.
+
+            b. "Theft of functionality": Unauthorized acquisition of
+               actual hardware, software, or firmware of a system
+               component.
+
+            c. "Theft of data": Unauthorized acquisition and use of
+               data.
+
+         B. "Misuse": A threat action that causes a system component to
+            perform a function or service that is detrimental to system
+            security.
+
+            a. "Tamper": In context of misuse, deliberate alteration of
+               a system's logic, data, or control information to cause
+               the system to perform unauthorized functions or services.
+
+
+
+Shirey                       Informational                    [Page 175]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+            b. "Malicious logic": In context of misuse, any hardware,
+               software, or firmware intentionally introduced into a
+               system to perform or control execution of an unauthorized
+               function or service.
+
+            c. "Violation of permissions": Action by an entity that
+               exceeds the entity's system privileges by executing an
+               unauthorized function.
+
+   $ thumbprint
+      (I) A pattern of curves formed by the ridges on the tip of a
+      thumb. (See: biometric authentication, fingerprint.)
+
+      (D) ISDs SHOULD NOT use this term as a synonym for "hash result"
+      because that meaning mixes concepts in a potentially misleading
+      way.
+
+   $ ticket
+      (I) A synonym for "capability". (See: Kerberos.)
+
+      (C) 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 have been implemented with
+      symmetric cryptography, but can also be implemented as attribute
+      certificates using asymmetric cryptography.
+
+   $ timing channel
+      See: (secondary definition under) covert channel.
+
+   $ TLS
+      See: Transport Layer Security. (See: TLSP.)
+
+   $ TLSP
+      See: Transport Layer Security Protocol. (See: TLS.)
+
+   $ token
+      1. (I) General usage: 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.
+
+      2. (I) Authentication usage: A data object or a portable, user-
+      controlled, physical device used to verify an identity in an
+      authentication process. (See: authentication information, dongle.)
+
+      3. (I) Cryptographic usage: See: cryptographic token.
+
+
+
+
+
+Shirey                       Informational                    [Page 176]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      4. (O) SET usage: "A portable device [e.g., smart card or PCMCIA
+      card] specifically designed to store cryptographic information and
+      possibly perform cryptographic functions in a secure manner."
+      [SET2]
+
+   $ 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 of initializing security tokens (e.g., see: smart
+      card), loading data into the tokens, and controlling the tokens
+      during their life cycle. 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.
+
+   $ 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.
+
+   $ token storage key
+      (I) A cryptography key used to protect data that is stored on a
+      security token.
+
+   $ top CA
+      (I) A CA that is the highest level (i.e., is the most trusted CA)
+      in a certification hierarchy. (See: root.)
+
+   $ 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: (discussion under)
+      security policy.)
+
+      (C) A top-level specification may be descriptive or formal:
+
+
+
+
+
+
+Shirey                       Informational                    [Page 177]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+       - "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.)
+
+   $ traffic analysis
+      (I) Inference of information from observable characteristics of
+      data flow(s), even when the data is encrypted or otherwise not
+      directly available. Such characteristics include the identities
+      and locations of the source(s) and destination(s), and the
+      presence, amount, frequency, and duration of occurrence. (See:
+      wiretapping.)
+
+      (O) "The inference of information from observation of traffic
+      flows (presence, absence, amount, direction, and frequency)."
+      [I7498 Part 2]
+
+   $ traffic flow confidentiality
+      (I) A data confidentiality service to protect against traffic
+      analysis.
+
+      (O) "A confidentiality service to protect against traffic
+      analysis." [I7498 Part 2]
+
+   $ traffic padding
+      (I) "The generation of spurious instances of communication,
+      spurious data units, and/or spurious data within data units."
+      [I7498 Part 2]
+
+   $ tranquillity property
+      See: (secondary definition under) Bell-LaPadula Model.
+
+   $ Transmission Control Protocol (TCP)
+      (I) An Internet Standard protocol [R0793] that reliably delivers a
+      sequence of datagrams (discrete sets of bits) from one computer to
+      another in a computer network. (See: TCP/IP.)
+
+      (C) TCP is designed to fit into a layered hierarchy of protocols
+      that support internetwork applications. TCP assumes it can obtain
+      a simple, potentially unreliable datagram service (such as the
+      Internet Protocol) from the lower-layer protocols.
+
+   $ Transport Layer Security (TLS)
+      (I) TLS Version 1.0 is an Internet protocol [R2246] based-on and
+      very similar to SSL Version 3.0. (See: TLSP.)
+
+
+
+Shirey                       Informational                    [Page 178]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (C) The TLS protocol is misnamed, because it operates well above
+      the transport layer (OSI layer 4).
+
+   $ Transport Layer Security Protocol (TLSP)
+      (I) An end-to-end encryption protocol(ISO Standard 10736) that
+      provides security services at the bottom of OSI layer 4, i.e.,
+      directly above layer 3. (See: TLS.)
+
+      (C) TLSP evolved directly from the SP4 protocol of SDNS.
+
+   $ transport mode vs. tunnel mode
+      (I) IPsec usage: Two ways to apply IPsec protocols (AH and ESP) to
+      protect communications:
+
+       - "Transport mode": The protection applies to (i.e., the IPsec
+         protocol encapsulates) the packets of upper-layer protocols,
+         the ones that are carried above IP.
+
+       - "Tunnel mode": The protection applies to (i.e., the IPsec
+         protocol encapsulates) IP packets.
+
+      (C) A transport mode security association is always between two
+      hosts. In a tunnel mode security association, each end may be
+      either a host or a gateway. Whenever either end of an IPsec
+      security association is a security gateway, the association is
+      required to be in tunnel mode.
+
+   $ trap door
+      (I) A hidden computer flaw known to an intruder, or a hidden
+      computer mechanism (usually software) installed by an intruder,
+      who can activate the trap door to gain access to the computer
+      without being blocked by security services or mechanisms. (See:
+      back door, Trojan horse.)
+
+   $ triple DES
+      (I) A block cipher, based on DES, that transforms each 64-bit
+      plaintext block by applying the Data Encryption Algorithm three
+      successive times, using either two or three different keys, for an
+      effective key length of 112 or 168 bits. [A9052] (See: DES.)
+
+      (C) IPsec usage: The algorithm variation proposed for ESP uses a
+      168-bit key, consisting of three independent 56-bit quantities
+      used by the Data Encryption Algorithm, and a 64-bit initialization
+      value. 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]
+
+
+
+
+
+Shirey                       Informational                    [Page 179]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ triple-wrapped
+      (I) S/MIME usage: Data that has been signed with a digital
+      signature, and then encrypted, and then signed again. [R2634]
+
+   $ 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.
+
+   $ trust
+      1. (I) Information system usage: The extent to which someone who
+      relies on a system can have confidence that the system meets its
+      specifications, i.e., that the system does what it claims to do
+      and does not perform unwanted functions. (See: trust level.)
+
+      (C) "trusted vs. trustworthy": In discussing a system or system
+      process or object, this Glossary (and industry usage) prefers the
+      term "trusted" to describe a system that operates as expected,
+      according to design and policy. When the trust can also be
+      guaranteed in some convincing way, such as through formal analysis
+      or code review, the system is termed "trustworthy"; this differs
+      from the ABA Guidelines definition (see: trustworthy system).
+
+      2. (I) PKI usage: 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.
+
+      (O) "Generally, an entity can be said to 'trust' a second entity
+      when it (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 and a
+      [certification] authority; an entity shall be certain that it can
+      trust the certification authority to create only valid and
+      reliable certificates." [X509]
+
+   $ trust chain
+      (D) ISDs SHOULD NOT use this term as a synonym for "certification
+      path" because it mixes concepts in a potentially misleading way.
+      (See: trust.)
+
+   $ trust-file PKI
+      (I) A non-hierarchical PKI in which each certificate user has a
+      local file (which is used by application software) of public-key
+      certificates that the user trusts as starting points (i.e., roots)
+      for certification paths. (See: hierarchical PKI, mesh PKI, root,
+      web of trust.)
+
+
+
+Shirey                       Informational                    [Page 180]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (C) For example, popular browsers are distributed with an initial
+      file of trusted 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) ISDs SHOULD NOT use this term as a synonym for "certification
+      hierarchy" because this term mixes concepts (see: trust) in a
+      potentially misleading way and duplicates the meaning of another,
+      standardized term. (See: trust, web of trust.)
+
+   $ trust level
+      (I) A characterization of a standard of security protection to be
+      met by a computer system.
+
+      (C) The TCSEC defines eight trust levels. From the lowest to the
+      highest, they are D, C1, C2, B1, B2, B3, and A1. A trust level is
+      based not only on the presence of security mechanisms but also on
+      the use of systems engineering discipline to properly structure
+      the system and implementation analysis to ensure that the system
+      provides an appropriate degree of trust.
+
+   $ trusted
+      See: (discussion under) trust.
+
+   $ trusted certificate
+      (I) A certificate upon which a certificate user relies as being
+      valid without the need for validation testing; especially a
+      public-key certificate that is used to provide the first public
+      key in a certification path. (See: certification path, root
+      certificate, validation.)
+
+      (C) 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)
+      any certificate accepted by the user in a trust-file PKI.
+
+   $ trusted computer system
+      (I) Multilevel security usage: "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: (discussion under) trust.)
+
+   $ Trusted Computer System Evaluation Criteria (TCSEC)
+      (N) A standard for evaluating the security provided by operating
+      systems [CSC001, DOD1]. Informally called the "Orange Book"
+
+
+
+
+Shirey                       Informational                    [Page 181]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      because of the color of its cover; first document in the Rainbow
+      Series. (See: Common Criteria, (usage note under) Green Book,
+      Orange Book, trust level.)
+
+   $ trusted computing base (TCB)
+      (I) "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: (discussion of "trusted" under) trust.)
+
+   $ trusted distribution
+      (I) "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]
+
+   $ trusted key
+      (I) A public key upon which a user relies; especially a public key
+      that can be used as the first public key in a certification path.
+      (See: certification path, root key, validation.)
+
+      (C) A trusted public key might 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 path
+      (I) COMPUSEC usage: A mechanism by which a computer system user
+      can communicate directly and reliably with the trusted computing
+      base (TCB) and that can only be activated by the user or the TCB
+      and cannot be imitated by untrusted software within the computer.
+      [NCS04]
+
+      (I) COMSEC usage: 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]
+
+   $ trusted process
+      (I) A system process 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, (discussion of "trusted" under)
+      trust.)
+
+
+
+
+
+
+Shirey                       Informational                    [Page 182]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ 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--e.g.,
+      telephone lines, or a LAN--are protected from attack by some
+      means.)
+
+   $ trusted system
+      See: (discussion under) trust, trusted computer system,
+      trustworthy system.
+
+   $ Trusted Systems Interoperability Group (TSIG)
+      (N) A forum of computer vendors, system integrators, and users
+      devoted to promoting interoperability of trusted computer systems.
+      TSIG meetings are open to all persons who are working in the
+      INFOSEC area.
+
+   $ trustworthy system
+      (O) ABA usage: "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." [ABA] This differs somewhat from other industry
+      usage. (See: (discussion of "trusted vs. trustworthy" under)
+      trust.)
+
+   $ TSIG
+      See: Trusted System Interoperability Group.
+
+   $ tunnel
+      (I) A communication channel created in a computer network by
+      encapsulating (carrying, layering) a communication protocol's data
+      packets in (on top of) a second protocol that normally would be
+      carried above, or at the same layer as, the first one. (See: L2TP,
+      VPN.)
+
+      (C) Tunneling can involve almost any OSI or TCP/IP protocol
+      layers; for example, a TCP connection between two hosts could
+      conceivably be tunneled through email messages across the
+      Internet. Most often, a tunnel is a logical point-to-point link--
+      i.e., an OSI layer 2 connection--created by encapsulating the
+      layer 2 protocol in a transport protocol (such as TCP), in a
+      network or internetwork layer protocol (such as IP), or in another
+      link layer protocol. Often, encapsulation is accomplished with an
+      extra, intermediate protocol, i.e., a tunneling protocol (such as
+      L2TP) that is layered between the tunneled layer 2 protocol and
+      the encapsulating protocol.
+
+
+
+Shirey                       Informational                    [Page 183]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (C) Tunneling can 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: virtual private network.)
+
+      (O) SET usage: 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) IPsec usage: See: transport mode vs. tunnel mode.
+
+   $ two-person control
+      (I) The close surveillance and control of a system, 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.)
+
+   $ Type I cryptography
+      (O) A cryptographic algorithm or device approved by NSA for
+      protecting classified information.
+
+   $ Type II cryptography
+      (O) A cryptographic algorithm or device approved by NSA for
+      protecting sensitive unclassified information (as specified in
+      section 2315 of Title 10 United States Code, or section 3502(2) of
+      Title 44, United States Code.)
+
+   $ Type III cryptography
+      (O) A cryptographic algorithm or device approved as a Federal
+      Information Processing Standard.
+
+   $ UDP
+      See: User Datagram Protocol.
+
+   $ unclassified
+      (I) Not classified.
+
+   $ unencrypted
+      (I) Not encrypted.
+
+
+
+
+
+
+Shirey                       Informational                    [Page 184]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ unforgeable
+      (I) Cryptographic usage: The property of a cryptographic data
+      structure (i.e., a data structure that is defined using one or
+      more cryptographic functions) 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. (E.g., see: digital certificate.)
+
+      (C) 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.
+
+   $ uniform resource identifier (URI)
+      (I) A type of formatted identifier 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. [R1630]
+
+      (C) URIs are used in HTML to identify the target of hyperlinks. In
+      common practice, URIs include uniform resource locators [R2368]
+      and relative URLs, and may be URNs. [R1808]
+
+   $ uniform resource locator (URL)
+      (I) A type of formatted identifier that describes the access
+      method and location of an information resource object on the
+      Internet. [R1738]
+
+      (C) A URL is a URI that 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.
+
+
+
+
+
+Shirey                       Informational                    [Page 185]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ uniform resource name (URN)
+      (I) A URI that has an institutional commitment to persistence and
+      availability.
+
+   $ untrusted process
+      (I) A system process that is not able to affect the state of
+      system security through incorrect or malicious operation, usually
+      because its operation is confined by a security kernel. (See:
+      trusted process.)
+
+   $ UORA
+      See: user-PIN ORA.
+
+   $ update
+      See: certificate update and key update.
+
+   $ URI
+      See: uniform resource identifier.
+
+   $ URL
+      See: uniform resource locator.
+
+   $ URN
+      See: uniform resource name.
+
+   $ user
+      (I) A person, organization entity, or automated process that
+      accesses a system, whether authorized to do so or not. (See:
+      [R2504].)
+
+      (C) Any ISD that uses this term SHOULD provide an explicit
+      definition, because this term is used in many ways and can easily
+      be misunderstood.
+
+   $ User Datagram Protocol (UDP)
+      (I) An Internet Standard protocol [R0768] that provides a datagram
+      mode of packet-switched computer communication in an internetwork.
+
+      (C) UDP is a transport layer protocol, and it 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 services that TCP provides.
+
+   $ user identifier
+      (I) A character string or symbol that is used in a system to
+      uniquely name a specific user or group of users.
+
+
+
+
+Shirey                       Informational                    [Page 186]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (C) Often verified by a password in an authentication process.
+
+   $ user PIN
+      (O) MISSI usage: One of two personal identification numbers that
+      control access to the functions and stored data of a FORTEZZA PC
+      card. Knowledge of the user PIN enables the card user to perform
+      the FORTEZZA functions that are intended for use by an end user.
+      (See: SSO PIN.)
+
+   $ user-PIN ORA (UORA)
+      (O) 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
+      See: (secondary definition under) threat consequence.
+
+   $ 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. Note: UTCTime
+      has the Year 2000 problem. (See: Coordinated Universal Time,
+      GeneralizedTime.)
+
+   $ v1 certificate
+      (C) Ambiguously refers to either an X.509 public-key certificate
+      in its version 1 format, or an X.509 attribute certificate in its
+      version 1 format. However, many people who use this term are not
+      aware that X.509 specifies attribute certificates that do not
+      contain a public key. Therefore, ISDs MAY use this term as an
+      abbreviation for "version 1 X.509 public-key certificate", but
+      only after using the full term at the first instance.
+
+      (D) ISDs SHOULD NOT use this term as an abbreviation for "version
+      1 X.509 attribute certificate".
+
+   $ v1 CRL
+      (I) An abbreviation for "X.509 CRL in version 1 format".
+
+      (C) ISDs should use this abbreviation only after using the full
+      term at its first occurrence and defining the abbreviation.
+
+   $ v2 certificate
+      (I) An abbreviation for "X.509 public-key certificate in version 2
+      format".
+
+
+
+Shirey                       Informational                    [Page 187]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (C) ISDs should use this abbreviation only after using the full
+      term at its first occurrence and defining the abbreviation.
+
+   $ v2 CRL
+      (I) An abbreviation for "X.509 CRL in version 2 format".
+
+      (C) ISDs should use this abbreviation only after using the full
+      term at its first occurrence and defining the abbreviation.
+
+   $ v3 certificate
+      (I) An abbreviation for "X.509 public-key certificate in version 3
+      format".
+
+      (C) ISDs should use this abbreviation only after using the full
+      term at its first occurrence and defining the abbreviation.
+
+   $ valid certificate
+      (I) A digital certificate for which the binding of the data items
+      can be trusted; one that can be validated successfully. (See:
+      validate vs. verify.)
+
+   $ valid signature
+      (D) ISDs SHOULD NOT use this term; instead, use "authentic
+      signature". 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
+      vs. verify.)
+
+   $ validate vs. verify
+      (C) The PKI community uses words inconsistently when describing
+      what a certificate user does to make certain that a digital
+      certificate can be trusted. Usually, we say "verify the signature"
+      but say "validate the certificate"; i.e., we "verify" atomic
+      truths but "validate" data structures, relationships, and systems
+      that are composed of or depend on verified items. Too often,
+      however, verify and validate are used interchangeably.
+
+      ISDs SHOULD comply with the following two rules to ensure
+      consistency and to align Internet security terminology with
+      ordinary English:
+
+       - Rule 1: Use "validate" when referring to a process intended to
+         establish the soundness or correctness of a construct. (E.g.,
+         see: certificate validation.)
+
+       - 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.,
+         see: authenticate.)
+
+
+
+Shirey                       Informational                    [Page 188]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      The rationale for Rule 1 is that "valid" derives from a word that
+      means "strong" in Latin. Thus, to validate means to make sure that
+      a construction is sound. A certificate user validates a public-key
+      certificate to establish trust in the binding that the certificate
+      asserts between an identity and a key. (To validate can also mean
+      to officially approve something; e.g., NIST validates
+      cryptographic modules for conformance with FIPS PUB 140-1.)
+
+      The rationale for Rule 2 is that "verify" derives from a word that
+      means "true" in Latin. Thus, to verify means to prove the truth of
+      an assertion by examining evidence or performing tests. 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
+      current time is within the certificate's validity period; and may
+      need to validate a certification path involving additional
+      certificates.
+
+   $ validation
+      See: validate vs. verify.
+
+   $ validity period
+      (I) 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.
+
+   $ value-added network (VAN)
+      (I) A computer network or subnetwork (which is usually a
+      commercial enterprise) that transmits, receives, and stores EDI
+      transactions on behalf of its customers.
+
+      (C) A VAN may also provide additional services, ranging from EDI
+      format translation, to EDI-to-FAX conversion, to integrated
+      business systems.
+
+   $ VAN
+      See: value-added network.
+
+   $ verification
+      1. System verification: The process of comparing two levels of
+      system specification for proper correspondence, such as comparing
+      a security policy with a top-level specification, a top-level
+      specification with source code, or source code with object code.
+      [NCS04]
+
+
+
+
+Shirey                       Informational                    [Page 189]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      2. Identification verification: Presenting information to
+      establish the truth of a claimed identity.
+
+   $ verify
+      See: validate vs. verify.
+
+   $ 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 (such as the
+      Internet), often by using encryption (located at hosts or
+      gateways), and often by tunneling links of the virtual network
+      across the real network.
+
+      (C) 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 (a) using encrypted tunnels to
+      connect from firewall to firewall across the Internet and (b) not
+      allowing any other traffic through the firewalls. 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 real network.
+
+   $ virus
+      (I) A hidden, self-replicating 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.
+
+   $ VPN
+      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.
+
+      (C) Most systems have vulnerabilities of some sort, but 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
+
+
+
+Shirey                       Informational                    [Page 190]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      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 benefit for someone to make an attack.
+
+   $ W3
+      See: World Wide Web.
+
+   $ war dialer
+      (I) 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 into the
+      systems.
+
+   $ 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.)
+
+      (C) The Arrangement began operations in September 1996. The
+      participating countries are 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 Federation, Slovak Republic,
+      Spain, Sweden, Switzerland, Turkey, Ukraine, United Kingdom, and
+      United States. Participants meet on a regular basis in Vienna,
+      where the Arrangement has its headquarters.
+
+      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
+
+
+
+Shirey                       Informational                    [Page 191]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      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.
+
+   $ web of trust
+      (O) PGP usage: A trust-file PKI technique used in PGP for building
+      a file of validated public keys by making personal judgments about
+      being able to trust certain people to be holding properly
+      certified keys of other people. (See: certification hierarchy,
+      mesh PKI.)
+
+   $ web server
+      (I) A software process that runs on a host computer connected to
+      the Internet to respond to HTTP requests for documents from client
+      web browsers.
+
+   $ web vs. Web
+      1. (I) Capitalized: ISDs 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 vs. Internet.)
+
+      2. (C) Not capitalized: ISDs 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.
+
+      (C) IETF documents SHOULD spell out "World Wide Web" fully at the
+      first instance of usage and SHOULD Use "Web" and "web" especially
+      carefully where confusion with the PGP "web of trust" is possible.
+
+   $ wiretapping
+      (I) An attack that intercepts and accesses data and other
+      information contained in a flow in a communication system.
+
+      (C) 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 reading information from any sort of medium
+      used for a link or even directly from a node, such as gateway or
+      subnetwork switch.
+
+
+
+
+
+Shirey                       Informational                    [Page 192]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      (C) "Active wiretapping" attempts to alter the data or otherwise
+      affect the flow; "passive wiretapping" only attempts to observe
+      the flow and gain knowledge of information it contains. (See:
+      active attack, end-to-end encryption, passive attack.)
+
+   $ work factor
+      (I) General security usage: 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.
+
+      (I) Cryptography usage: The estimated amount of computing time and
+      power needed to break a cryptographic system.
+
+   $ World Wide Web ("the Web", WWW, W3)
+      (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].)
+
+   $ 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 computer resources destructively. (See: Morris
+      Worm, virus.)
+
+   $ wrap
+      (O) To use cryptography to provide data confidentiality service
+      for a data object. (See: encrypt, seal.)
+
+      (D) ISDs SHOULD NOT use this term with this definition because it
+      duplicates the meaning of other, standard terms. Instead, use
+      "encrypt" or use a term that is specific with regard to the
+      mechanism used.
+
+   $ WWW
+      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
+   $ X.500 Directory
+      (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
+
+
+
+Shirey                       Informational                    [Page 193]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      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.)
+
+      (C) 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 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 services, 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.)
+
+      (C) X.509 describes two levels of authentication: simple
+      authentication based on a password, and strong authentication
+      based on a public-key certificate.
+
+   $ 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.)
+
+      (C) 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.
+
+      (C) An X.509 attribute certificate contains a sequence of data
+      items and has a digital signature that is computed from that
+      sequence. In addition to the signature, an attribute certificate
+      contains items 1 through 9 listed below:
+
+
+
+
+
+
+Shirey                       Informational                    [Page 194]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      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".
+      7. attributes             Sequence of attributes describing the
+                                subject.
+      8. issuerUniqueId         Optional, when a DN is not sufficient.
+      9. extensions             Optional.
+
+   $ X.509 authority revocation list
+      (N) An ARL in one of the formats defined by X.509--version 1 (v1)
+      or version 2 (v2). A specialized kind of certificate revocation
+      list.
+
+   $ X.509 certificate
+      (N) Either an X.509 public-key certificate or an X.509 attribute
+      certificate.
+
+      (C) This Glossary uses the term with the precise meaning
+      recommended here. However, some who use the term may not be aware
+      that X.509 specifies attribute certificates that do not contain a
+      public key. Even among those who are aware, this term is commonly
+      used as an abbreviation to mean "X.509 public-key certificate".
+      ISDs MAY use the term as an abbreviation for "X.509 public-key
+      certificate", but only after using the full term at the first
+      instance.
+
+      (D) ISDs SHOULD NOT use this term as an abbreviation to mean
+      "X.509 attribute certificate".
+
+   $ 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.)
+
+      (C) ISDs SHOULD NOT refer to an X.509 CRL as a digital
+      certificate, but note that an X.509 CRL does meet this Glossary's
+      definition of "digital certificate". Like a digital certificate,
+
+
+
+Shirey                       Informational                    [Page 195]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+      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.
+
+      (C) An X.509 CRL contains a sequence of data items and has a
+      digital signature computed on that sequence. In addition to 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.
+      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.)
+
+      (C) An X.509 public-key certificate contains a sequence of data
+      items and has a digital signature computed on that sequence. In
+      addition to 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.
+
+
+
+
+Shirey                       Informational                    [Page 196]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   $ XTACACS
+      See: (secondary definition under) Terminal Access Controller (TAC)
+      Access Control System.
+
+   $ Yellow Book
+      (D) ISDs SHOULD NOT use this term as a synonym for "Computer
+      Security Requirements: Guidance for Applying the Department of
+      Defense Trusted Computer System Evaluation Criteria in Specific
+      Environments" [CSC3]. Instead, use the full proper name of the
+      document or, in subsequent references, a conventional
+      abbreviation. (See: (usage note under) Green Book, Rainbow
+      Series.)
+
+   $ zeroize
+      (I) Use erasure or other means to render stored data unusable and
+      unrecoverable, particularly a key stored in a cryptographic module
+      or other device.
+
+      (O) Erase electronically stored data by altering the contents of
+      the data storage so as to prevent the recovery of the data.
+      [FP140]
+
+4. References
+
+   This Glossary focuses on the Internet Standards Process. Therefore,
+   this set of references emphasizes international, governmental, and
+   industry standards documents; only a few other texts are listed. RFCs
+   are listed, but not Internet-Drafts, because the latter are not an
+   archival document series and should not be cited or quoted in an RFC.
+
+   [A3092]  American National Standards Institute, "American National
+            Standard Data Encryption Algorithm", ANSI X3.92-1981, 30 Dec
+            1980.
+
+   [A9009]  ---, "Financial Institution Message Authentication
+            (Wholesale)", ANSI X9.9-1986, 15 Aug 1986.
+
+   [A9017]  ---, "Financial Institution Key Management (Wholesale)",
+            X9.17, 4 Apr 1985. [Defines procedures for the 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 Jan 1999.
+
+
+
+
+
+Shirey                       Informational                    [Page 197]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   [A9052]  ---, "Triple Data Encryption Algorithm Modes of Operation",
+            X9.52-1998, ANSI approval 9 Nov 1998.
+
+   [A9062]  ---, "Public Key Cryptography for the Financial Services
+            Industry: The Elliptic Curve Digital Signature Algorithm
+            (ECDSA)", X9.62-1998, ANSI approval 7 Jan 1999.
+
+   [ABA]    American Bar Association, "Digital Signature Guidelines:
+            Legal Infrastructure for Certification Authorities and
+            Secure Electronic Commerce", Chicago, IL, 1 Aug 1996.
+
+   [ACM]    Association for Computing Machinery, "Communications of the
+            ACM", Jul 1998 issue with: Minerva M. Yeung, "Digital
+            Watermarking"; Nasir Memom and Ping Wah Wong, "Protecting
+            Digital Media Content"; and Scott Craver, Boon-Lock Yeo, and
+            Minerva Yeung, "Technical Trials and Legal Tribulations".
+
+   [Army]   U.S. Army Corps of Engineers, "Electromagnetic Pulse (EMP)
+            and Tempest Protection for Facilities", EP 1110-3-2, 31 Dec
+            1990.
+
+   [B7799]  British Standards Institution, "Information Security
+            Management, Part 1: Code of Practice for Information
+            Security Management", BS 7799-1:1999, effective 15 May 1999.
+
+            ---, ---, "Part 2: Specification for Information Security
+            Management Systems", BS 7799-2:1999, effective 15 May 1999.
+
+   [Bell]   D. E. Bell and L. J. 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.)
+
+   [CCIB]   Common Criteria Implementation Board, "Common Criteria for
+            Information Technology Security Evaluation, Part 1:
+            Introduction and General Model", ver. 2.1, CCIB-99-01, Aug
+            1999.
+
+   [CIPSO]  Trusted Systems Interoperability Working Group, "Common IP
+            Security Option", ver. 2.3, 9 Mar 1993. [A "work in
+            progress" that is probably defunct.]
+
+   [CSC1]   U.S. Department of Defense Computer Security Center,
+            "Department of Defense Trusted Computer System Evaluation
+            Criteria", CSC-STD-001-83, 15 Aug 1983. (Superseded by
+            [DOD1].)
+
+
+
+
+
+Shirey                       Informational                    [Page 198]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   [CSC2]   ---, "Department of Defense Password Management Guideline",
+            CSC-STD-002-85, 12 Apr 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 Jun
+            1985.
+
+   [CSOR]   U.S. Department of Commerce, "General Procedures for
+            Registering Computer Security Objects", National Institute
+            of Standards Interagency Report 5308, Dec 1993.
+
+   [Denn]   D. E. Denning, "A Lattice Model of Secure Information Flow",
+            in "Communications of the ACM", vol. 19, no. 5, May 1976,
+            pp. 236-243.
+
+   [DH76]   W. Diffie and M. H. Hellman, "New Directions in
+            Cryptography" in "IEEE Transactions on Information Theory",
+            vol. IT-22, no. 6, Nov 1976, pp. 644-654.
+
+   [DOD1]   U.S. Department of Defense, "Department of Defense Trusted
+            Computer System Evaluation Criteria", DoD 5200.28-STD, 26
+            Dec 1985. (Supersedes [CSC1].)
+
+   [DOD2]   ---, Directive 5200.28, "Security Requirements for Automated
+            Information Systems (AISs)", 21 Mar 1988.
+
+   [DOD3]   ---, "X.509 Certificate Policy", ver. 2, Mar 1999.
+
+   [DOD4]   ---, "NSA Key Recovery Assessment Criteria", 8 Jun 1998.
+
+   [ElGa]   T. El Gamal, "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", ver. 3.1.1, 31 May 1998.
+
+   [EMV2]   ---, "EMV '96 Integrated Circuit Card Terminal Specification
+            for Payment Systems", ver. 3.1.1, 31 May 1998.
+
+   [EMV3]   ---, EMV '96 Integrated Circuit Card Application
+            Specification for Payment Systems", ver. 3.1.1, 31 May 1998.
+
+
+
+
+
+Shirey                       Informational                    [Page 199]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   [For94]  W. Ford, "Computer Communications Security: Principles,
+            Standard Protocols and Techniques", ISBN 0-13-799453-2,
+            1994.
+
+   [For97]  W. Ford and M. Baum, "Secure Electronic Commerce: Building
+            the Infrastructure for Digital Signatures and Encryption",
+            ISBN 0-13-476342-4, 1994.
+
+   [FP031]  U.S. Department of Commerce, "Guidelines for Automatic Data
+            Processing Physical Security and Risk Management", Federal
+            Information Processing Standards Publication (FIPS PUB) 31,
+            Jun 1974.
+
+   [FP039]  ---, "Glossary for Computer Systems Security", FIPS PUB 39,
+            15 Feb 1976.
+
+   [FP046]  ---, "Data Encryption Standard (DES)", FIPS PUB 46-2, 30 Dec
+            1993.
+
+   [FP081]  ---, "DES Modes of Operation", FIPS PUB 81, 2 Dec 1980.
+
+   [FP102]  ---, "Guideline for Computer Security Certification and
+            Accreditation", FIPS PUB 102, 27 Sep 1983.
+
+   [FP113]  ---, "Computer Data Authentication", FIPS PUB 113, 30 May
+            1985.
+
+   [FP140]  ---, "Security Requirements for Cryptographic Modules", FIPS
+            PUB 140-1, 11 Jan 1994.
+
+   [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 180-1, 17 Apr 1995.
+
+   [FP185]  ---, "Escrowed Encryption Standard", FIPS PUB 185, 9 Feb
+            1994.
+
+   [FP186]  ---, "Digital Signature Standard (DSS)", FIPS PUB 186, 19
+            May 1994.
+
+   [FP188]  ---, "Standard Security Label for Information Transfer",
+            FIPS PUB 188, 6 Sep 1994.
+
+   [FPDAM]  Collaborative ITU and ISO/IEC meeting on the Directory,
+            "Final Proposed Draft Amendment on Certificate Extensions",
+            April 1999. (This draft proposes changes to [X.509].)
+
+
+
+Shirey                       Informational                    [Page 200]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   [FPKI]   U.S. Department of Commerce, "Public Key Infrastructure
+            (PKI) Technical Specifications: Part A--Technical Concept of
+            Operations", National Institute of Standards, 4 Sep 1998.
+
+   [I3166]  International Standards Organization, "Codes for the
+            Representation of Names of countries and Their Subdivisions
+            --Part 1: Country Codes", ISO 3166-1:1997.
+
+            ---, --- "Part 2: Country Subdivision Codes", ISO/DIS 3166-
+            2.
+
+            ---, --- "Part 3: Codes for Formerly Used Names of
+            Countries", ISO/DIS 3166-3.
+
+   [I7498]  ---, "Information Processing Systems--Open Systems
+            Interconnection Reference Model--[Part 1:] Basic Reference
+            Model", ISO/IEC 7498-1. (Equivalent to ITU-T Recommendation
+            X.200.)
+
+            ---, --- "Part 2: Security Architecture", ISO/IEC 7499-2.
+
+            ---, --- "Part 4: Management Framework", ISO/IEC 7498-4.
+
+   [I7812]  ---, "Identification cards--Identification of Issuers--Part
+            1: Numbering System", ISO/IEC 7812-1:1993
+
+            ---, --- "Part 2: Application and Registration Procedures",
+            ISO/IEC 7812-2:1993.
+
+   [I9945]  ---, "Portable Operating System Interface for Computer
+            Environments", ISO/IEC 9945-1:1990.
+
+   [I15408] ---, "Information Technology--Security Techniques--
+            Evaluation criteria for IT Security--Part 1: Introduction
+            and General Model", ISO/IEC 15408-1:1999.
+
+   [ITSEC]  "Information Technology Security Evaluation Criteria
+            (ITSEC): Harmonised Criteria of France, Germany, the
+            Netherlands, and the United Kingdom", ver. 1.2, U.K.
+            Department of Trade and Industry, Jun 1991.
+
+   [Kahn]   David Kahn, "The Codebreakers: The Story of Secret Writing",
+            The Macmillan Company, New York, 1967.
+
+   [Knuth]  D. E. Knuth, Chapter 3 ("Random Numbers") in Volume 2
+            ("Seminumerical Algorithms") of "The Art of Computer
+            Programming", Addison-Wesley, Reading, MA, 1969.
+
+
+
+
+Shirey                       Informational                    [Page 201]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   [Kuhn]   Markus G. Kuhn and Ross J. 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
+            Apr 1998, LNCS 1525, Springer-Verlag, ISBN 3-540-65386-4,
+            pp. 124-142.
+
+   [MISPC]  U.S. Department of Commerce, "Minimum Interoperability
+            Specification for PKI Components (MISPC), Version 1",
+            National Institute of Standards Special Publication 800-15,
+            Sep 1997.
+
+   [NCS01]  National Computer Security Center, "A Guide to Understanding
+            Audit in Trusted Systems", NCSC-TG-001, 1 Jun 1988. (Part of
+            the Rainbow Series.)
+
+   [NCS04]  ---, "Glossary of Computer Security Terms", NCSC-TG-004,
+            ver. 1, 21 Oct 1988. (Part of the Rainbow Series.)
+
+   [NCS05]  ---, "Trusted Network Interpretation of the Trusted Computer
+            System Evaluation Criteria", NCSC-TG-005, ver. 1, 31 Jul
+            1987. (Part of the Rainbow Series.)
+
+   [NCS25]  ---, "A Guide to Understanding Data Remanence in Automated
+            Information Systems", NCSC-TG-025, ver. 2, Sep 1991. (Part
+            of the Rainbow Series.)
+
+   [NIST]   National Institute of Standards and Technology, "SKIPJACK
+            and KEA Algorithm Specifications", ver. 2, 29 May 1998.
+            (http://csrc.nist.gov/encryption/skipjack-kea.htm)
+
+   [PGP]    Simson Garfinkel, "PGP: Pretty Good Privacy", O'Reilly &
+            Associates, Inc., Sebastopol, CA, 1995.
+
+   [PKCS]   Burton S. Kaliski, Jr., "An Overview of the PKCS Standards",
+            RSA Data Security, Inc., 3 Jun 1991.
+
+   [PKC07]  RSA Laboratories, "PKCS #7: Cryptographic Message Syntax
+            Standard", ver. 1.5, RSA Laboratories Technical Note, 1 Nov
+            1993.
+
+   [PKC10]  ---, "PKCS #10: Certification Request Syntax Standard", ver.
+            1.0, RSA Laboratories Technical Note, 1 Nov 1993.
+
+   [PKC11]  ---, "PKCS #11: Cryptographic Token Interface Standard",
+            ver. 1.0, 28 Apr 1995.
+
+
+
+
+
+Shirey                       Informational                    [Page 202]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   [R0768]  Postel, J., "User Datagram Protocol", STD 6, RFC 768, August
+            1980.
+
+   [R0791]  Postel, J., "Internet Protocol", STD 5, RFC 791, September
+            1981.
+
+   [R0792]  Postel, J., "Internet Control Message Protocol", STD 5, RFC
+            792, September 1981. [See: RFC 1885.]
+
+   [R0793]  Postel, J., ed., "Transmission Control Protocol", STD 7, RFC
+            793, September 1981.
+
+   [R0821]  Postel, J., "Simple Mail Transfer Protocol", STD 10, RFC
+            821, August 1982.
+
+   [R0822]  Crocker, D., "Standard for the Format of ARPA Internet Text
+            Messages", STD 11, RFC 822, August 1982.
+
+   [R0854]  Postel, J. and J. Reynolds, "TELNET Protocol Specification",
+            STD 8, RFC 854, May 1983.
+
+   [R0959]  Postel, J. and J. Reynolds, "File Transfer Protocol (FTP)",
+            STD 9, RFC 959, October 1985.
+
+   [R1034]  Mockapetris, P., "Domain Names--Concepts and Facilities",
+            STD 13, RFC 1034, November 1987.
+
+   [R1157]  Case, J., Fedor, M., Schoffstall, M. and J. Davin, "A Simple
+            Network Management Protocol (SNMP)" [version 1], STD 15, RFC
+            1157, May 1990.
+
+   [R1208]  Jacobsen O. and D. Lynch, "A Glossary of Networking Terms",
+            RFC 1208, March 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.
+
+   [R1321]  Rivest, R., "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.
+
+
+
+Shirey                       Informational                    [Page 203]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   [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, 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.
+
+   [R1510]  Kohl, J. and C. Neuman, "The Kerberos Network Authentication
+            Service (V5)", RFC 1510, September 1993.
+
+   [R1591]  Kohl, J. and C. Neuman, "Domain Name System Structure and
+            Delegation", March 1994.
+
+   [R1630]  Berners-Lee, T., "Universal Resource Identifiers in WWW",
+            RFC 1630, June 1994.
+
+   [R1661]  Simpson, W., ed., " The Point-to-Point Protocol (PPP)", STD
+            51, RFC 1661, July 1994.
+
+   [R1731]  Myers, J., "IMAP4 Authentication Mechanisms", RFC 1731,
+            December 1994.
+
+   [R1734]  Myers, J., "POP3 AUTHentication Command", RFC 1734, December
+            1994.
+
+   [R1738]  Myers, J., Masinter, L. and M. McCahill, ed's., "Uniform
+            Resource Locators (URL)", RFC 1738, December 1994.
+
+   [R1750]  Eastlake, D., Crocker, S. and J. Schiller, "Randomness
+            Recommendations for Security", RFC 1750, December 1994.
+
+   [R1777]  Yeong, W., Howes, T. and S. Kille, "Lightweight Directory
+            Access Protocol", RFC 1777, March 1995.
+
+
+
+
+
+Shirey                       Informational                    [Page 204]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   [R1808]  Fielding, R., "Relative Uniform Resource Locators", RFC
+            1808, June 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.
+
+   [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.
+
+   [R1866]  Berners-Lee, T., "Hypertext Markup Language--2.0", RFC 1866,
+            November 1995.
+
+   [R1885]  Conta, A. and S. Deering, "Internet Control Message Protocol
+            (ICMPv6) for the Internet Protocol Version 6 (IPv6)
+            Specification", RFC 1885, December 1995.
+
+   [R1928]  Leech, M., Ganis, M., Lee, Y., Kuris, R., Koblas, D. and L.
+            Jones, "SOCKS Protocol Version 5", RFC 1928, March 1996.
+
+   [R1938]  Haller, N. and C. Metzion, "A One-Time Password System", RFC
+            1938, May 1996.
+
+   [R1939]  Myers, J. and M. Rose, "Post Office Protocol - Version 3",
+            STD 53, RFC 1939, May 1996.
+
+   [R1958]  Carpenter, B., ed., "Architectural Principles of the
+            Internet", RFC 1958, June 1996.
+
+   [R1983]  Malkin, G., ed., "Internet Users' Glossary", FYI 18, RFC
+            1983, August 1996.
+
+   [R1994]  Simpson, W. "PPP Challenge Handshake Authentication Protocol
+            (CHAP)", RFC 1994, August 1996.
+
+   [R2023]  Postel, J. and J. Reynolds, "Instructions to RFC Authors",
+            RFC 2023, October 1997.
+
+
+
+
+
+Shirey                       Informational                    [Page 205]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   [R2026]  Bradner, S., "The Internet Standards Process--Revision 3",
+            BCP 9, RFC 2026, March 1994.
+
+   [R2045]  Freed, N. and N. Borenstein, "Multipurpose Internet Mail
+            Extensions (MIME) Part One: Format of Internet Message
+            Bodies", RFC 2045, November 1996.
+
+   [R2060]  Crispin, M., "Internet Message Access Protocol--Version 4
+            Revision 1", RFC 2060, December 1996.
+
+   [R2065]  Eastlake, D., 3rd, "Domain Name System Security Extensions",
+            RFC 2065, January 1997.
+
+   [R2078]  Linn, J., "Generic Security Service Application Program
+            Interface, Version 2", RFC 2078, January 1997.
+
+   [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.
+
+   [R2119]  Bradner, S., "Key Words for Use in RFCs To Indicate
+            Requirement Levels", BCP 14, RFC 2119, March 1997.
+
+   [R2138]  Rigney, C., Rubens, A., Simpson, W. and S. Willens, "Remote
+            Authentication Dial In User Service (RADIUS)", RFC 2138,
+            April 1997.
+
+   [R2137]  Eastlake, D., "Secure Domain Name System Dynamic Update",
+            RFC 2137, April 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, Sepember
+            1997.
+
+   [R2196]  Fraser, B., "Site Security Handbook", FYI 8, RFC 2196,
+            Sepember 1997.
+
+   [R2202]  Cheng, P. and R. Glenn, "Test Cases for HMAC-MD5 and HMAC-
+            SHA-1", RFC 2202, Sepember 1997.
+
+
+
+
+
+
+Shirey                       Informational                    [Page 206]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   [R2222]  Myers, J., "Simple Authentication and Security Layer
+            (SASL)", RFC 2222, October 1997.
+
+   [R2223]  Postel, J., "Instructions to RFC Authors", RFC 2223, October
+            1997.
+
+   [R2246]  Dierks, T. and C. Allen, "The TLS Protocol, Version 1.0",
+            RFC 2246, January 1999.
+
+   [R2284]  Blunk, L. and J. Vollbrecht, "PPP Extensible Authentication
+            Protocol (EAP)", RFC 2284, March 1998.
+
+   [R2315]  Kaliski, B., "PKCS #7: Cryptographic Message Syntax, Version
+            1.5", RFC 2315, March 1998.
+
+   [R2323]  Ramos, A., "IETF Identification and Security Guidelines",
+            RFC 2323, 1 April 1998. [Intended for humorous entertainment
+            ("please laugh loud and hard"); does not contain serious
+            security information.]
+
+   [R2350]  Brownlee, N. and E. Guttman, "Expectations for Computer
+            Security Incident Response", RFC 2350, June 1998.
+
+   [R2356]  Montenegro, C. and V. Gupta, "Sun's SKIP Firewall Traversal
+            for Mobile IP", RFC 2356, June 1998.
+
+   [R2373]  Hinden, R. and S. Deering, "IP Version 6 Addressing
+            Architecture", RFC 2373, July 2998.
+
+   [R2401]  Kent, S. and R. Atkinson, "Security Architecture for the
+            Internet Protocol", RFC 2401, November 1998.
+
+   [R2402]  Kent, S. and R. Atkinson, "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]  Madson, C. and R. Glenn, "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.
+
+
+
+
+
+Shirey                       Informational                    [Page 207]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   [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.
+
+   [R2409]  Harkins, D. and D. Carrel, "The Internet Key Exchange
+            (IKE)", RFC 2409, 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.
+
+   [R2460]  Deering, S. and R. Hinden, "Internet Protocol, Version 6
+            (IPv6) Specification", RFC 2460, December 1998.
+
+   [R2504]  Guttman, E., Leong, L. and G. Malkin, "Users' Security
+            Handbook", RFC 2504, February 1999.
+
+   [R2510]  Adams, C. and S. Farrell, "Internet X.509 Public Key
+            Infrastructure Certificate Management Protocols", RFC 2510,
+            March 1999.
+
+   [R2527]  Chokhani, S. and W. Ford, "Internet X.509 Public Key
+            Infrastructure, Certificate Policy and Certification
+            Practices Framework", RFC 2527, March 1999.
+
+   [R2536]  EastLake, D., "DSA KEYs and SIGs in the Domain Name System
+            (DNS)", RFC 2536, March 1999.
+
+   [R2570]  Case, J., Mundy, R., Partain, D. and B. Stewart,
+            "Introduction to Version 3 of the Internet-Standard Network
+            Management Framework", RFC 2570, April 1999.
+
+   [R2574]  Blumenthal, U. and B. Wijnen, "User-based Security Model
+            (USM) for Version 3 of the Simple Network Management
+            Protocol (SNMPv3)", RFC 2574, April 1999.
+
+   [R2612]  Adams, C. and J. Gilchrist, "The CAST-256 Encryption
+            Algorithm", RFC 2612, June 1999.
+
+
+
+
+
+Shirey                       Informational                    [Page 208]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   [R2616]  Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter,
+            L., Leach, P. and T. Berners-Lee, "Hypertext Transfer
+            Protocol-- HTTP/1.1", RFC 2616, June 1999.
+
+   [R2628]  Smyslov, V., "Simple Cryptographic Program Interface", RFC
+            2628, June 1999.
+
+   [R2630]  Housley, R., "Cryptographic Message Syntax", RFC 2630, June
+            1999.
+
+   [R2631]  Rescorla, E., "Diffie-Hellman Key Agreement Method", RFC
+            2631, June 1999.
+
+   [R2633]  Ramsdell, B., ed., "S/MIME Version 3 Message Specification",
+            RFC 2633, June 1999.
+
+   [R2634]  Hoffman, P., ed., "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.
+
+   [Raym]   E. S. Raymond, ed., "The On-Line Hacker Jargon File", ver.
+            4.0.0, 24 Jul 1996. (Also available as "The New Hacker's
+            Dictionary", 2nd edition, MIT Press, Sep 1993, ISBN 0-262-
+            18154-1. See: http://www.tuxedo.org/jargon/ for the latest
+            version.)
+
+   [Russ]   D. Russell and G. T. Gangemi Sr., Chapter 10 ("TEMPEST") in
+            "Computer Security Basics", ISBN 0-937175-71-4, 1991.
+
+   [Schn]   B. Schneier, "Applied Cryptography", John Wiley & Sons,
+            Inc., New York, 1994.
+
+   [SDNS3]  U.S. Department of Defense, National Security Agency,
+            "Secure Data Network Systems, Security Protocol 3 (SP3)",
+            document SDN.301, Revision 1.5, 15 May 1989.
+
+   [SDNS4]  ---, ---, "Security Protocol 4 (SP4)", document SDN.401,
+            Revision 1.2, 12 Jul 1988.
+
+   [SDNS7]  ---, ---, "Secure data Network System, Message Security
+            Protocol (MSP)", document SDN.701, Revision 4.0, 7 Jun 1996,
+            with Corrections to Message Security Protocol, SDN.701, Rev
+            4.0", 96-06-07, 30 Aug, 1996.
+
+
+
+
+
+Shirey                       Informational                    [Page 209]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+   [SET1]   MasterCard and Visa, "SET Secure Electronic Transaction
+            Specification, Book 1: Business Description", ver. 1.0, 31
+            May 1997.
+
+   [SET2]   ---, "SET Secure Electronic Transaction Specification, Book
+            2: Programmer's Guide", ver. 1.0, 31 May 1997.
+
+   [Stei]   J. Steiner, C. Neuman, and J. Schiller, "Kerberos: An
+            Authentication Service for Open Network Systems" in "Usenix
+            Conference Proceedings", Feb 1988.
+
+   [X400]   International Telecommunications Union--Telecommunication
+            Standardization Sector (formerly "CCITT"), Recommendation
+            X.400, "Message Handling Services: Message Handling System
+            and Service Overview".
+
+   [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". (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 Nov 1994. (Equivalent to ISO/IEC 8824-1.)
+
+   [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 Nov 1994. (Equivalent to ISO/IEC 8825-1.)
+
+
+
+
+
+
+
+
+Shirey                       Informational                    [Page 210]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+5. Security Considerations
+
+   This document only defines security terms and recommends how to use
+   them. It does not describe in detail the vulnerabilities of, threats
+   to, or mechanisms that protect specific Internet protocols.
+
+6. Acknowledgments
+
+   Pat Cain, Mike Kong, and Charles Lynn provided meticulous comments on
+   an early draft.
+
+7. Author's Address
+
+   Please address all comments to:
+
+   Robert W. Shirey                   GTE / BBN Technologies
+   EMail: rshirey@bbn.com             Suite 1200, Mail Stop 30/12B2
+   Phone: +1 (703) 284-4641           1300 Seventeenth Street North
+   Fax:   +1 (703) 284-2766           Arlington, VA  22209-3801 USA
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Shirey                       Informational                    [Page 211]
+
+RFC 2828               Internet Security Glossary               May 2000
+
+
+8. Full Copyright Statement
+
+   Copyright (C) The Internet Society (2000).  All Rights Reserved.
+
+   This document and translations of it may be copied and furnished to
+   others, and derivative works that comment on or otherwise explain it
+   or assist in its implementation may be prepared, copied, published
+   and distributed, in whole or in part, without restriction of any
+   kind, provided that the above copyright notice and this paragraph are
+   included on all such copies and derivative works.  However, this
+   document itself may not be modified in any way, such as by removing
+   the copyright notice or references to the Internet Society or other
+   Internet organizations, except as needed for the purpose of
+   developing Internet standards in which case the procedures for
+   copyrights defined in the Internet Standards process must be
+   followed, or as required to translate it into languages other than
+   English.
+
+   The limited permissions granted above are perpetual and will not be
+   revoked by the Internet Society or its successors or assigns.
+
+   This document and the information contained herein is provided on an
+   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
+   TASK FORCE DISCLAIMS 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.
+
+Acknowledgement
+
+   Funding for the RFC Editor function is currently provided by the
+   Internet Society.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Shirey                       Informational                    [Page 212]
+