Provided by: tcllib_1.15-dfsg-2_all 
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>