SYNOPSIS

package require Tcl 8.2

package require ripemd160 ?1.0.5?

::ripemd::ripemd160 ?-hex? [ -channel channel | -file filename | string ]

::ripemd::hmac160 ?-hex? -key key [ -channel channel | -file filename | string ]

::ripemd::RIPEMD160Init

::ripemd::RIPEMD160Update token data

::ripemd::RIPEMD160Final token

::ripemd::RIPEHMAC160Init key

::ripemd::RIPEHMAC160Update token data

::ripemd::RIPEHMAC160Final token

---

DESCRIPTION

This package is an implementation in Tcl of the RIPEMD-160 message-digest algorithm (1). This algorithm takes an arbitrary quantity of data and generates a 160-bit message digest from the input. The RIPEMD-160 algorithm is based upon the MD4 algorithm (2, 4) but has been cryptographically strengthened against weaknesses that have been found in MD4 (4).

This package will use cryptkit or Trf to accelerate the digest computation if either package is available. In the absence of an accelerator package the pure-Tcl implementation will be used.

COMMANDS

::ripemd::ripemd160 ?-hex? [ -channel channel | -file filename | string ]

Calculate the RIPEMD-160 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 ripemd160 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::hmac160 ?-hex? -key key [ -channel channel | -file filename | string ]

Calculate an Hashed Message Authentication digest (HMAC) using the RIPEMD-160 digest algorithm. HMACs are described in RFC 2104 (5) and provide a RIPEMD-160 digest that includes a key. All options other than -key are as for the ::ripemd::ripemd160 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 RIPEMD160Init to obtain a token and then call RIPEMD160Update as many times as required to add data to the hash. To release any resources and obtain the hash value, you then call RIPEMD160Final. An equivalent set of functions gives you a keyed digest (HMAC).

::ripemd::RIPEMD160Init

Begins a new RIPEMD-160 hash. Returns a token ID that must be used for the remaining functions.

::ripemd::RIPEMD160Update token data

Add data to the hash identified by token. Calling RIPEMD160Update $token "abcd" is equivalent to calling RIPEMD160Update $token "ab" followed by RIPEMD160Update $token "cb". See EXAMPLES.

::ripemd::RIPEMD160Final 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 160 bit RIPEMD-160 digest value.

::ripemd::RIPEHMAC160Init key

This is equivalent to the ::ripemd::RIPEMD160Init command except that it requires the key that will be included in the HMAC.

::ripemd::RIPEHMAC160Update token data

::ripemd::RIPEHMAC160Final token

These commands are identical to the RIPEMD160 equivalent commands.

EXAMPLES

% ripemd::ripemd160 -hex "Tcl does RIPEMD-160"
0829dea75a1a7074c702896723fe37763481a0a7

% ripemd::hmac160 -hex -key Sekret "Tcl does RIPEMD-160"
bf0c927231733686731dddb470b64a9c23f7f53b

% set tok [ripemd::RIPEMD160Init]
::ripemd::1
% ripemd::RIPEMD160Update $tok "Tcl "
% ripemd::RIPEMD160Update $tok "does "
% ripemd::RIPEMD160Update $tok "RIPEMD-160"
% ripemd::Hex [ripemd::RIPEMD160Final $tok]
0829dea75a1a7074c702896723fe37763481a0a7

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]

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)

KEYWORDS

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

CATEGORY

Hashes, checksums, and encryption

COPYRIGHT

Copyright (c) 2004, Pat Thoyts <[email protected]>