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
       replacement 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
       implementation 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
              argument to the ripemd128 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.

       ::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
              command.

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
       implementation 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

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

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.kuleuven.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-
              editor.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://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, 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>




ripemd                               1.0.3                        ripemd128(n)
