sha1 -
SHA1 Message-Digest Algorithm
package require Tcl 8.2
package require sha1 ? 2.0.3 ?
::sha1::sha1 ? -hex|-bin ? [ -channel channel | -file filename | string ]
::sha1::hmac key string
::sha1::hmac ? -hex|-bin ? -key key [ -channel channel | -file filename | string ]
::sha1::SHA1Init
::sha1::SHA1Update token data
::sha1::SHA1Final token
::sha1::HMACInit key
::sha1::HMACUpdate token data
::sha1::HMACFinal token
This package provides an implementation in Tcl of the SHA1
message-digest algorithm as specified by FIPS PUB 180-1 (1). This
algorithm takes a message and generates a 160-bit digest from the
input. The SHA1 algorithm is related to the MD4 algorithm (2) but has
been strengthend against certain types of cryptographic attack. SHA1
should be used in preference to MD4 or MD5 in new applications.
This package also includes support for creating keyed message-digests
using the HMAC algorithm from RFC 2104 (3) with SHA1 as the
message-digest.
-
::sha1::sha1 ? -hex|-bin ? [ -channel channel | -file filename | string ]
-
The command takes a message and returns the SHA1 digest of this message
as a hexadecimal string. You may request the result as binary data by
giving -bin.
The data to be hashed can be specified either as a string argument to
the sha1 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. NOTE use of the channel or filename
options results in the internal use of vwait. To avoid nested
event loops in Tk or tclhttpd applications you should use the
incremental programming API (see below).
Only one of -file, -channel or string should be given.
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::sha1::hmac key string
-
-
::sha1::hmac ? -hex|-bin ? -key key [ -channel channel | -file filename | string ]
-
Calculate an Hashed Message Authentication digest (HMAC) using the SHA1
digest algorithm. HMACs are described in RFC 2104 (3) and provide an SHA1
digest that includes a key. All options other than -key are as
for the ::sha1::sha1 command.
For the programmer, the SHA1 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 SHA1 hash operates on a token (equivalent to the
bucket). You call
SHA1Init to obtain a token and then call
SHA1Update as many times as required to add data to the hash. To
release any resources and obtain the hash value, you then call
SHA1Final. 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. Failing that if you have the Trf package then this can
be used otherwise there is a pure-tcl equivalent. The programming
interface remains the same in all cases.
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::sha1::SHA1Init
-
Begins a new SHA1 hash. Returns a token ID that must be used for the
remaining functions.
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::sha1::SHA1Update token data
-
Add data to the hash identified by token. Calling
SHA1Update $token "abcd" is equivalent to calling
SHA1Update $token "ab" followed by
SHA1Update $token "cb". See EXAMPLES.
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::sha1::SHA1Final 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 20 bytes representing the 160 bit SHA1
digest value.
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::sha1::HMACInit key
-
This is equivalent to the ::sha1::SHA1Init command except that
it requires the key that will be included in the HMAC.
-
::sha1::HMACUpdate token data
-
-
::sha1::HMACFinal token
-
These commands are identical to the SHA1 equivalent commands.
% sha1::sha1 "Tcl does SHA1"
285a6a91c45a9066bf39fcf24425796ef0b2a8bf
% sha1::hmac Sekret "Tcl does SHA1"
ae6251fa51b95b18cba2be95eb031d07475ff03c
% set tok [sha1::SHA1Init]
::sha1::1
% sha1::SHA1Update $tok "Tcl "
% sha1::SHA1Update $tok "does "
% sha1::SHA1Update $tok "SHA1"
% sha1::Hex [sha1::SHA1Final $tok]
285a6a91c45a9066bf39fcf24425796ef0b2a8bf
-
"Secure Hash Standard", National Institute of Standards
and Technology, U.S. Department Of Commerce, April 1995.
(http://www.itl.nist.gov/fipspubs/fip180-1.htm)
-
Rivest, R., "The MD4 Message Digest Algorithm", RFC 1320, MIT,
April 1992. (http://www.rfc-editor.org/rfc/rfc1320.txt)
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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)
This document, and the package it describes, will undoubtedly contain
bugs and other problems.
Please report such in the category
sha1 of the
http://sourceforge.net/tracker/?group_id=12883.
Please also report any ideas for enhancements you may have for either
package and/or documentation.
md4, md5, ripemd128, ripemd160
sha1, hashing, security, message-digest, FIPS 180-1, rfc 2104