


ripemd128(n)     RIPEMD Message-Digest Algorithm     ripemd128(n)


______________________________________________________________________________

NAME
       ripemd128 - RIPEMD-128 Message-Digest Algorithm

SYNOPSIS
       package require Tcl  8.2

       package require ripemd128  ?1.0.3?

       ::ripemd::ripemd128 ?-hex? [ -channel channel | -file filename | string
       ]

       ::ripemd::hmac128 ?-hex? -key key [ -channel channel | -file filename |
       string ]

       ::ripemd::RIPEMD128Init

       ::ripemd::RIPEMD128Update token data

       ::ripemd::RIPEMD128Final token

       ::ripemd::RIPEHMAC128Init key

       ::ripemd::RIPEHMAC128Update token data

       ::ripemd::RIPEHMAC128Final token

_________________________________________________________________

DESCRIPTION
       This  package  is  an  implementation in Tcl of the RIPEMD-128 message-
       digest algorithm (1). This algorithm takes  an  arbitrary  quantity  of
       data  and  generates  a  128-bit  message  digest  from  the input. The
       RIPEMD-128 algorithm is based upon the MD4 algorithm  (2,  4)  but  has
       been  cryptographically  strengthened against weaknesses that have been
       found in MD4 (4). RIPEMD-128 has been designed to be a drop-in replace-
       ment  for MD4 and MD5 (5). If security is the major consideration, then
       RIPEMD-160 or SHA1 should be considered.

       This package will use Trf  to  accelerate  the  digest  computation  if
       available. In the absence of an accelerator package the pure-Tcl imple-
       mentation will be used.

COMMANDS
       ::ripemd::ripemd128 ?-hex? [ -channel channel | -file filename | string
       ]
              Calculate  the  RIPEMD-128  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  argu-
              ment  to the ripemd128 command, or as a filename or a pre-opened
              channel. If the -filename argument is given  then  the  file  is



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ripemd128(n)     RIPEMD Message-Digest Algorithm     ripemd128(n)


              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.

       ::ripemd::hmac128 ?-hex? -key key [ -channel channel | -file filename |
       string ]
              Calculate  an  Hashed Message Authentication digest (HMAC) using
              the RIPEMD-128 digest algorithm. HMACs are described in RFC 2104
              (6)  and  provide  a  RIPEMD-128 digest that includes a key. All
              options other than -key are as for the ::ripemd::ripemd128  com-
              mand.


PROGRAMMING INTERFACE
       For the programmer, hash functions can be viewed as a bucket into which
       one pours data. When you have finished, you extract  a  value  that  is
       uniquely  derived  from  the  data that was poured into the bucket. The
       programming interface to the hash operates on a  token  (equivalent  to
       the  bucket).  You  call  RIPEMD128Init to obtain a token and then call
       RIPEMD128Update as many times as required to add data to the  hash.  To
       release  any  resources  and  obtain  the  hash  value,  you  then call
       RIPEMD128Final. An equivalent set of functions gives you a keyed digest
       (HMAC).

       If  you  have critcl and have built the tcllibc package then the imple-
       mentation of the hashing function will be performed by  compiled  code.
       Alternatively if both the Trf and Memchan extensions are available then
       these will be used. Finally the  package  will  revert  to  a  pure-Tcl
       implementation.  The programming interface remains the same, however.

       ::ripemd::RIPEMD128Init
              Begins  a  new  RIPEMD-128 hash. Returns a token ID that must be
              used for the remaining functions.

       ::ripemd::RIPEMD128Update token data
              Add  data   to   the   hash   identified   by   token.   Calling
              RIPEMD128Update   $token   "abcd"   is   equivalent  to  calling
              RIPEMD128Update $token "ab" followed by  RIPEMD128Update  $token
              "cb". See EXAMPLES.

       ::ripemd::RIPEMD128Final 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 RIPEMD-128 digest value.

       ::ripemd::RIPEHMAC128Init key
              This is equivalent to the ::ripemd::RIPEMD128Init command except
              that it requires the key that will be included in the HMAC.

       ::ripemd::RIPEHMAC128Update token data




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ripemd128(n)     RIPEMD Message-Digest Algorithm     ripemd128(n)


       ::ripemd::RIPEHMAC128Final token
              These  commands  are  identical to the RIPEMD128 equivalent com-
              mands.


EXAMPLES
       % ripemd::ripemd128 -hex "Tcl does RIPEMD-128"
       3cab177bae65205d81e7978f63556c63


       % ripemd::hmac128 -hex -key Sekret "Tcl does RIPEMD-128"
       b359dc5971a05beea0be7b106b30e389


       % set tok [ripemd::RIPEMD128Init]
       ::ripemd::1
       % ripemd::RIPEMD128Update $tok "Tcl "
       % ripemd::RIPEMD128Update $tok "does "
       % ripemd::RIPEMD128Update $tok "RIPEMD-128"
       % ripemd::Hex [ripemd::RIPEMD128Final $tok]
       3cab177bae65205d81e7978f63556c63


REFERENCES
       [1]    H.  Dobbertin,  A.  Bosselaers,  B.  Preneel,   "RIPEMD-160,   a
              strengthened    version    of   RIPEMD"   http://www.esat.kuleu-
              ven.ac.be/~cosicart/pdf/AB-9601/AB-9601.pdf

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

       [3]    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.

       [4]    Dobbertin, H., "Cryptanalysis of MD4", Journal of Cryptology vol
              11 (4), pp. 253-271 (1998)

       [5]    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)

       [6]    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 ripemd 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.




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ripemd128(n)     RIPEMD Message-Digest Algorithm     ripemd128(n)


SEE ALSO
       md4, md5, ripemd160, sha1

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

CATEGORY
       Hashes, checksums, and encryption

COPYRIGHT
       Copyright (c) 2004, Pat Thoyts <patthoyts@users.sourceforge.net>













































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