md4 - MD4 Message-Digest Algorithm

package require Tcl 8.2 package require md4 ?1.0.2? ::md4::md4 ?-hex? [ -channel channel | -file filename | string ] ::md4::hmac ?-hex? -key key [ -channel channel | -file filename | string ] ::md4::MD4Init ::md4::MD4Update token data ::md4::MD4Final token ::md4::HMACInit key ::md4::HMACUpdate token data ::md4::HMACFinal token

This package is an implementation in Tcl of the MD4 message-digest algorithm as described in RFC 1320 (1) and (2). This algorithm takes an arbitrary quantity of data and generates a 128-bit message digest from the input. The MD4 algorithm is faster but potentially weaker than the related MD5 algorithm (3).

::md4::md4 ?-hex? [ -channel channel | -file filename | string ]

Calculate the MD4 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 md4 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.

::md4::hmac ?-hex? -key key [ -channel channel | -file filename | string ]

Calculate an Hashed Message Authentication digest (HMAC) using the MD4 digest algorithm. HMACs are described in RFC 2104 (4) and provide an MD4 digest that includes a key. All options other than -key are as for the ::md4::md4 command.

For the programmer, the MD4 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 programming interface to the MD4 hash operates on a token (equivalent to the bucket). You call MD4Init to obtain a token and then call MD4Update as many times as required to add data to the hash. To release any resources and obtain the hash value, you then call MD4Final. 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 - otherwise there is a pure-tcl equivalent. The programming interface remains the same, however.

::md4::MD4Init

Begins a new MD4 hash. Returns a token ID that must be used for the remaining functions.

::md4::MD4Update token data

Add data to the hash identified by token. Calling MD4Update $token "abcd" is equivalent to calling MD4Update $token "ab" followed by MD4Update $token "cb". See EXAMPLES.

::md4::MD4Final 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 MD4 digest value.

::md4::HMACInit key

This is equivalent to the ::md4::MD4Init command except that it requires the key that will be included in the HMAC.

::md4::HMACUpdate token data

::md4::HMACFinal token

These commands are identical to the MD4 equivalent commands.

% md4::md4 -hex "Tcl does MD4"
858DA9B31F57648A032230447BD15F25

% md4::hmac -hex -key Sekret "Tcl does MD4"
C324088E5752872689CAEDF2A0464758

% set tok [md4::MD4Init]
::md4::1
% md4::MD4Update $tok "Tcl "
% md4::MD4Update $tok "does "
% md4::MD4Update $tok "MD4"
% md4::Hex [md4::MD4Final $tok]
858DA9B31F57648A032230447BD15F25

[1]

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

[2]

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.

[3]

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)

[4]

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)

md5, sha1

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

Copyright (c) 2003, Pat Thoyts <patthoyts@users.sourceforge.net>