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Network Working Group N. Haller Request for Comments: 2289 Bellcore Obsoletes: 1938 C. Metz Category: Standards Track Kaman Sciences Corporation

                                                           P. Nesser
                                          Nesser & Nesser Consulting
                                                            M. Straw
                                                            Bellcore
                                                       February 1998
                     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.

Copyright Notice

 Copyright (C) The Internet Society (1998).  All Rights Reserved.

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

Haller Standards Track [Page 1] RFC 2289 A One-Time Password System February 1998

 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 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:
  1. MUST
     This word or the adjective "REQUIRED" means that the item is an
     absolute requirement of the specification.

Haller Standards Track [Page 2] RFC 2289 A One-Time Password System February 1998

  1. 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.
  1. 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 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.
 Appendix C contains examples of the outputs given a collection of
 inputs.  It provides implementors with a means of verification the
 use of these algorithms.

Haller Standards Track [Page 3] RFC 2289 A One-Time Password System February 1998

 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.
 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.

Haller Standards Track [Page 4] RFC 2289 A One-Time Password System February 1998

 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.  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.

Haller Standards Track [Page 5] RFC 2289 A One-Time Password System February 1998

 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 described
   in RFC 1760 [5].  This dictionary is included in this document as
   Appendix D.
   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 D), MUST accept
 hexadecimal encoding, and SHOULD accept six-word input that uses the

Haller Standards Track [Page 6] RFC 2289 A One-Time Password System February 1998

 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.

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:

Haller Standards Track [Page 7] RFC 2289 A One-Time Password System February 1998

    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
 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 such as session hijacking that are known to be
 present in the current Internet [9].  The use of IP Security
 (IPsec), see [10], [11], and [12] is recommended to protect against
 TCP session hijacking.

Haller Standards Track [Page 8] RFC 2289 A One-Time Password System February 1998

 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]  Rivest, R., "The MD4 Message-Digest Algorithm", RFC 1320,
      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, October 1994.
 [5]  Haller, N., "The S/KEY One-Time Password System",
      RFC 1760, February 1995.
 [6]  Rivest, R., "The MD5 Message-Digest Algorithm", RFC 1321,
      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

Haller Standards Track [Page 9] RFC 2289 A One-Time Password System February 1998

 [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.
 [10] Atkinson, R., "Security Architecture for the Internet Protocol",
      RFC 1825, August 1995.
 [11] Atkinson, R., "IP Authentication Header", RFC 1826, August
      1995.
 [12] Atkinson, R., "IP Encapsulating Security Payload (ESP)", RFC
      1827, August 1995.

Haller Standards Track [Page 10] RFC 2289 A One-Time Password System February 1998

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
 Philip J. Nesser II
 Nesser & Nesser Consulting
 13501 100th Ave NE
 Suite 5202
 Kirkland, WA 98034, USA
 Phone: +1 206 481 4303
 EMail: pjnesser@martigny.ai.mit.edu
 Mike Straw
 Bellcore
 RRC 1A-225
 445 Hoes Lane
 Piscataway, NJ 08854-4182
 Phone:  +1 908 699-5212
 EMail:  mess@bellcore.com

Haller Standards Track [Page 11] RFC 2289 A One-Time Password System February 1998

Appendix A - Interfaces to Secure Hash Algorithms

 Original interoperability tests provided valuable insights into the
 subtle problems which occur when converting protocol specifications
 into running code.  In particular, the manipulation of bit ordered
 data is dependent on the architecture of the hardware, specifically
 the way in which a computer stores multi-byte data.  The method is
 typically called big or little "endian."  A big endian machine stores
 data with the most significant byte first, while a little endian
 machine stores the least significant byte first.  Thus, on a big
 endian machine data is stored left to right, while little endian
 machines store data right to left.
 For example, the four byte value 0x11AABBCC is stored in a big endian
 machine as the following series of four bytes, "0x11", "0xAA",
 "0xBB", and "0xCC", while on a little endian machine the value would
 be stored as "0xCC", "0xBB", "0xAA", and "0x11".
 For historical reasons, and to promote interoperability with existing
 implementations, it was decided that ALL hashes incorporated into the
 OTP protocol MUST store the output of their hash function in LITTLE
 ENDIAN format BEFORE the bit folding to 64 bits occurs.  This is done
 in the implementations of MD4 and MD5 (see references [2] and [6]),
 while it must be explicitly done for the implementation of SHA1 (see
 reference [7]).
 Any future hash functions implemented into the OTP protocol SHOULD
 provide a similar reference fragment of code to allow independent
 implementations to operate successfully.
 MD4 Message Digest (see reference [2])
   MD4_CTX md;
   unsigned char result[16];
   strcpy(buf, seed);     /* seed must be in lower case */
   strcat(buf, passwd);
   MD4Init(&md);
   MD4Update(&md, (unsigned char *)buf, strlen(buf));
   MD4Final(result, &md);
   /* Fold the 128 bit result to 64 bits */
   for (i = 0; i < 8; i++)
           result[i] ^= result[i+8];

Haller Standards Track [Page 12] RFC 2289 A One-Time Password System February 1998

MD5 Message Digest (see reference [6])

   MD5_CTX md;
   unsigned char result[16];
   strcpy(buf, seed);     /* seed must be in lower case */
   strcat(buf, passwd);
   MD5Init(&md);
   MD5Update(&md, (unsigned char *)buf, strlen(buf));
   MD5Final(result, &md);
   /* Fold the 128 bit result to 64 bits */
   for (i = 0; i < 8; i++)
           result[i] ^= result[i+8];

SHA Secure Hash Algorithm (see reference [7])

   SHA_INFO sha;
   unsigned char result[16];
   strcpy(buf, seed);     /* seed must be in lower case */
   strcat(buf, passwd);
   sha_init(&sha);
   sha_update(&sha, (unsigned char *)buf, strlen(buf));
   sha_final(&sha);       /* NOTE:  no result buffer */
   /* Fold the 160 bit result to 64 bits */
   sha.digest[0] ^= sha.digest[2];
   sha.digest[1] ^= sha.digest[3];
   sha.digest[0] ^= sha.digest[4];
   /*
    * copy the resulting 64 bits to the result buffer in little endian
    * fashion (analogous to the way MD4Final() and MD5Final() do).
    */
   for (i = 0, j = 0; j < 8; i++, j += 4)
   {
           result[j]   = (unsigned char)(sha.digest[i] & 0xff);
           result[j+1] = (unsigned char)((sha.digest[i] >> 8) & 0xff);
           result[j+2] = (unsigned char)((sha.digest[i] >> 16) & 0xff);
           result[j+3] = (unsigned char)((sha.digest[i] >> 24) & 0xff);
   }

Haller Standards Track [Page 13] RFC 2289 A One-Time Password System February 1998

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 sensitive.  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( 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.

Haller Standards Track [Page 14] RFC 2289 A One-Time Password System February 1998

Appendix C - OTP Verification Examples

 This appendix provides a series of inputs and correct outputs for all
 three of the defined OTP cryptographic hashes, specifically MD4, MD5,
 and SHA1.  This document is intended to be used by developers for
 interoperability checks when creating generators or servers.  Output
 is provided in both hexadecimal notation and the six word encoding
 documented in Appendix D.
 GENERAL CHECKS
 Note that the output given for these checks is not intended to be
 taken literally, but describes the type of action that should be
 taken.
 Pass Phrase Length

Input:

 Pass Phrase: Too_short
 Seed: iamvalid
 Count: 99
 Hash: ANY

Output:

 ERROR:  Pass Phrase too short

Input:

 Pass Phrase:
   1234567890123456789012345678901234567890123456789012345678901234
 Seed: iamvalid
 Count: 99
 Hash: ANY

Output:

 WARNING: Pass Phrase longer than the recommended maximum length of

63

Seed Values

Input:

 Pass Phrase:  A_Valid_Pass_Phrase
 Seed: Length_Okay
 Count: 99
 Hash: ANY

Output:

 ERROR: Seed must be purely alphanumeric

Input:

 Pass Phrase:  A_Valid_Pass_Phrase
 Seed: LengthOfSeventeen

Haller Standards Track [Page 15] RFC 2289 A One-Time Password System February 1998

 Count: 99
 Hash: ANY

Output:

 ERROR: Seed must be between 1 and 16 characters in length

Input:

 Pass Phrase:  A_Valid_Pass_Phrase
 Seed: A Seed
 Count: 99
 Hash: ANY

Output:

 ERROR: Seed must not contain any spaces

Parity Calculations

Input:

 Pass Phrase: A_Valid_Pass_Phrase
 Seed: AValidSeed
 Count: 99
 Hash: MD5

Output:

 Hex: 85c43ee03857765b
 Six Word(CORRECT):          FOWL KID MASH DEAD DUAL OAF
 Six Word(INCORRECT PARITY): FOWL KID MASH DEAD DUAL NUT
 Six Word(INCORRECT PARITY): FOWL KID MASH DEAD DUAL O
 Six Word(INCORRECT PARITY): FOWL KID MASH DEAD DUAL OAK

Haller Standards Track [Page 16] RFC 2289 A One-Time Password System February 1998

MD4 ENCODINGS

Pass Phrase Seed Cnt Hex Six Word Format

This is a test. TeSt 0 D185 4218 EBBB 0B51

                                         ROME MUG FRED SCAN LIVE LACE

This is a test. TeSt 1 6347 3EF0 1CD0 B444

                                         CARD SAD MINI RYE COL KIN

This is a test. TeSt 99 C5E6 1277 6E6C 237A

                                         NOTE OUT IBIS SINK NAVE MODE

AbCdEfGhIjK alpha1 0 5007 6F47 EB1A DE4E

                                         AWAY SEN ROOK SALT LICE MAP

AbCdEfGhIjK alpha1 1 65D2 0D19 49B5 F7AB

                                         CHEW GRIM WU HANG BUCK SAID

AbCdEfGhIjK alpha1 99 D150 C82C CE6F 62D1

                                         ROIL FREE COG HUNK WAIT COCA

OTP's are good correct 0 849C 79D4 F6F5 5388

                                         FOOL STEM DONE TOOL BECK NILE

OTP's are good correct 1 8C09 92FB 2508 47B1

                                         GIST AMOS MOOT AIDS FOOD SEEM

OTP's are good correct 99 3F3B F4B4 145F D74B

                                         TAG SLOW NOV MIN WOOL KENO

Haller Standards Track [Page 17] RFC 2289 A One-Time Password System February 1998

MD5 ENCODINGS

Pass Phrase Seed Cnt Hex Six Word Format

This is a test. TeSt 0 9E87 6134 D904 99DD

                                         INCH SEA ANNE LONG AHEM TOUR

This is a test. TeSt 1 7965 E054 36F5 029F

                                         EASE OIL FUM CURE AWRY AVIS

This is a test. TeSt 99 50FE 1962 C496 5880

                                         BAIL TUFT BITS GANG CHEF THY

AbCdEfGhIjK alpha1 0 8706 6DD9 644B F206

                                         FULL PEW DOWN ONCE MORT ARC

AbCdEfGhIjK alpha1 1 7CD3 4C10 40AD D14B

                                         FACT HOOF AT FIST SITE KENT

AbCdEfGhIjK alpha1 99 5AA3 7A81 F212 146C

                                         BODE HOP JAKE STOW JUT RAP

OTP's are good correct 0 F205 7539 43DE 4CF9

                                         ULAN NEW ARMY FUSE SUIT EYED

OTP's are good correct 1 DDCD AC95 6F23 4937

                                         SKIM CULT LOB SLAM POE HOWL

OTP's are good correct 99 B203 E28F A525 BE47

                                         LONG IVY JULY AJAR BOND LEE

SHA1 ENCODINGS

Pass Phrase Seed Cnt Hex Six Word Format

This is a test. TeSt 0 BB9E 6AE1 979D 8FF4

                                         MILT VARY MAST OK SEES WENT

This is a test. TeSt 1 63D9 3663 9734 385B

                                         CART OTTO HIVE ODE VAT NUT

This is a test. TeSt 99 87FE C776 8B73 CCF9

                                         GAFF WAIT SKID GIG SKY EYED

AbCdEfGhIjK alpha1 0 AD85 F658 EBE3 83C9

                                         LEST OR HEEL SCOT ROB SUIT

AbCdEfGhIjK alpha1 1 D07C E229 B5CF 119B

                                         RITE TAKE GELD COST TUNE RECK

AbCdEfGhIjK alpha1 99 27BC 7103 5AAF 3DC6

                                         MAY STAR TIN LYON VEDA STAN

OTP's are good correct 0 D51F 3E99 BF8E 6F0B

                                         RUST WELT KICK FELL TAIL FRAU

OTP's are good correct 1 82AE B52D 9437 74E4

                                         FLIT DOSE ALSO MEW DRUM DEFY

OTP's are good correct 99 4F29 6A74 FE15 67EC

                                         AURA ALOE HURL WING BERG WAIT

Haller Standards Track [Page 18] RFC 2289 A One-Time Password System February 1998

Appendix D - 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", "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",

Haller Standards Track [Page 19] RFC 2289 A One-Time Password System February 1998

"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", "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",

Haller Standards Track [Page 20] RFC 2289 A One-Time Password System February 1998

"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", "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",

Haller Standards Track [Page 21] RFC 2289 A One-Time Password System February 1998

"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", "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",

Haller Standards Track [Page 22] RFC 2289 A One-Time Password System February 1998

"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", "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",

Haller Standards Track [Page 23] RFC 2289 A One-Time Password System February 1998

"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", "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 Standards Track [Page 24] RFC 2289 A One-Time Password System February 1998

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Haller Standards Track [Page 25]

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