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+Network Working Group                                          N. Haller
+Request for Comments: 1938                                      Bellcore
+Category: Standards Track                                        C. Metz
+                                              Kaman Sciences Corporation
+                                                                May 1996
+
+
+                       A One-Time Password System
+
+Status of this Memo
+
+   This document specifies an Internet standards track protocol for the
+   Internet community, and requests discussion and suggestions for
+   improvements.  Please refer to the current edition of the "Internet
+   Official Protocol Standards" (STD 1) for the standardization state
+   and status of this protocol.  Distribution of this memo is unlimited.
+
+1.0 ABSTRACT
+
+   This document describes a one-time password authentication system
+   (OTP). The system provides authentication for system access (login)
+   and other applications requiring authentication that is secure
+   against passive attacks based on replaying captured reusable
+   passwords. OTP evolved from the S/KEY (S/KEY is a trademark of
+   Bellcore) One-Time Password System that was released by Bellcore and
+   is described in references [3] and [5].
+
+2.0 OVERVIEW
+
+   One form of attack on networked computing systems is eavesdropping on
+   network connections to obtain authentication information such as the
+   login IDs and passwords of legitimate users. Once this information is
+   captured, it can be used at a later time to gain access to the
+   system. One-time password systems are designed to counter this type
+   of attack, called a "replay attack" [4].
+
+   The authentication system described in this document uses a secret
+   pass-phrase to generate a sequence of one-time (single use)
+   passwords.  With this system, the user's secret pass-phrase never
+   needs to cross the network at any time such as during authentication
+   or during pass-phrase changes. Thus, it is not vulnerable to replay
+   attacks.  Added security is provided by the property that no secret
+   information need be stored on any system, including the server being
+   protected.
+
+   The OTP system protects against external passive attacks against the
+   authentication subsystem. It does not prevent a network eavesdropper
+   from gaining access to private information and does not provide
+
+
+
+Haller & Metz               Standards Track                     [Page 1]
+
+RFC 1938               A One-Time Password System               May 1996
+
+
+   protection against either "social engineering" or active attacks [9].
+
+3.0 INTRODUCTION
+
+   There are two entities in the operation of the OTP one-time password
+   system. The generator must produce the appropriate one-time password
+   from the user's secret pass-phrase and from information provided in
+   the challenge from the server. The server must send a challenge that
+   includes the appropriate generation parameters to the generator, must
+   verify the one-time password received, must store the last valid
+   one-time password it received, and must store the corresponding one-
+   time password sequence number. The server must also facilitate the
+   changing of the user's secret pass-phrase in a secure manner.
+
+   The OTP system generator passes the user's secret pass-phrase, along
+   with a seed received from the server as part of the challenge,
+   through multiple iterations of a secure hash function to produce a
+   one-time password. After each successful authentication, the number
+   of secure hash function iterations is reduced by one.  Thus, a unique
+   sequence of passwords is generated.  The server verifies the one-time
+   password received from the generator by computing the secure hash
+   function once and comparing the result with the previously accepted
+   one-time password.  This technique was first suggested by Leslie
+   Lamport [1].
+
+4.0 REQUIREMENTS TERMINOLOGY
+
+   In this document, the words that are used to define the significance
+   of each particular requirement are usually capitalized.  These words
+   are:
+
+    - MUST
+
+      This word or the adjective "REQUIRED" means that the item is an
+      absolute requirement of the specification.
+
+    - SHOULD
+
+      This word or the adjective "RECOMMENDED" means that there might
+      exist valid reasons in particular circumstances to ignore this
+      item, but the full implications should be understood and the
+      case carefully weighed before taking a different course.
+
+    - MAY
+
+      This word or the adjective "OPTIONAL" means that this item is
+      truly optional.  One vendor might choose to include the item
+      because a particular marketplace requires it or because it
+
+
+
+Haller & Metz               Standards Track                     [Page 2]
+
+RFC 1938               A One-Time Password System               May 1996
+
+
+      enhances the product, for example; another vendor may omit the
+      same item.
+
+5.0 SECURE HASH FUNCTION
+
+   The security of the OTP system is based on the non-invertability of a
+   secure hash function. Such a function must be tractable to compute in
+   the forward direction, but computationally infeasible to invert.
+
+   The interfaces are currently defined for three such hash algorithms,
+   MD4 [2] and MD5 [6] by Ronald Rivest, and SHA [7] by NIST.  All
+   conforming implementations of both server and generators MUST support
+   MD5.  They SHOULD support SHA and MAY also support MD4.  Clearly, the
+   generator and server must use the same algorithm in order to
+   interoperate. Other hash algorithms may be specified for use with
+   this system by publishing the appropriate interfaces.
+
+   The secure hash algorithms listed above have the property that they
+   accept an input that is arbitrarily long and produce a fixed size
+   output. The OTP system folds this output to 64 bits using the
+   algorithms in the Appendix A. 64 bits is also the length of the one-
+   time passwords. This is believed to be long enough to be secure and
+   short enough to be entered manually (see below, Form of Output) when
+   necessary.
+
+6.0 GENERATION OF ONE-TIME PASSWORDS
+
+   This section describes the generation of the one-time passwords.
+   This process consists of an initial step in which all inputs are
+   combined, a computation step where the secure hash function is
+   applied a specified number of times, and an output function where the
+   64 bit one-time password is converted to a human readable form.
+
+   Initial Step
+
+      In principle, the user's secret pass-phrase may be of any length.
+      To reduce the risk from techniques such as exhaustive search or
+      dictionary attacks, character string pass-phrases MUST contain at
+      least 10 characters (see Form of Inputs below).  All
+      implementations MUST support a pass-phrases of at least 63
+      characters.  The secret pass-phrase is frequently, but is not
+      required to be, textual information provided by a user.
+
+      In this step, the pass phrase is concatenated with a seed that is
+      transmitted from the server in clear text. This non-secret seed
+      allows clients to use the same secret pass-phrase on multiple
+      machines (using different seeds) and to safely recycle their
+      secret pass-phrases by changing the seed.
+
+
+
+Haller & Metz               Standards Track                     [Page 3]
+
+RFC 1938               A One-Time Password System               May 1996
+
+
+      The result of the concatenation is passed through the secure hash
+      function and then is reduced to 64 bits using one of the function
+      dependent algorithms shown in Appendix A.
+
+   Computation Step
+
+      A sequence of one-time passwords is produced by applying the
+      secure hash function multiple times to the output of the initial
+      step (called S). That is, the first one-time password to be used
+      is produced by passing S through the secure hash function a number
+      of times (N) specified by the user. The next one-time password to
+      be used is generated by passing S though the secure hash function
+      N-1 times. An eavesdropper who has monitored the transmission of a
+      one- time password would not be able to generate the next required
+      password because doing so would mean inverting the hash function.
+
+   Form of Inputs
+
+      The secret pass-phrase is seen only by the OTP generator. To allow
+      interchangeability of generators, all generators MUST support a
+      secret pass-phrase of 10 to 63 characters. Implementations MAY
+      support a longer pass-phrase, but such implementations risk the
+      loss of interchangeability with implementations supporting only
+      the minimum.
+
+      The seed MUST consist of purely alphanumeric characters and MUST
+      be of one to 16 characters in length. The seed is a string of
+      characters that MUST not contain any blanks and SHOULD consist of
+      strictly alphanumeric characters from the ISO-646 Invariant Code
+      Set.  The seed MUST be case insensitive and MUST be internally
+      converted to lower case before it is processed.
+
+      The sequence number and seed together constitute a larger unit of
+      data called the challenge. The challenge gives the generator the
+      parameters it needs to calculate the correct one-time password
+      from the secret pass-phrase. The challenge MUST be in a standard
+      syntax so that automated generators can recognize the challenge in
+      context and extract these parameters. The syntax of the challenge
+      is:
+
+          otp-<algorithm identifier> <sequence integer> <seed>
+
+      The three tokens MUST be separated by a white space (defined as
+      any number of spaces and/or tabs) and the entire challenge string
+      MUST be terminated with either a space or a new line. The string
+      "otp-" MUST be in lower case.  The algorithm identifier is case
+      sensitive (the existing identifiers are all lower case), and the
+      seed is case insensitive and converted before use to lower case.
+
+
+
+Haller & Metz               Standards Track                     [Page 4]
+
+RFC 1938               A One-Time Password System               May 1996
+
+
+      If additional algorithms are defined, appropriate identifiers
+      (short, but not limited to three or four characters) must be
+      defined. The currently defined algorithm identifiers are:
+
+      md4        MD4 Message Digest
+      md5        MD5 Message Digest
+      sha1       NIST Secure Hash Algorithm Revision 1
+
+      An example of an OTP challenge is:   otp-md5 487 dog2
+
+   Form of Output
+
+      The one-time password generated by the above procedure is 64 bits
+      in length. Entering a 64 bit number is a difficult and error prone
+      process. Some generators insert this password into the input
+      stream and some others make it available for system "cut and
+      paste." Still other arrangements require the one-time password to
+      be entered manually. The OTP system is designed to facilitate this
+      manual entry without impeding automatic methods. The one-time
+      password therefore MAY be converted to, and all servers MUST be
+      capable of accepting it as, a sequence of six short (1 to 4
+      letter) easily typed words that only use characters from ISO-646
+      IVCS. Each word is chosen from a dictionary of 2048 words; at 11
+      bits per word, all one-time passwords may be encoded.
+
+      The two extra bits in this encoding are used to store a checksum.
+      The 64 bits of key are broken down into pairs of bits, then these
+      pairs are summed together. The two least significant bits of this
+      sum are encoded in the last two bits of the six word sequence with
+      the least significant bit of the sum as the last bit encoded. All
+      OTP generators MUST calculate this checksum and all OTP servers
+      MUST verify this checksum explicitly as part of the operation of
+      decoding this representation of the one-time password.
+
+      Generators that produce the six-word format MUST present the words
+      in upper case with single spaces used as separators. All servers
+      MUST accept six-word format without regard to case and white space
+      used as a separator. The two lines below represent the same one-
+      time password.  The first is valid as output from a generator and
+      as input a server, the second is valid only as human input to a
+      server.
+
+          OUST COAT FOAL MUG BEAK TOTE
+          oust coat foal  mug  beak  tote
+
+      Interoperability requires that all OTP servers and generators use
+      the same dictionary. The standard dictionary was originally
+      specified in the "S/KEY One Time Password System" that is
+
+
+
+Haller & Metz               Standards Track                     [Page 5]
+
+RFC 1938               A One-Time Password System               May 1996
+
+
+      described in RFC 1760 [5].  This dictionary is included in this
+      document as Appendix C.
+
+      To facilitate the implementation of smaller generators,
+      hexadecimal output is an acceptable alternative for the
+      presentation of the one-time password. All implementations of the
+      server software MUST accept case-insensitive hexadecimal as well
+      as six-word format. The hexadecimal digits may be separated by
+      white space so servers are REQUIRED to ignore all white space.  If
+      the representation is partitioned by white space, leading zeros
+      must be retained. Examples of hexadecimal format are:
+
+         Representation                Value
+
+         3503785b369cda8b              0x3503785b369cda8b
+         e5cc a1b8 7c13 096b           0xe5cca1b87c13096b
+         C7 48 90 F4 27 7B A1 CF       0xc74890f4277ba1cf
+         47 9 A68 28 4C 9D 0 1BC       0x479a68284c9d01bc
+
+      In addition to accepting six-word and hexadecimal encodings of the
+      64 bit one-time password, servers SHOULD accept the alternate
+      dictionary encoding described in Appendix B.  The six words in
+      this encoding MUST not overlap the set of words in the standard
+      dictionary.  To avoid ambiguity with the hexadecimal
+      representation, words in the alternate dictionary MUST not be
+      comprised solely of the letters A-F.  Decoding words thus encoded
+      does not require any knowledge of the alternative dictionary used
+      so the acceptance of any alternate dictionary implies the
+      acceptance of all alternate dictionaries.  Words in the
+      alternative dictionaries are case sensitive.  Generators and
+      servers MUST preserve the case in the processing of these words.
+
+      In summary, all conforming servers MUST accept six-word input that
+      uses the Standard Dictionary (RFC 1760 and Appendix C), MUST
+      accept hexadecimal encoding, and SHOULD accept six-word input that
+      uses the Alternative Dictionary technique (Appendix B).  As there
+      is a remote possibility that a hexadecimal encoding of a one-time
+      password will look like a valid six-word standard dictionary
+      encoding, all implementations MUST use the following scheme.  If a
+      six-word encoded one-time password is valid, it is accepted.
+      Otherwise, if the one-time password can be interpreted as
+      hexadecimal, and with that decoding it is valid, then it is
+      accepted.
+
+
+
+
+
+
+
+
+Haller & Metz               Standards Track                     [Page 6]
+
+RFC 1938               A One-Time Password System               May 1996
+
+
+7.0 VERIFICATION OF ONE-TIME PASSWORDS
+
+   An application on the server system that requires OTP authentication
+   is expected to issue an OTP challenge as described above. Given the
+   parameters from this challenge and the secret pass-phrase, the
+   generator can compute (or lookup) the one-time password that is
+   passed to the server to be verified.
+
+   The server system has a database containing, for each user, the one-
+   time password from the last successful authentication or the first
+   OTP of a newly initialized sequence. To authenticate the user, the
+   server decodes the one-time password received from the generator into
+   a 64-bit key and then runs this key through the secure hash function
+   once. If the result of this operation matches the stored previous
+   OTP, the authentication is successful and the accepted one-time
+   password is stored for future use.
+
+8.0 PASS-PHRASE CHANGES
+
+   Because the number of hash function applications executed by the
+   generator decreases by one each time, at some point the user must
+   reinitialize the system or be unable to authenticate.
+
+   Although some installations may not permit users to initialize
+   remotely, implementations MUST provide a means to do so that does not
+   reveal the user's secret pass-phrase.  One way is to provide a means
+   to reinitialize the  sequence through explicit specification of the
+   first one-time password.
+
+   When the sequence of one-time passwords is reinitialized,
+   implementations MUST verify that the seed or the pass-phrase is
+   changed.  Installations SHOULD discourage any operation that sends
+   the secret pass-phrase over a network in clear-text as such practice
+   defeats the concept of a one-time password.
+
+   Implementations MAY use the following technique for
+   [re]initialization:
+
+    o  The user picks a new seed and hash count (default values may
+       be offered).  The user provides these, along with the
+       corresponding generated one-time password, to the host system.
+
+    o  The user MAY also provide the corresponding generated one
+       time password for count-1 as an error check.
+
+    o  The user SHOULD provide the generated one-time password for
+       the old seed and old hash count to protect an idle terminal
+       or workstation (this implies that when the count is 1, the
+
+
+
+Haller & Metz               Standards Track                     [Page 7]
+
+RFC 1938               A One-Time Password System               May 1996
+
+
+       user can login but cannot then change the seed or count).
+
+   In the future a specific protocol may be defined for reinitialization
+   that will permit smooth and possibly automated interoperation of all
+   hosts and generators.
+
+9.0 PROTECTION AGAINST RACE ATTACK
+
+   All conforming server implementations MUST protect against the race
+   condition described in this section.  A defense against this attack
+   is outlined; implementations MAY use this approach or MAY select an
+   alternative defense.
+
+   It is possible for an attacker to listen to most of a one-time
+   password, guess the remainder, and then race the legitimate user to
+   complete the authentication.  Multiple guesses against the last word
+   of the six-word format are likely to succeed.
+
+   One possible defense is to prevent a user from starting multiple
+   simultaneous authentication sessions. This means that once the
+   legitimate user has initiated authentication, an attacker would be
+   blocked until the first authentication process has completed.  In
+   this approach, a timeout is necessary to thwart a denial of service
+   attack.
+
+10.0 SECURITY CONSIDERATIONS
+
+   This entire document discusses an authentication system that improves
+   security by limiting the danger of eavesdropping/replay attacks that
+   have been used against simple password systems [4].
+
+   The use of the OTP system only provides protections against passive
+   eavesdropping/replay attacks.  It does not provide for the privacy of
+   transmitted data, and it does not provide protection against active
+   attacks.  Active attacks against TCP connections are known to be
+   present in the current Internet [9].
+
+   The success of the OTP system to protect host systems is dependent on
+   the non-invertability of the secure hash functions used.  To our
+   knowledge, none of the hash algorithms have been broken, but it is
+   generally believed [6] that MD4 is not as strong as MD5.  If a server
+   supports multiple hash algorithms, it is only as secure as the
+   weakest algorithm.
+
+
+
+
+
+
+
+
+Haller & Metz               Standards Track                     [Page 8]
+
+RFC 1938               A One-Time Password System               May 1996
+
+
+11.0 ACKNOWLEDGMENTS
+
+   The idea behind OTP authentication was first proposed by Leslie
+   Lamport [1]. Bellcore's S/KEY system, from which OTP is derived, was
+   proposed by Phil Karn, who also wrote most of the Bellcore reference
+   implementation.
+
+12.0 REFERENCES
+
+  [1]  Leslie Lamport, "Password Authentication with Insecure
+       Communication", Communications of the ACM 24.11 (November
+       1981), 770-772
+
+  [2]  Rivest, R., "The MD4 Message-Digest Algorithm, RFC 1320",
+       MIT and RSA Data Security, Inc., April 1992.
+
+  [3]  Neil Haller, "The S/KEY One-Time Password System", Proceedings
+       of the ISOC Symposium on Network and Distributed System
+       Security, February 1994, San Diego, CA
+
+  [4]  Haller, N., and R. Atkinson, "On Internet Authentication",
+       RFC 1704, Bellcore and Naval Research Laboratory, October 1994.
+
+  [5]  Haller, N., "The S/KEY One-Time Password System", RFC 1760,
+       Bellcore, February 1995.
+
+  [6]  Rivest, R., "The MD5 Message-Digest Algorithm", RFC 1321,
+       MIT and RSA Data Security, Inc., April 1992.
+
+  [7]  National Institute of Standards and Technology (NIST),
+       "Announcing the Secure Hash Standard", FIPS 180-1, U.S.
+       Department of Commerce, April 1995.
+
+  [8]  International Standard - Information Processing -- ISO 7-bit
+       coded character set for information interchange (Invariant Code
+       Set), ISO-646, International Standards Organization, Geneva,
+       Switzerland, 1983
+
+  [9]  Computer Emergency Response Team (CERT), "IP Spoofing and
+       Hijacked Terminal Connections", CA-95:01, January 1995.
+       Available via anonymous ftp from info.cert.org in
+       /pub/cert_advisories.
+
+
+
+
+
+
+
+
+
+Haller & Metz               Standards Track                     [Page 9]
+
+RFC 1938               A One-Time Password System               May 1996
+
+
+13.0 AUTHORS' ADDRESSES
+
+   Neil Haller
+   Bellcore
+   MCC 1C-265B
+   445 South Street
+   Morristown, NJ, 07960-6438, USA
+
+   Phone: +1 201 829-4478
+   Fax:   +1 201 829-2504
+   EMail: nmh@bellcore.com
+
+
+   Craig Metz
+   Kaman Sciences Corporation
+   For NRL Code 5544
+   4555 Overlook Avenue, S.W.
+   Washington, DC, 20375-5337, USA
+
+   Phone: +1 202 404-7122
+   Fax:   +1 202 404-7942
+   EMail: cmetz@cs.nrl.navy.mil
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Haller & Metz               Standards Track                    [Page 10]
+
+RFC 1938               A One-Time Password System               May 1996
+
+
+Appendix A   -   Interfaces to Secure Hash Algorithms
+
+MD4 Message Digest (see reference [2])
+
+          strcpy(buf,seed);
+          strcat(buf,passwd);
+          MDbegin(&md)
+          MDupdate(&md,(unsigned char *)buf,8*buflen);
+
+          /* Fold result to 64 bits */
+          md.buffer[0] ^= md.buffer[2];
+          md.buffer[1] ^= md.buffer[3];
+
+
+MD5 Message Digest (see reference [6])
+
+          MD5_CTX mdCxt;
+
+          strcpy(buf,seed);
+          strcat(buf,passwd);
+
+          /* Crunch the key through MD5  */
+          MD5Init(&mdCxt);
+          MD5Update(&mdCxt,(unsigned char *)bits,strlen(bits));
+          MD5Update(&mdCxt,(unsigned char *)buf,buflen);
+          MD5Final(&mdCxt);
+
+          /* Fold result to 64 bits */
+          for( i = 0; i < 8; i++ )
+              result[i] = mdCxt.digest[i] ^ mdCxt.digest[i+8];
+
+
+SHA Secure Hash Algorithm (see reference [7])
+
+
+          /*  Fold 160 bit result to 64 bits */
+          md.buffer[0] ^= md.buffer[2];
+          md.buffer[1] ^= md.buffer[3];
+          md.buffer[0] ^= md.buffer[4];
+
+Appendix B   -   Alternative Dictionary Algorithm
+
+   The purpose of alternative dictionary encoding of the OTP one-time
+   password is to allow the use of language specific or friendly words.
+   As case translation is not always well defined, the alternative
+   dictionary encoding is case insensitive.  Servers SHOULD accept this
+   encoding in addition to the standard 6-word and hexadecimal
+   encodings.
+
+
+
+Haller & Metz               Standards Track                    [Page 11]
+
+RFC 1938               A One-Time Password System               May 1996
+
+
+GENERATOR ENCODING USING AN ALTERNATE DICTIONARY
+
+  The standard 6-word encoding uses the placement of a word in the
+  dictionary to represent an 11-bit number. The 64-bit one-time
+  password can then be represented by six words.
+
+  An alternative dictionary of 2048 words may be created such that
+  each word W and position of the word in the dictionary N obey the
+  relationship:
+
+          alg( W ) % 2048 == N
+  where
+          alg is the hash algorithm used (e.g. MD4, MD5, SHA1).
+
+  In addition, no words in the standard dictionary may be chosen.
+
+  The generator expands the 64-bit one-time password to 66 bits by
+  computing parity as with the standard 6-word encoding.  The six 11-
+  bit numbers are then converted to words using the dictionary that
+  was created such that the above relationship holds.
+
+
+SERVER DECODING OF ALTERNATE DICTIONARY ONE-TIME PASSWORDS
+
+  The server accepting alternative dictionary encoding converts each
+  word to an 11-bit number using the above encoding. These numbers are
+  then used in the same way as the decoded standard dictionary words
+  to form the 66-bit one-time password.
+
+  The server does not need to have access to the alternate dictionary
+  that was used to create the one-time password it is authenticating.
+  This is because the decoding from word to 11-bit number does not
+  make any use of the dictionary.  As a result of the independence of
+  the dictionary, a server accepting one alternate dictionary accept
+  all alternate dictionaries.
+
+Appendix C - Dictionary for Converting Between 6-Word and Binary
+Formats
+
+   This dictionary is from the module put.c in the original Bellcore
+   reference distribution.
+
+{        "A",    "ABE",   "ACE",   "ACT",   "AD",    "ADA",   "ADD",
+"AGO",   "AID",  "AIM",   "AIR",   "ALL",   "ALP",   "AM",    "AMY",
+"AN",    "ANA",  "AND",   "ANN",   "ANT",   "ANY",   "APE",   "APS",
+"APT",   "ARC",  "ARE",   "ARK",   "ARM",   "ART",   "AS",    "ASH",
+"ASK",   "AT",   "ATE",   "AUG",   "AUK",   "AVE",   "AWE",   "AWK",
+"AWL",   "AWN",  "AX",    "AYE",   "BAD",   "BAG",   "BAH",   "BAM",
+
+
+
+Haller & Metz               Standards Track                    [Page 12]
+
+RFC 1938               A One-Time Password System               May 1996
+
+
+"BAN",   "BAR",  "BAT",   "BAY",   "BE",    "BED",   "BEE",   "BEG",
+"BEN",   "BET",  "BEY",   "BIB",   "BID",   "BIG",   "BIN",   "BIT",
+"BOB",   "BOG",  "BON",   "BOO",   "BOP",   "BOW",   "BOY",   "BUB",
+"BUD",   "BUG",  "BUM",   "BUN",   "BUS",   "BUT",   "BUY",   "BY",
+"BYE",   "CAB",  "CAL",   "CAM",   "CAN",   "CAP",   "CAR",   "CAT",
+"CAW",   "COD",  "COG",   "COL",   "CON",   "COO",   "COP",   "COT",
+"COW",   "COY",  "CRY",   "CUB",   "CUE",   "CUP",   "CUR",   "CUT",
+"DAB",   "DAD",  "DAM",   "DAN",   "DAR",   "DAY",   "DEE",   "DEL",
+"DEN",   "DES",  "DEW",   "DID",   "DIE",   "DIG",   "DIN",   "DIP",
+"DO",    "DOE",  "DOG",   "DON",   "DOT",   "DOW",   "DRY",   "DUB",
+"DUD",   "DUE",  "DUG",   "DUN",   "EAR",   "EAT",   "ED",    "EEL",
+"EGG",   "EGO",  "ELI",   "ELK",   "ELM",   "ELY",   "EM",    "END",
+"EST",   "ETC",  "EVA",   "EVE",   "EWE",   "EYE",   "FAD",   "FAN",
+"FAR",   "FAT",  "FAY",   "FED",   "FEE",   "FEW",   "FIB",   "FIG",
+"FIN",   "FIR",  "FIT",   "FLO",   "FLY",   "FOE",   "FOG",   "FOR",
+"FRY",   "FUM",  "FUN",   "FUR",   "GAB",   "GAD",   "GAG",   "GAL",
+"GAM",   "GAP",  "GAS",   "GAY",   "GEE",   "GEL",   "GEM",   "GET",
+"GIG",   "GIL",  "GIN",   "GO",    "GOT",   "GUM",   "GUN",   "GUS",
+"GUT",   "GUY",  "GYM",   "GYP",   "HA",    "HAD",   "HAL",   "HAM",
+"HAN",   "HAP",  "HAS",   "HAT",   "HAW",   "HAY",   "HE",    "HEM",
+"HEN",   "HER",  "HEW",   "HEY",   "HI",    "HID",   "HIM",   "HIP",
+"HIS",   "HIT",  "HO",    "HOB",   "HOC",   "HOE",   "HOG",   "HOP",
+"HOT",   "HOW",  "HUB",   "HUE",   "HUG",   "HUH",   "HUM",   "HUT",
+"I",     "ICY",  "IDA",   "IF",    "IKE",   "ILL",   "INK",   "INN",
+"IO",    "ION",  "IQ",    "IRA",   "IRE",   "IRK",   "IS",    "IT",
+"ITS",   "IVY",  "JAB",   "JAG",   "JAM",   "JAN",   "JAR",   "JAW",
+"JAY",   "JET",  "JIG",   "JIM",   "JO",    "JOB",   "JOE",   "JOG",
+"JOT",   "JOY",  "JUG",   "JUT",   "KAY",   "KEG",   "KEN",   "KEY",
+"KID",   "KIM",  "KIN",   "KIT",   "LA",    "LAB",   "LAC",   "LAD",
+"LAG",   "LAM",  "LAP",   "LAW",   "LAY",   "LEA",   "LED",   "LEE",
+"LEG",   "LEN",  "LEO",   "LET",   "LEW",   "LID",   "LIE",   "LIN",
+"LIP",   "LIT",  "LO",    "LOB",   "LOG",   "LOP",   "LOS",   "LOT",
+"LOU",   "LOW",  "LOY",   "LUG",   "LYE",   "MA",    "MAC",   "MAD",
+"MAE",   "MAN",  "MAO",   "MAP",   "MAT",   "MAW",   "MAY",   "ME",
+"MEG",   "MEL",  "MEN",   "MET",   "MEW",   "MID",   "MIN",   "MIT",
+"MOB",   "MOD",  "MOE",   "MOO",   "MOP",   "MOS",   "MOT",   "MOW",
+"MUD",   "MUG",  "MUM",   "MY",    "NAB",   "NAG",   "NAN",   "NAP",
+"NAT",   "NAY",  "NE",    "NED",   "NEE",   "NET",   "NEW",   "NIB",
+"NIL",   "NIP",  "NIT",   "NO",    "NOB",   "NOD",   "NON",   "NOR",
+"NOT",   "NOV",  "NOW",   "NU",    "NUN",   "NUT",   "O",     "OAF",
+"OAK",   "OAR",  "OAT",   "ODD",   "ODE",   "OF",    "OFF",   "OFT",
+"OH",    "OIL",  "OK",    "OLD",   "ON",    "ONE",   "OR",    "ORB",
+"ORE",   "ORR",  "OS",    "OTT",   "OUR",   "OUT",   "OVA",   "OW",
+"OWE",   "OWL",  "OWN",   "OX",    "PA",    "PAD",   "PAL",   "PAM",
+"PAN",   "PAP",  "PAR",   "PAT",   "PAW",   "PAY",   "PEA",   "PEG",
+"PEN",   "PEP",  "PER",   "PET",   "PEW",   "PHI",   "PI",    "PIE",
+"PIN",   "PIT",  "PLY",   "PO",    "POD",   "POE",   "POP",   "POT",
+"POW",   "PRO",  "PRY",   "PUB",   "PUG",   "PUN",   "PUP",   "PUT",
+
+
+
+Haller & Metz               Standards Track                    [Page 13]
+
+RFC 1938               A One-Time Password System               May 1996
+
+
+"QUO",   "RAG",  "RAM",   "RAN",   "RAP",   "RAT",   "RAW",   "RAY",
+"REB",   "RED",  "REP",   "RET",   "RIB",   "RID",   "RIG",   "RIM",
+"RIO",   "RIP",  "ROB",   "ROD",   "ROE",   "RON",   "ROT",   "ROW",
+"ROY",   "RUB",  "RUE",   "RUG",   "RUM",   "RUN",   "RYE",   "SAC",
+"SAD",   "SAG",  "SAL",   "SAM",   "SAN",   "SAP",   "SAT",   "SAW",
+"SAY",   "SEA",  "SEC",   "SEE",   "SEN",   "SET",   "SEW",   "SHE",
+"SHY",   "SIN",  "SIP",   "SIR",   "SIS",   "SIT",   "SKI",   "SKY",
+"SLY",   "SO",   "SOB",   "SOD",   "SON",   "SOP",   "SOW",   "SOY",
+"SPA",   "SPY",  "SUB",   "SUD",   "SUE",   "SUM",   "SUN",   "SUP",
+"TAB",   "TAD",  "TAG",   "TAN",   "TAP",   "TAR",   "TEA",   "TED",
+"TEE",   "TEN",  "THE",   "THY",   "TIC",   "TIE",   "TIM",   "TIN",
+"TIP",   "TO",   "TOE",   "TOG",   "TOM",   "TON",   "TOO",   "TOP",
+"TOW",   "TOY",  "TRY",   "TUB",   "TUG",   "TUM",   "TUN",   "TWO",
+"UN",    "UP",   "US",    "USE",   "VAN",   "VAT",   "VET",   "VIE",
+"WAD",   "WAG",  "WAR",   "WAS",   "WAY",   "WE",    "WEB",   "WED",
+"WEE",   "WET",  "WHO",   "WHY",   "WIN",   "WIT",   "WOK",   "WON",
+"WOO",   "WOW",  "WRY",   "WU",    "YAM",   "YAP",   "YAW",   "YE",
+"YEA",   "YES",  "YET",   "YOU",   "ABED",  "ABEL",  "ABET",  "ABLE",
+"ABUT",  "ACHE",  "ACID", "ACME",  "ACRE",  "ACTA",  "ACTS",  "ADAM",
+"ADDS",  "ADEN",  "AFAR", "AFRO",  "AGEE",  "AHEM",  "AHOY",  "AIDA",
+"AIDE",  "AIDS",  "AIRY", "AJAR",  "AKIN",  "ALAN",  "ALEC",  "ALGA",
+"ALIA",  "ALLY",  "ALMA", "ALOE",  "ALSO",  "ALTO",  "ALUM",  "ALVA",
+"AMEN",  "AMES",  "AMID", "AMMO",  "AMOK",  "AMOS",  "AMRA",  "ANDY",
+"ANEW",  "ANNA",  "ANNE", "ANTE",  "ANTI",  "AQUA",  "ARAB",  "ARCH",
+"AREA",  "ARGO",  "ARID", "ARMY",  "ARTS",  "ARTY",  "ASIA",  "ASKS",
+"ATOM",  "AUNT",  "AURA", "AUTO",  "AVER",  "AVID",  "AVIS",  "AVON",
+"AVOW",  "AWAY",  "AWRY", "BABE",  "BABY",  "BACH",  "BACK",  "BADE",
+"BAIL",  "BAIT",  "BAKE", "BALD",  "BALE",  "BALI",  "BALK",  "BALL",
+"BALM",  "BAND",  "BANE", "BANG",  "BANK",  "BARB",  "BARD",  "BARE",
+"BARK",  "BARN",  "BARR", "BASE",  "BASH",  "BASK",  "BASS",  "BATE",
+"BATH",  "BAWD",  "BAWL", "BEAD",  "BEAK",  "BEAM",  "BEAN",  "BEAR",
+"BEAT",  "BEAU",  "BECK", "BEEF",  "BEEN",  "BEER",  "BEET",  "BELA",
+"BELL",  "BELT",  "BEND", "BENT",  "BERG",  "BERN",  "BERT",  "BESS",
+"BEST",  "BETA",  "BETH", "BHOY",  "BIAS",  "BIDE",  "BIEN",  "BILE",
+"BILK",  "BILL",  "BIND", "BING",  "BIRD",  "BITE",  "BITS",  "BLAB",
+"BLAT",  "BLED",  "BLEW", "BLOB",  "BLOC",  "BLOT",  "BLOW",  "BLUE",
+"BLUM",  "BLUR",  "BOAR", "BOAT",  "BOCA",  "BOCK",  "BODE",  "BODY",
+"BOGY",  "BOHR",  "BOIL", "BOLD",  "BOLO",  "BOLT",  "BOMB",  "BONA",
+"BOND",  "BONE",  "BONG", "BONN",  "BONY",  "BOOK",  "BOOM",  "BOON",
+"BOOT",  "BORE",  "BORG", "BORN",  "BOSE",  "BOSS",  "BOTH",  "BOUT",
+"BOWL",  "BOYD",  "BRAD", "BRAE",  "BRAG",  "BRAN",  "BRAY",  "BRED",
+"BREW",  "BRIG",  "BRIM", "BROW",  "BUCK",  "BUDD",  "BUFF",  "BULB",
+"BULK",  "BULL",  "BUNK", "BUNT",  "BUOY",  "BURG",  "BURL",  "BURN",
+"BURR",  "BURT",  "BURY", "BUSH",  "BUSS",  "BUST",  "BUSY",  "BYTE",
+"CADY",  "CAFE",  "CAGE", "CAIN",  "CAKE",  "CALF",  "CALL",  "CALM",
+"CAME",  "CANE",  "CANT", "CARD",  "CARE",  "CARL",  "CARR",  "CART",
+"CASE",  "CASH",  "CASK", "CAST",  "CAVE",  "CEIL",  "CELL",  "CENT",
+"CERN",  "CHAD",  "CHAR", "CHAT",  "CHAW",  "CHEF",  "CHEN",  "CHEW",
+
+
+
+Haller & Metz               Standards Track                    [Page 14]
+
+RFC 1938               A One-Time Password System               May 1996
+
+
+"CHIC",  "CHIN",  "CHOU", "CHOW",  "CHUB",  "CHUG",  "CHUM",  "CITE",
+"CITY",  "CLAD",  "CLAM", "CLAN",  "CLAW",  "CLAY",  "CLOD",  "CLOG",
+"CLOT",  "CLUB",  "CLUE", "COAL",  "COAT",  "COCA",  "COCK",  "COCO",
+"CODA",  "CODE",  "CODY", "COED",  "COIL",  "COIN",  "COKE",  "COLA",
+"COLD",  "COLT",  "COMA", "COMB",  "COME",  "COOK",  "COOL",  "COON",
+"COOT",  "CORD",  "CORE", "CORK",  "CORN",  "COST",  "COVE",  "COWL",
+"CRAB",  "CRAG",  "CRAM", "CRAY",  "CREW",  "CRIB",  "CROW",  "CRUD",
+"CUBA",  "CUBE",  "CUFF", "CULL",  "CULT",  "CUNY",  "CURB",  "CURD",
+"CURE",  "CURL",  "CURT", "CUTS",  "DADE",  "DALE",  "DAME",  "DANA",
+"DANE",  "DANG",  "DANK", "DARE",  "DARK",  "DARN",  "DART",  "DASH",
+"DATA",  "DATE",  "DAVE", "DAVY",  "DAWN",  "DAYS",  "DEAD",  "DEAF",
+"DEAL",  "DEAN",  "DEAR", "DEBT",  "DECK",  "DEED",  "DEEM",  "DEER",
+"DEFT",  "DEFY",  "DELL", "DENT",  "DENY",  "DESK",  "DIAL",  "DICE",
+"DIED",  "DIET",  "DIME", "DINE",  "DING",  "DINT",  "DIRE",  "DIRT",
+"DISC",  "DISH",  "DISK", "DIVE",  "DOCK",  "DOES",  "DOLE",  "DOLL",
+"DOLT",  "DOME",  "DONE", "DOOM",  "DOOR",  "DORA",  "DOSE",  "DOTE",
+"DOUG",  "DOUR",  "DOVE", "DOWN",  "DRAB",  "DRAG",  "DRAM",  "DRAW",
+"DREW",  "DRUB",  "DRUG", "DRUM",  "DUAL",  "DUCK",  "DUCT",  "DUEL",
+"DUET",  "DUKE",  "DULL", "DUMB",  "DUNE",  "DUNK",  "DUSK",  "DUST",
+"DUTY",  "EACH",  "EARL", "EARN",  "EASE",  "EAST",  "EASY",  "EBEN",
+"ECHO",  "EDDY",  "EDEN", "EDGE",  "EDGY",  "EDIT",  "EDNA",  "EGAN",
+"ELAN",  "ELBA",  "ELLA", "ELSE",  "EMIL",  "EMIT",  "EMMA",  "ENDS",
+"ERIC",  "EROS",  "EVEN", "EVER",  "EVIL",  "EYED",  "FACE",  "FACT",
+"FADE",  "FAIL",  "FAIN", "FAIR",  "FAKE",  "FALL",  "FAME",  "FANG",
+"FARM",  "FAST",  "FATE", "FAWN",  "FEAR",  "FEAT",  "FEED",  "FEEL",
+"FEET",  "FELL",  "FELT", "FEND",  "FERN",  "FEST",  "FEUD",  "FIEF",
+"FIGS",  "FILE",  "FILL", "FILM",  "FIND",  "FINE",  "FINK",  "FIRE",
+"FIRM",  "FISH",  "FISK", "FIST",  "FITS",  "FIVE",  "FLAG",  "FLAK",
+"FLAM",  "FLAT",  "FLAW", "FLEA",  "FLED",  "FLEW",  "FLIT",  "FLOC",
+"FLOG",  "FLOW",  "FLUB", "FLUE",  "FOAL",  "FOAM",  "FOGY",  "FOIL",
+"FOLD",  "FOLK",  "FOND", "FONT",  "FOOD",  "FOOL",  "FOOT",  "FORD",
+"FORE",  "FORK",  "FORM", "FORT",  "FOSS",  "FOUL",  "FOUR",  "FOWL",
+"FRAU",  "FRAY",  "FRED", "FREE",  "FRET",  "FREY",  "FROG",  "FROM",
+"FUEL",  "FULL",  "FUME", "FUND",  "FUNK",  "FURY",  "FUSE",  "FUSS",
+"GAFF",  "GAGE",  "GAIL", "GAIN",  "GAIT",  "GALA",  "GALE",  "GALL",
+"GALT",  "GAME",  "GANG", "GARB",  "GARY",  "GASH",  "GATE",  "GAUL",
+"GAUR",  "GAVE",  "GAWK", "GEAR",  "GELD",  "GENE",  "GENT",  "GERM",
+"GETS",  "GIBE",  "GIFT", "GILD",  "GILL",  "GILT",  "GINA",  "GIRD",
+"GIRL",  "GIST",  "GIVE", "GLAD",  "GLEE",  "GLEN",  "GLIB",  "GLOB",
+"GLOM",  "GLOW",  "GLUE", "GLUM",  "GLUT",  "GOAD",  "GOAL",  "GOAT",
+"GOER",  "GOES",  "GOLD", "GOLF",  "GONE",  "GONG",  "GOOD",  "GOOF",
+"GORE",  "GORY",  "GOSH", "GOUT",  "GOWN",  "GRAB",  "GRAD",  "GRAY",
+"GREG",  "GREW",  "GREY", "GRID",  "GRIM",  "GRIN",  "GRIT",  "GROW",
+"GRUB",  "GULF",  "GULL", "GUNK",  "GURU",  "GUSH",  "GUST",  "GWEN",
+"GWYN",  "HAAG",  "HAAS", "HACK",  "HAIL",  "HAIR",  "HALE",  "HALF",
+"HALL",  "HALO",  "HALT", "HAND",  "HANG",  "HANK",  "HANS",  "HARD",
+"HARK",  "HARM",  "HART", "HASH",  "HAST",  "HATE",  "HATH",  "HAUL",
+"HAVE",  "HAWK",  "HAYS", "HEAD",  "HEAL",  "HEAR",  "HEAT",  "HEBE",
+
+
+
+Haller & Metz               Standards Track                    [Page 15]
+
+RFC 1938               A One-Time Password System               May 1996
+
+
+"HECK",  "HEED",  "HEEL", "HEFT",  "HELD",  "HELL",  "HELM",  "HERB",
+"HERD",  "HERE",  "HERO", "HERS",  "HESS",  "HEWN",  "HICK",  "HIDE",
+"HIGH",  "HIKE",  "HILL", "HILT",  "HIND",  "HINT",  "HIRE",  "HISS",
+"HIVE",  "HOBO",  "HOCK", "HOFF",  "HOLD",  "HOLE",  "HOLM",  "HOLT",
+"HOME",  "HONE",  "HONK", "HOOD",  "HOOF",  "HOOK",  "HOOT",  "HORN",
+"HOSE",  "HOST",  "HOUR", "HOVE",  "HOWE",  "HOWL",  "HOYT",  "HUCK",
+"HUED",  "HUFF",  "HUGE", "HUGH",  "HUGO",  "HULK",  "HULL",  "HUNK",
+"HUNT",  "HURD",  "HURL", "HURT",  "HUSH",  "HYDE",  "HYMN",  "IBIS",
+"ICON",  "IDEA",  "IDLE", "IFFY",  "INCA",  "INCH",  "INTO",  "IONS",
+"IOTA",  "IOWA",  "IRIS", "IRMA",  "IRON",  "ISLE",  "ITCH",  "ITEM",
+"IVAN",  "JACK",  "JADE", "JAIL",  "JAKE",  "JANE",  "JAVA",  "JEAN",
+"JEFF",  "JERK",  "JESS", "JEST",  "JIBE",  "JILL",  "JILT",  "JIVE",
+"JOAN",  "JOBS",  "JOCK", "JOEL",  "JOEY",  "JOHN",  "JOIN",  "JOKE",
+"JOLT",  "JOVE",  "JUDD", "JUDE",  "JUDO",  "JUDY",  "JUJU",  "JUKE",
+"JULY",  "JUNE",  "JUNK", "JUNO",  "JURY",  "JUST",  "JUTE",  "KAHN",
+"KALE",  "KANE",  "KANT", "KARL",  "KATE",  "KEEL",  "KEEN",  "KENO",
+"KENT",  "KERN",  "KERR", "KEYS",  "KICK",  "KILL",  "KIND",  "KING",
+"KIRK",  "KISS",  "KITE", "KLAN",  "KNEE",  "KNEW",  "KNIT",  "KNOB",
+"KNOT",  "KNOW",  "KOCH", "KONG",  "KUDO",  "KURD",  "KURT",  "KYLE",
+"LACE",  "LACK",  "LACY", "LADY",  "LAID",  "LAIN",  "LAIR",  "LAKE",
+"LAMB",  "LAME",  "LAND", "LANE",  "LANG",  "LARD",  "LARK",  "LASS",
+"LAST",  "LATE",  "LAUD", "LAVA",  "LAWN",  "LAWS",  "LAYS",  "LEAD",
+"LEAF",  "LEAK",  "LEAN", "LEAR",  "LEEK",  "LEER",  "LEFT",  "LEND",
+"LENS",  "LENT",  "LEON", "LESK",  "LESS",  "LEST",  "LETS",  "LIAR",
+"LICE",  "LICK",  "LIED", "LIEN",  "LIES",  "LIEU",  "LIFE",  "LIFT",
+"LIKE",  "LILA",  "LILT", "LILY",  "LIMA",  "LIMB",  "LIME",  "LIND",
+"LINE",  "LINK",  "LINT", "LION",  "LISA",  "LIST",  "LIVE",  "LOAD",
+"LOAF",  "LOAM",  "LOAN", "LOCK",  "LOFT",  "LOGE",  "LOIS",  "LOLA",
+"LONE",  "LONG",  "LOOK", "LOON",  "LOOT",  "LORD",  "LORE",  "LOSE",
+"LOSS",  "LOST",  "LOUD", "LOVE",  "LOWE",  "LUCK",  "LUCY",  "LUGE",
+"LUKE",  "LULU",  "LUND", "LUNG",  "LURA",  "LURE",  "LURK",  "LUSH",
+"LUST",  "LYLE",  "LYNN", "LYON",  "LYRA",  "MACE",  "MADE",  "MAGI",
+"MAID",  "MAIL",  "MAIN", "MAKE",  "MALE",  "MALI",  "MALL",  "MALT",
+"MANA",  "MANN",  "MANY", "MARC",  "MARE",  "MARK",  "MARS",  "MART",
+"MARY",  "MASH",  "MASK", "MASS",  "MAST",  "MATE",  "MATH",  "MAUL",
+"MAYO",  "MEAD",  "MEAL", "MEAN",  "MEAT",  "MEEK",  "MEET",  "MELD",
+"MELT",  "MEMO",  "MEND", "MENU",  "MERT",  "MESH",  "MESS",  "MICE",
+"MIKE",  "MILD",  "MILE", "MILK",  "MILL",  "MILT",  "MIMI",  "MIND",
+"MINE",  "MINI",  "MINK", "MINT",  "MIRE",  "MISS",  "MIST",  "MITE",
+"MITT",  "MOAN",  "MOAT", "MOCK",  "MODE",  "MOLD",  "MOLE",  "MOLL",
+"MOLT",  "MONA",  "MONK", "MONT",  "MOOD",  "MOON",  "MOOR",  "MOOT",
+"MORE",  "MORN",  "MORT", "MOSS",  "MOST",  "MOTH",  "MOVE",  "MUCH",
+"MUCK",  "MUDD",  "MUFF", "MULE",  "MULL",  "MURK",  "MUSH",  "MUST",
+"MUTE",  "MUTT",  "MYRA", "MYTH",  "NAGY",  "NAIL",  "NAIR",  "NAME",
+"NARY",  "NASH",  "NAVE", "NAVY",  "NEAL",  "NEAR",  "NEAT",  "NECK",
+"NEED",  "NEIL",  "NELL", "NEON",  "NERO",  "NESS",  "NEST",  "NEWS",
+"NEWT",  "NIBS",  "NICE", "NICK",  "NILE",  "NINA",  "NINE",  "NOAH",
+"NODE",  "NOEL",  "NOLL", "NONE",  "NOOK",  "NOON",  "NORM",  "NOSE",
+
+
+
+Haller & Metz               Standards Track                    [Page 16]
+
+RFC 1938               A One-Time Password System               May 1996
+
+
+"NOTE",  "NOUN",  "NOVA", "NUDE",  "NULL",  "NUMB",  "OATH",  "OBEY",
+"OBOE",  "ODIN",  "OHIO", "OILY",  "OINT",  "OKAY",  "OLAF",  "OLDY",
+"OLGA",  "OLIN",  "OMAN", "OMEN",  "OMIT",  "ONCE",  "ONES",  "ONLY",
+"ONTO",  "ONUS",  "ORAL", "ORGY",  "OSLO",  "OTIS",  "OTTO",  "OUCH",
+"OUST",  "OUTS",  "OVAL", "OVEN",  "OVER",  "OWLY",  "OWNS",  "QUAD",
+"QUIT",  "QUOD",  "RACE", "RACK",  "RACY",  "RAFT",  "RAGE",  "RAID",
+"RAIL",  "RAIN",  "RAKE", "RANK",  "RANT",  "RARE",  "RASH",  "RATE",
+"RAVE",  "RAYS",  "READ", "REAL",  "REAM",  "REAR",  "RECK",  "REED",
+"REEF",  "REEK",  "REEL", "REID",  "REIN",  "RENA",  "REND",  "RENT",
+"REST",  "RICE",  "RICH", "RICK",  "RIDE",  "RIFT",  "RILL",  "RIME",
+"RING",  "RINK",  "RISE", "RISK",  "RITE",  "ROAD",  "ROAM",  "ROAR",
+"ROBE",  "ROCK",  "RODE", "ROIL",  "ROLL",  "ROME",  "ROOD",  "ROOF",
+"ROOK",  "ROOM",  "ROOT", "ROSA",  "ROSE",  "ROSS",  "ROSY",  "ROTH",
+"ROUT",  "ROVE",  "ROWE", "ROWS",  "RUBE",  "RUBY",  "RUDE",  "RUDY",
+"RUIN",  "RULE",  "RUNG", "RUNS",  "RUNT",  "RUSE",  "RUSH",  "RUSK",
+"RUSS",  "RUST",  "RUTH", "SACK",  "SAFE",  "SAGE",  "SAID",  "SAIL",
+"SALE",  "SALK",  "SALT", "SAME",  "SAND",  "SANE",  "SANG",  "SANK",
+"SARA",  "SAUL",  "SAVE", "SAYS",  "SCAN",  "SCAR",  "SCAT",  "SCOT",
+"SEAL",  "SEAM",  "SEAR", "SEAT",  "SEED",  "SEEK",  "SEEM",  "SEEN",
+"SEES",  "SELF",  "SELL", "SEND",  "SENT",  "SETS",  "SEWN",  "SHAG",
+"SHAM",  "SHAW",  "SHAY", "SHED",  "SHIM",  "SHIN",  "SHOD",  "SHOE",
+"SHOT",  "SHOW",  "SHUN", "SHUT",  "SICK",  "SIDE",  "SIFT",  "SIGH",
+"SIGN",  "SILK",  "SILL", "SILO",  "SILT",  "SINE",  "SING",  "SINK",
+"SIRE",  "SITE",  "SITS", "SITU",  "SKAT",  "SKEW",  "SKID",  "SKIM",
+"SKIN",  "SKIT",  "SLAB", "SLAM",  "SLAT",  "SLAY",  "SLED",  "SLEW",
+"SLID",  "SLIM",  "SLIT", "SLOB",  "SLOG",  "SLOT",  "SLOW",  "SLUG",
+"SLUM",  "SLUR",  "SMOG", "SMUG",  "SNAG",  "SNOB",  "SNOW",  "SNUB",
+"SNUG",  "SOAK",  "SOAR", "SOCK",  "SODA",  "SOFA",  "SOFT",  "SOIL",
+"SOLD",  "SOME",  "SONG", "SOON",  "SOOT",  "SORE",  "SORT",  "SOUL",
+"SOUR",  "SOWN",  "STAB", "STAG",  "STAN",  "STAR",  "STAY",  "STEM",
+"STEW",  "STIR",  "STOW", "STUB",  "STUN",  "SUCH",  "SUDS",  "SUIT",
+"SULK",  "SUMS",  "SUNG", "SUNK",  "SURE",  "SURF",  "SWAB",  "SWAG",
+"SWAM",  "SWAN",  "SWAT", "SWAY",  "SWIM",  "SWUM",  "TACK",  "TACT",
+"TAIL",  "TAKE",  "TALE", "TALK",  "TALL",  "TANK",  "TASK",  "TATE",
+"TAUT",  "TEAL",  "TEAM", "TEAR",  "TECH",  "TEEM",  "TEEN",  "TEET",
+"TELL",  "TEND",  "TENT", "TERM",  "TERN",  "TESS",  "TEST",  "THAN",
+"THAT",  "THEE",  "THEM", "THEN",  "THEY",  "THIN",  "THIS",  "THUD",
+"THUG",  "TICK",  "TIDE", "TIDY",  "TIED",  "TIER",  "TILE",  "TILL",
+"TILT",  "TIME",  "TINA", "TINE",  "TINT",  "TINY",  "TIRE",  "TOAD",
+"TOGO",  "TOIL",  "TOLD", "TOLL",  "TONE",  "TONG",  "TONY",  "TOOK",
+"TOOL",  "TOOT",  "TORE", "TORN",  "TOTE",  "TOUR",  "TOUT",  "TOWN",
+"TRAG",  "TRAM",  "TRAY", "TREE",  "TREK",  "TRIG",  "TRIM",  "TRIO",
+"TROD",  "TROT",  "TROY", "TRUE",  "TUBA",  "TUBE",  "TUCK",  "TUFT",
+"TUNA",  "TUNE",  "TUNG", "TURF",  "TURN",  "TUSK",  "TWIG",  "TWIN",
+"TWIT",  "ULAN",  "UNIT", "URGE",  "USED",  "USER",  "USES",  "UTAH",
+"VAIL",  "VAIN",  "VALE", "VARY",  "VASE",  "VAST",  "VEAL",  "VEDA",
+"VEIL",  "VEIN",  "VEND", "VENT",  "VERB",  "VERY",  "VETO",  "VICE",
+"VIEW",  "VINE",  "VISE", "VOID",  "VOLT",  "VOTE",  "WACK",  "WADE",
+
+
+
+Haller & Metz               Standards Track                    [Page 17]
+
+RFC 1938               A One-Time Password System               May 1996
+
+
+"WAGE",  "WAIL",  "WAIT", "WAKE",  "WALE",  "WALK",  "WALL",  "WALT",
+"WAND",  "WANE",  "WANG", "WANT",  "WARD",  "WARM",  "WARN",  "WART",
+"WASH",  "WAST",  "WATS", "WATT",  "WAVE",  "WAVY",  "WAYS",  "WEAK",
+"WEAL",  "WEAN",  "WEAR", "WEED",  "WEEK",  "WEIR",  "WELD",  "WELL",
+"WELT",  "WENT",  "WERE", "WERT",  "WEST",  "WHAM",  "WHAT",  "WHEE",
+"WHEN",  "WHET",  "WHOA", "WHOM",  "WICK",  "WIFE",  "WILD",  "WILL",
+"WIND",  "WINE",  "WING", "WINK",  "WINO",  "WIRE",  "WISE",  "WISH",
+"WITH",  "WOLF",  "WONT", "WOOD",  "WOOL",  "WORD",  "WORE",  "WORK",
+"WORM",  "WORN",  "WOVE", "WRIT",  "WYNN",  "YALE",  "YANG",  "YANK",
+"YARD",  "YARN",  "YAWL", "YAWN",  "YEAH",  "YEAR",  "YELL",  "YOGA",
+"YOKE"                         };
+
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+Haller & Metz               Standards Track                    [Page 18]
+