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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 implementa-tions. implementations.
       tions. 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 pro-gramming programming
       gramming  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 func-tions functions
       tions 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 com-pletes completes
              pletes 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/rfc132_.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/rfc21_4.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://source -
       forge.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)