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

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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

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DESCRIPTION

       This  package  is  an implementation in Tcl of the MD5 message-digest algorithm as described in RFC 1321 (1). This algorithm takes an arbi-
       trary 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 com-
       piled 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  ver-
       sion 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-edi-
	      tor.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)