md5(n)                   MD5 Message-Digest Algorithm                   md5(n)



______________________________________________________________________________

NAME
       md5 - MD5 Message-Digest Algorithm

SYNOPSIS
       package require Tcl  8.2

       package require md5  ?2.0.7?

       ::md5::md5 ?-hex? [ -channel channel | -file filename | string ]

       ::md5::hmac ?-hex? -key key [ -channel channel | -file filename |
       string ]

       ::md5::MD5Init

       ::md5::MD5Update token data

       ::md5::MD5Final token

       ::md5::HMACInit key

       ::md5::HMACUpdate token data

       ::md5::HMACFinal token

_________________________________________________________________

DESCRIPTION
       This package is an implementation in Tcl of the MD5 message-digest
       algorithm as described in RFC 1321 (1). This algorithm takes an
       arbitrary quantity of data and generates a 128-bit message digest from
       the input. The MD5 algorithm is related to the MD4 algorithm (2) but
       has been strengthened against certain types of potential attack. MD5
       should be used in preference to MD4 for new applications.

       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 you have either cryptkit or Trf then either of
       these can be used to accelerate the digest computation. If no suitable
       compiled package is available then the pure-Tcl implementation wil be
       used. The programming interface remains the same in all cases.

       Note the previous version of this package always returned a hex encoded
       string. This has been changed to simplify the programming interface and
       to make this version more compatible with other implementations. To
       obtain the previous usage, either explicitly specify package version 1
       or use the -hex option to the md5 command.

COMMANDS
       ::md5::md5 ?-hex? [ -channel channel | -file filename | string ]
              Calculate the MD5 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 md5 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.

       ::md5::hmac ?-hex? -key key [ -channel channel | -file filename |
       string ]
              Calculate an Hashed Message Authentication digest (HMAC) using
              the MD5 digest algorithm. HMACs are described in RFC 2104 (3)
              and provide an MD5 digest that includes a key. All options other
              than -key are as for the ::md5::md5 command.

PROGRAMMING INTERFACE
       For the programmer, the MD5 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 MD5 hash operates on a token (equivalent to the
       bucket). You call MD5Init to obtain a token and then call MD5Update as
       many times as required to add data to the hash. To release any
       resources and obtain the hash value, you then call MD5Final. An
       equivalent set of functions gives you a keyed digest (HMAC).

       ::md5::MD5Init
              Begins a new MD5 hash. Returns a token ID that must be used for
              the remaining functions.

       ::md5::MD5Update token data
              Add data to the hash identified by token. Calling MD5Update
              $token "abcd" is equivalent to calling MD5Update $token "ab"
              followed by MD5Update $token "cb". See EXAMPLES.

       ::md5::MD5Final 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 MD5 digest value.

       ::md5::HMACInit key
              This is equivalent to the ::md5::MD5Init command except that it
              requires the key that will be included in the HMAC.

       ::md5::HMACUpdate token data

       ::md5::HMACFinal token
              These commands are identical to the MD5 equivalent commands.

EXAMPLES
              % md5::md5 -hex "Tcl does MD5"
              8AAC1EE01E20BB347104FABB90310433



              % md5::hmac -hex -key Sekret "Tcl does MD5"
              35BBA244FD56D3EDF5F3C47474DACB5D



              % set tok [md5::MD5Init]
              ::md5::1
              % md5::MD5Update $tok "Tcl "
              % md5::MD5Update $tok "does "
              % md5::MD5Update $tok "MD5"
              % md5::Hex [md5::MD5Final $tok]
              8AAC1EE01E20BB347104FABB90310433


REFERENCES
       [1]    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)

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

       [3]    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 md5 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
       md4, sha1

KEYWORDS
       hashing, md5, message-digest, rfc 1320, rfc 1321, rfc 2104, security

CATEGORY
       Hashes, checksums, and encryption

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




md5                                  2.0.7                              md5(n)
