md4(n)                   MD4 Message-Digest Algorithm                   md4(n)



______________________________________________________________________________

NAME
       md4 - MD4 Message-Digest Algorithm

SYNOPSIS
       package require Tcl  8.2

       package require md4  ?1.0?

       ::md4::md4 ?-hex? [ -channel channel | -file filename | string ]

       ::md4::hmac ?-hex? -key key [ -channel channel | -file filename |
       string ]

       ::md4::MD4Init

       ::md4::MD4Update token data

       ::md4::MD4Final token

       ::md4::HMACInit key

       ::md4::HMACUpdate token data

       ::md4::HMACFinal token

_________________________________________________________________

DESCRIPTION
       This package is an implementation in Tcl of the MD4 message-digest
       algorithm as described in RFC 1320 (1) and (2). This algorithm takes an
       arbitrary quantity of data and generates a 128-bit message digest from
       the input. The MD4 algorithm is faster but potentially weaker than the
       related MD5 algorithm (3).

       If you have critcl and have built the tcllibc package then the
       implementation of the hashing function will be performed by compiled
       code. Alternatively if cryptkit is available this will be used. If no
       accelerator package can be found then the pure-tcl implementation is
       used. The programming interface remains the same in all cases.

COMMANDS
       ::md4::md4 ?-hex? [ -channel channel | -file filename | string ]
              Calculate the MD4 digest of the data given in string. This is
              returned as a binary string by default. Giving the -hex option
              will return a hexadecimal encoded version of the digest.

              The data to be hashed can be specified either as a string
              argument to the md4 command, or as a filename or a pre-opened
              channel. If the -filename argument is given then the file is
              opened, the data read and hashed and the file is closed. If the
              -channel argument is given then data is read from the channel
              until the end of file. The channel is not closed.

              Only one of -file, -channel or string should be given.

       ::md4::hmac ?-hex? -key key [ -channel channel | -file filename |
       string ]
              Calculate an Hashed Message Authentication digest (HMAC) using
              the MD4 digest algorithm. HMACs are described in RFC 2104 (4)
              and provide an MD4 digest that includes a key. All options other
              than -key are as for the ::md4::md4 command.

PROGRAMMING INTERFACE
       For the programmer, the MD4 hash can be viewed as a bucket into which
       one pours data. When you have finished, you extract a value that is
       derived from the data that was poured into the bucket. The programming
       interface to the MD4 hash operates on a token (equivalent to the
       bucket). You call MD4Init to obtain a token and then call MD4Update as
       many times as required to add data to the hash. To release any
       resources and obtain the hash value, you then call MD4Final. An
       equivalent set of functions gives you a keyed digest (HMAC).

       ::md4::MD4Init
              Begins a new MD4 hash. Returns a token ID that must be used for
              the remaining functions.

       ::md4::MD4Update token data
              Add data to the hash identified by token. Calling MD4Update
              $token "abcd" is equivalent to calling MD4Update $token "ab"
              followed by MD4Update $token "cb". See EXAMPLES.

       ::md4::MD4Final token
              Returns the hash value and releases any resources held by this
              token. Once this command completes the token will be invalid.
              The result is a binary string of 16 bytes representing the 128
              bit MD4 digest value.

       ::md4::HMACInit key
              This is equivalent to the ::md4::MD4Init command except that it
              requires the key that will be included in the HMAC.

       ::md4::HMACUpdate token data

       ::md4::HMACFinal token
              These commands are identical to the MD4 equivalent commands.

EXAMPLES
              % md4::md4 -hex "Tcl does MD4"
              858da9b31f57648a032230447bd15f25



              % md4::hmac -hex -key Sekret "Tcl does MD4"
              c324088e5752872689caedf2a0464758



              % set tok [md4::MD4Init]
              ::md4::1
              % md4::MD4Update $tok "Tcl "
              % md4::MD4Update $tok "does "
              % md4::MD4Update $tok "MD4"
              % md4::Hex [md4::MD4Final $tok]
              858da9b31f57648a032230447bd15f25


REFERENCES
       [1]    Rivest, R., "The MD4 Message Digest Algorithm", RFC 1320, MIT,
              April 1992. (http://www.rfc-editor.org/rfc/rfc1320.txt)

       [2]    Rivest, R., "The MD4 message digest algorithm", in A.J.  Menezes
              and S.A. Vanstone, editors, Advances in Cryptology - CRYPTO '90
              Proceedings, pages 303-311, Springer-Verlag, 1991.

       [3]    Rivest, R., "The MD5 Message-Digest Algorithm", RFC 1321, MIT
              and RSA Data Security, Inc, April 1992.  (http://www.rfc-
              editor.org/rfc/rfc1321.txt)

       [4]    Krawczyk, H., Bellare, M. and Canetti, R. "HMAC: Keyed-Hashing
              for Message Authentication", RFC 2104, February 1997.
              (http://www.rfc-editor.org/rfc/rfc2104.txt)

BUGS, IDEAS, FEEDBACK
       This document, and the package it describes, will undoubtedly contain
       bugs and other problems.  Please report such in the category md4 of the
       Tcllib SF Trackers [http://sourceforge.net/tracker/?group_id=12883].
       Please also report any ideas for enhancements you may have for either
       package and/or documentation.

SEE ALSO
       md5, sha1

KEYWORDS
       hashing, md4, message-digest, rfc 1320, rfc 1321, rfc 2104, security

CATEGORY
       Hashes, checksums, and encryption

COPYRIGHT
       Copyright (c) 2003, Pat Thoyts <patthoyts@users.sourceforge.net>




md4                                  1.0.5                              md4(n)
