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INTERNET DRAFT                                             Neil Haller
draft-haller-otp-04.txt                                       Bellcore
October 23, 1995                                            Craig Metz
                                            Kaman Sciences Corporation


                      A One-Time Password System


STATUS OF THIS MEMO

  This document is an Internet Draft. Internet Drafts are working
  documents of the Internet Engineering Task Force (IETF), its Areas
  and Working Groups. Note that other groups may also distribute
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  munnari.oz.au (Pacific Rim).

  The distribution of this Internet Draft is unlimited. It is filed as
  <draft-haller-otp-04.txt> and it expires on April 23, 1996.

1.0 ABSTRACT

  This document describes a one-time password authentication system
  (OTP). The OTP 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* 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 computing system. One-time password systems are
  designed to counter this type of attack, called a "replay attack"
  [4].


---------
 *   S/KEY is a trademark of Bellcore



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  The authentication system described in this document uses a secret
  pass-phase to generate a sequence of single use (one-time)
  passwords.  With this system, the user's secret pass-phrase never
  crosses 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
  protection against either "social engineering" or against active
  attacks where the potential intruder is able to intercept and modify
  the packet stream [9].

3.0 INTRODUCTION

  There are two entities in the operation of the OTP one-time password
  system. The client must generate 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 client, 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. On each use, 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 client 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.





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    - 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
      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 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


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  MUST support a pass-phrase with a maximum of at least a 63 pass-
  phrase. 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 a client to use the same secret pass-phrase on multiple
  machines (using different seeds) and to safely recycle secret
  passwords by changing the seed.

  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.

  To achieve a uniform minimum pass-phrase complexity, all generators
  MUST enforce the following rules for character-string pass-phrases:
  Pass-phrases MUST be at least 10 characters in length, MUST contain
  at least one upper case alphabetic, MUST contain at least one lower
  case alphabetic, and MUST contain at least one non-blank non-
  alphabetic.

  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


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  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 blanks 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.  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

    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
    accept 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-


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    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 at 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
    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.
    Examples of hexadecimal format are:

              3503785b369cda8b
              e5cc a1b8 7c13 096b
              C7 48 90 F4 27 7B A1 CF

  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.

  In summary, all conforming servers MUST accept six-word input that
  uses the Standard Dictionary (RFC 1760), 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 an 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.

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


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  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 client
  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
  client decreases by one each time, at some point the user must
  reinitialize the system or be unable to authenticate.

  Implementations MUST provide clients with a means of reinitializing
  a sequence through explicit specification of the first one-time
  password of a sequence. This allows a client to initialize without
  making it necessary to send a secret pass-phrase over the network as
  only the one-time password is sent. When the sequence of one-time
  passwords is reinitialized, implementations MUST verify that the
  seed is changed. Installations SHOULD discourage any operation that
  sends the secret pass-phrase over a network 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
       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


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  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.

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]  R. L. Rivest, The MD4 Message-Digest Algorithm, "Request For
       Comments (RFC) 1320", MIT and RSA Data Security, Inc., April
       1992


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  [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]  Neil Haller & Ran Atkinson, On Internet Authentication,
       "Request for Comments (RFC) 1704", Bellcore and Naval Research
       Laboratory, October 1994

  [5]  Neil Haller, The S/KEY One-Time Password System, "Request for
       Comments (RFC) 1760", Bellcore, February 1995

  [6]  R. L. Rivest, The MD5 Message-Digest Algorithm, "Request For
       Comments (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.


13.0 AUTHOR'S ADDRESS

  Neil Haller
  Bellcore
  MRE 2Q-280
  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


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  Email: cmetz@cs.nrl.navy.mil




















































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        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];













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          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.
Servers SHOULD accept this encoding in addition to the standard 6-word
and hexadecimal encodings.


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( uppercase( W ) ) % 2048 == N
  where
          alg is the hash algorithm used (e.g. MD4, MD5, SHA).

  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.









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Appendix C   -   Dictionary for Converting Between 6-Word and Binary Formats


This dictionary is from the module put.c.


{           "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",
"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",


Haller & Metz                                                [Page 13]


INTERNET DRAFT        A One Time Password System      October 23, 1995


"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",
"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",


Haller & Metz                                                [Page 14]


INTERNET DRAFT        A One Time Password System      October 23, 1995


"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",
"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",


Haller & Metz                                                [Page 15]


INTERNET DRAFT        A One Time Password System      October 23, 1995


"HALL",  "HALO",  "HALT",  "HAND",  "HANG",  "HANK",  "HANS",  "HARD",
"HARK",  "HARM",  "HART",  "HASH",  "HAST",  "HATE",  "HATH",  "HAUL",
"HAVE",  "HAWK",  "HAYS",  "HEAD",  "HEAL",  "HEAR",  "HEAT",  "HEBE",
"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                                                [Page 16]


INTERNET DRAFT        A One Time Password System      October 23, 1995


"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",
"WAGE",  "WAIL",  "WAIT",  "WAKE",  "WALE",  "WALK",  "WALL",  "WALT",
"WAND",  "WANE",  "WANG",  "WANT",  "WARD",  "WARM",  "WARN",  "WART",
"WASH",  "WAST",  "WATS",  "WATT",  "WAVE",  "WAVY",  "WAYS",  "WEAK",


Haller & Metz                                                [Page 17]


INTERNET DRAFT        A One Time Password System      October 23, 1995


"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"      };













































Haller & Metz                                                [Page 18]


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