md5(n) 2.0.0 "Perform md5 hashing"
md5 - MD5 Message-Digest Algorithm
package require Tcl 8.2
package require md5 2.0
This package is an implementation in Tcl of the MD5 message-digest
algorithm as described in RFC 1321 (1). This algorithm takes
an arbitrary 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.
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::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 argument to
the md5 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.
- ::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.
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 equivalent set of functions gives you a keyed digest
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.
Begins a new MD5 hash. Returns a token ID that must be used for the
- ::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
- ::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.
% md5::md5 -hex "Tcl does MD5"
% md5::hmac -hex -key Sekret "Tcl does MD5"
% set tok [md5::MD5Init]
% md4::MD5Update $tok "Tcl "
% md4::MD5Update $tok "does "
% md4::MD5Update $tok "MD5"
% md4::Hex [md5::MD5Final $tok]
Rivest, R., "The MD5 Message-Digest Algorithm", RFC 1321, MIT and
RSA Data Security, Inc, April 1992.
Rivest, R., "The MD4 Message Digest Algorithm", RFC 1320, MIT,
April 1992. (http://www.rfc-editor.org/rfc/rfc1320.txt)
Krawczyk, H., Bellare, M. and Canetti, R. "HMAC: Keyed-Hashing for
Message Authentication", RFC 2104, February 1997.
hashing, md5, message-digest, rfc 1320, rfc 1321, rfc 2104, security
Copyright © 2003, Pat Thoyts <firstname.lastname@example.org>