'\"
'\" Generated from file 'md5\&.man' by tcllib/doctools with format 'nroff'
'\" Copyright (c) 2003, Pat Thoyts <patthoyts@users\&.sourceforge\&.net>
'\"
.TH "md5" n 2\&.0\&.9 tcllib "MD5 Message-Digest Algorithm"
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.BS
.SH NAME
md5 \- MD5 Message-Digest Algorithm
.SH SYNOPSIS
package require \fBTcl 8\&.5 9\fR
.sp
package require \fBmd5 ?2\&.0\&.9?\fR
.sp
\fB::md5::md5\fR ?\fI-hex\fR? [ \fI-channel channel\fR | \fI-file filename\fR | \fIstring\fR ]
.sp
\fB::md5::hmac\fR ?\fI-hex\fR? \fI-key key\fR [ \fI-channel channel\fR | \fI-file filename\fR | \fIstring\fR ]
.sp
\fB::md5::MD5Init\fR
.sp
\fB::md5::MD5Update\fR \fItoken\fR \fIdata\fR
.sp
\fB::md5::MD5Final\fR \fItoken\fR
.sp
\fB::md5::HMACInit\fR \fIkey\fR
.sp
\fB::md5::HMACUpdate\fR \fItoken\fR \fIdata\fR
.sp
\fB::md5::HMACFinal\fR \fItoken\fR
.sp
.BE
.SH DESCRIPTION
.PP
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\&.
.PP
If you have \fBcritcl\fR and have built the \fBtcllibc\fR
package then the implementation of the hashing function will be
performed by compiled code\&. Alternatively if you have either
\fBcryptkit\fR or \fBTrf\fR then either of these is used to
accelerate the digest computation\&. If no suitable compiled package is
available then the pure-Tcl implementation is used\&. The
programming interface remains the same in all cases\&.
.PP
\fINote\fR 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 \fI-hex\fR option to the
\fBmd5\fR command\&.
.PP
\fIBEWARE\fR
The commands in this package expect binary data as their input\&.
When a \fB-file\fR is provided then this is ensured by the commands
themselves, as they open the referenced file in binary mode\&.
When literal data, or a \fB-channel\fR are provided instead, then the
command's \fIcaller is responsible\fR for ensuring this fact\&.
The necessary conversion command is \fBencoding convertto utf-8 $string\fR\&.
.PP
\fIATTENTION\fR, there is a \fITcl 9 COMPATIBILITY ISSUE\fR here\&.
.PP
\fITcl 8\&.x silently mishandles\fR non-binary input by cutting it
internally to size\&. I\&.e\&. by only using the low byte of a higher unicode point\&.
No error is thrown, the \fIresult is simply wrong\fR\&.
.PP
\fITcl 9 throws an error\fR instead, i\&.e\&.
.CS

expected byte sequence but character <location> was \&.\&.\&.
.CE
.SH COMMANDS
.TP
\fB::md5::md5\fR ?\fI-hex\fR? [ \fI-channel channel\fR | \fI-file filename\fR | \fIstring\fR ]
Calculate the MD5 digest of the binary data given in string\&. This is returned
as a binary string by default\&. Giving the \fI-hex\fR option will
return a hexadecimal encoded version of the digest\&.
.sp
The data to be hashed can be specified either as a string argument to
the \fBmd5\fR command, or as a filename or a pre-opened channel\&. If the
\fI-filename\fR argument is given then the file is opened, the data read
and hashed and the file is closed\&. If the \fI-channel\fR argument is
given then data is read from the channel until the end of file\&. The
channel is not closed\&.
.sp
Only one of \fI-file\fR, \fI-channel\fR or \fIstring\fR should be given\&.
.TP
\fB::md5::hmac\fR ?\fI-hex\fR? \fI-key key\fR [ \fI-channel channel\fR | \fI-file filename\fR | \fIstring\fR ]
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 \fI-key\fR are as
for the \fB::md5::md5\fR command\&.
.PP
.SH "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 \fBMD5Init\fR to obtain a token and then call
\fBMD5Update\fR as many times as required to add data to the hash\&. To
release any resources and obtain the hash value, you then call
\fBMD5Final\fR\&. An equivalent set of functions gives you a keyed digest
(HMAC)\&.
.TP
\fB::md5::MD5Init\fR
Begins a new MD5 hash\&. Returns a token ID that must be used for the
remaining functions\&.
.TP
\fB::md5::MD5Update\fR \fItoken\fR \fIdata\fR
Add data to the hash identified by token\&. Calling
\fIMD5Update $token "abcd"\fR is equivalent to calling
\fIMD5Update $token "ab"\fR followed by
\fIMD5Update $token "cb"\fR\&. See \fBEXAMPLES\fR\&.
.TP
\fB::md5::MD5Final\fR \fItoken\fR
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\&.
.TP
\fB::md5::HMACInit\fR \fIkey\fR
This is equivalent to the \fB::md5::MD5Init\fR command except that
it requires the key that will be included in the HMAC\&.
.TP
\fB::md5::HMACUpdate\fR \fItoken\fR \fIdata\fR
.TP
\fB::md5::HMACFinal\fR \fItoken\fR
These commands are identical to the MD5 equivalent commands\&.
.PP
.SH EXAMPLES
.CS


% md5::md5 -hex "Tcl does MD5"
8AAC1EE01E20BB347104FABB90310433

.CE
.CS


% md5::hmac -hex -key Sekret "Tcl does MD5"
35BBA244FD56D3EDF5F3C47474DACB5D

.CE
.CS


% set tok [md5::MD5Init]
::md5::1
% md5::MD5Update $tok "Tcl "
% md5::MD5Update $tok "does "
% md5::MD5Update $tok "MD5"
% md5::Hex [md5::MD5Final $tok]
8AAC1EE01E20BB347104FABB90310433

.CE
.SH REFERENCES
.IP [1]
Rivest, R\&., "The MD5 Message-Digest Algorithm", RFC 1321, MIT and
RSA Data Security, Inc, April 1992\&.
(\fIhttp://www\&.rfc-editor\&.org/rfc/rfc1321\&.txt\fR)
.IP [2]
Rivest, R\&., "The MD4 Message Digest Algorithm", RFC 1320, MIT,
April 1992\&. (\fIhttp://www\&.rfc-editor\&.org/rfc/rfc1320\&.txt\fR)
.IP [3]
Krawczyk, H\&., Bellare, M\&. and Canetti, R\&. "HMAC: Keyed-Hashing for
Message Authentication", RFC 2104, February 1997\&.
(\fIhttp://www\&.rfc-editor\&.org/rfc/rfc2104\&.txt\fR)
.PP
.SH "BUGS, IDEAS, FEEDBACK"
This document, and the package it describes, will undoubtedly contain
bugs and other problems\&.
Please report such in the category \fImd5\fR of the
\fITcllib Trackers\fR [http://core\&.tcl\&.tk/tcllib/reportlist]\&.
Please also report any ideas for enhancements you may have for either
package and/or documentation\&.
.PP
When proposing code changes, please provide \fIunified diffs\fR,
i\&.e the output of \fBdiff -u\fR\&.
.PP
Note further that \fIattachments\fR are strongly preferred over
inlined patches\&. Attachments can be made by going to the \fBEdit\fR
form of the ticket immediately after its creation, and then using the
left-most button in the secondary navigation bar\&.
.SH "SEE ALSO"
md4, sha1
.SH KEYWORDS
hashing, md5, message-digest, rfc 1320, rfc 1321, rfc 2104, security
.SH CATEGORY
Hashes, checksums, and encryption
.SH COPYRIGHT
.nf
Copyright (c) 2003, Pat Thoyts <patthoyts@users\&.sourceforge\&.net>

.fi
