md5(3tcl) MD5 Message-Digest Algorithm md5(3tcl)______________________________________________________________________________NAMEmd5 - MD5 Message-Digest Algorithm
SYNOPSIS
package require Tcl 8.2
package require md5 ?2.0.7?
::md5::md5 ?-hex? [ -channel channel | -file filename | string ]
::md5::hmac ?-hex? -key key [ -channel channel | -file filename |
string ]
::md5::MD5Init
::md5::MD5Update token data
::md5::MD5Final token
::md5::HMACInit key
::md5::HMACUpdate token data
::md5::HMACFinal token
_________________________________________________________________DESCRIPTION
This package is an implementation in Tcl of the MD5 message-digest
algorithm as described in RFC 1321 (1). This algorithm takes an arbi‐
trary quantity of data and generates a 128-bit message digest from the
input. The MD5 algorithm is related to the MD4 algorithm (2) but has
been strengthened against certain types of potential attack. MD5 should
be used in preference to MD4 for new applications.
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 you have either cryptkit or Trf then either of these
can be used to accelerate the digest computation. If no suitable com‐
piled package is available then the pure-Tcl implementation wil be
used. The programming interface remains the same in all cases.
Note the previous version of this package always returned a hex encoded
string. This has been changed to simplify the programming interface and
to make this version more compatible with other implementations. To
obtain the previous usage, either explicitly specify package version 1
or use the -hex option to the md5 command.
COMMANDS
::md5::md5 ?-hex? [ -channel channel | -file filename | string ]
Calculate the MD5 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 md5 command, or as a filename or a pre-opened chan‐
nel. 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.
::md5::hmac ?-hex? -key key [ -channel channel | -file filename |
string ]
Calculate an Hashed Message Authentication digest (HMAC) using
the MD5 digest algorithm. HMACs are described in RFC 2104 (3)
and provide an MD5 digest that includes a key. All options other
than -key are as for the ::md5::md5 command.
PROGRAMMING INTERFACE
For the programmer, the MD5 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 MD5 hash operates on a token (equivalent to the
bucket). You call MD5Init to obtain a token and then call MD5Update as
many times as required to add data to the hash. To release any
resources and obtain the hash value, you then call MD5Final. An equiva‐
lent set of functions gives you a keyed digest (HMAC).
::md5::MD5Init
Begins a new MD5 hash. Returns a token ID that must be used for
the remaining functions.
::md5::MD5Update token data
Add data to the hash identified by token. Calling MD5Update
$token "abcd" is equivalent to calling MD5Update $token "ab"
followed by MD5Update $token "cb". See EXAMPLES.
::md5::MD5Final 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 MD5 digest value.
::md5::HMACInit key
This is equivalent to the ::md5::MD5Init command except that it
requires the key that will be included in the HMAC.
::md5::HMACUpdate token data
::md5::HMACFinal token
These commands are identical to the MD5 equivalent commands.
EXAMPLES
% md5::md5 -hex "Tcl does MD5"
8AAC1EE01E20BB347104FABB90310433
% md5::hmac -hex -key Sekret "Tcl does MD5"
35BBA244FD56D3EDF5F3C47474DACB5D
% set tok [md5::MD5Init]
::md5::1
% md5::MD5Update $tok "Tcl "
% md5::MD5Update $tok "does "
% md5::MD5Update $tok "MD5"
% md5::Hex [md5::MD5Final $tok]
8AAC1EE01E20BB347104FABB90310433
REFERENCES
[1] 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)
[2] Rivest, R., "The MD4 Message Digest Algorithm", RFC 1320, MIT,
April 1992. (http://www.rfc-editor.org/rfc/rfc1320.txt)
[3] 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 md5 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, sha1
KEYWORDS
hashing, md5, message-digest, rfc 1320, rfc 1321, rfc 2104, security
CATEGORY
Hashes, checksums, and encryption
COPYRIGHT
Copyright (c) 2003, Pat Thoyts <patthoyts@users.sourceforge.net>
md5 2.0.7 md5(3tcl)
