MD6(3p)        User Contributed Perl Documentation        MD6(3p)


NAME
       Digest::MD6 - Perl interface to the MD6 Algorithm

VERSION
       This document describes Digest::MD6 version 0.10

SYNOPSIS
         # Functional style
         use Digest::MD6 qw(md6 md6_hex md6_base64);

         $digest = md6($data);
         $digest = md6_hex($data);
         $digest = md6_base64($data);

         # OO style
         use Digest::MD6;

         $ctx = Digest::MD6->new;

         # Or set the hash length explicitly
         $ctx = Digest::MD6->new( 512 );

         $ctx->add($data);
         $ctx->addfile(*FILE);

         $digest = $ctx->digest;
         $digest = $ctx->hexdigest;
         $digest = $ctx->b64digest;

DESCRIPTION
       The "Digest::MD6" module allows you to use the MD6 Message
       Digest algorithm from within Perl programs. The algorithm
       takes as input a message of arbitrary length and produces
       as output a "fingerprint" or "message digest" of the
       input.

INTERFACE
       The "Digest::MD6" module provide a procedural interface
       for simple use, as well as an object oriented interface
       that can handle messages of arbitrary length and which can
       read files directly.

       FUNCTIONS

       The following functions are provided by the "Digest::MD6"
       module.  None of these functions are exported by default.

       The hash size (which defaults to 256 bits, 32 characters)
       can be set before calling these functions:

         $Digest::MD6::HASH_LENGTH = 512;

       md6($data,...)




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       This function will concatenate all arguments, calculate
       the MD6 digest of this " message ", and return it in
       binary form.  The returned string will be 16 bytes long.

       The result of md6(" a ", " b ", " c ") will be exactly the
       same as the result of md6(" abc ").

       md6_hex($data,...)

       Same as md6(), but will return the digest in hexadecimal
       form. The length of the returned string will be 32 and it
       will only contain characters from this set: '0'..'9' and
       'a'..'f'.

       md6_base64($data,...)

       Same as md6(), but will return the digest as a base64
       encoded string.  The length of the returned string will be
       22 and it will only contain characters from this set:
       'A'..'Z', 'a'..'z', '0'..'9', '+' and '/'.

       Note that the base64 encoded string returned is not padded
       to be a multiple of 4 bytes long.  If you want
       interoperability with other base64 encoded md6 digests you
       might want to append enough '=' characters to make the
       length a multiple of 4.

       Aliases

       As a shorthand for setting the hash length via
       $Digest::MD6::HASH_LENGTH a number of exportable aliases
       are available:

         md6_224 md6_224_base64 md6_224_hex
         md6_256 md6_256_base64 md6_256_hex
         md6_384 md6_384_base64 md6_384_hex
         md6_512 md6_512_base64 md6_512_hex

       These set the hash length before encoding, so instead of
       writing:

         {
           local $Digest::MD6::HASH_LENGTH = 512;
           my $hash = md6_hex( $data );
         }

       you can just:

         my $hash = md6_512_hex( $data );

METHODS
       The object oriented interface to "Digest::MD6" is
       described in this section.  After a "Digest::MD6" object
       has been created, you will add data to it and finally ask



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       for the digest in a suitable format.  A single object can
       be used to calculate multiple digests.

       The following methods are provided:

       $md6 = Digest::MD6->new

       The constructor returns a new "Digest::MD6" object which
       encapsulate the state of the MD6 message-digest algorithm.

       If called as an instance method (i.e. $md6->new) it will
       just reset the state the object to the state of a newly
       created object.  No new object is created in this case.

       The hash size will default to $Digest::MD6::HASH_LENGTH
       but can be overridden by passing a different value to the
       constructor:

         my $md6 = Digest::MD6->new( 128 );

       $md6->reset

       This is just an alias for $md6->new.

       $md6->clone

       This a copy of the $md6 object. It is useful when you do
       not want to destroy the digests state, but need an
       intermediate value of the digest, e.g. when calculating
       digests iteratively on a continuous data stream. Example:

         my $md6 = Digest::MD6->new;
         while (<>) {
           $md6->add($_);
           print " Line $.: ", $md6->clone->hexdigest, " \n ";
         }

       $md6->add($data,...)

       The $data provided as argument are appended to the message
       we calculate the digest for.  The return value is the $md6
       object itself.

       All these lines will have the same effect on the state of
       the $md6 object:

         $md6->add(" a "); $md6->add(" b "); $md6->add(" c ");
         $md6->add(" a ")->add(" b ")->add(" c ");
         $md6->add(" a ", " b ", " c ");
         $md6->add(" abc ");

       $md6->addfile($io_handle)

       The $io_handle will be read until EOF and its content



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       appended to the message we calculate the digest for.  The
       return value is the $md6 object itself.

       The addfile() method will croak() if it fails reading data
       for some reason.  If it croaks it is unpredictable what
       the state of the $md6 object will be in. The addfile()
       method might have been able to read the file partially
       before it failed.  It is probably wise to discard or reset
       the $md6 object if this occurs.

       In most cases you want to make sure that the $io_handle is
       in "binmode" before you pass it as argument to the
       addfile() method.

       $md6->add_bits($data, $nbits)

       $md6->add_bits($bitstring)

       Since the MD6 algorithm is byte oriented you might only
       add bits as multiples of 8, so you probably want to just
       use add() instead.  The add_bits() method is provided for
       compatibility with other digest implementations.  See
       Digest for description of the arguments that add_bits()
       take.

       $md6->digest

       Return the binary digest for the message.  The returned
       string will be 16 bytes long.

       Note that the "digest" operation is effectively a
       destructive, read-once operation. Once it has been
       performed, the "Digest::MD6" object is automatically
       "reset" and can be used to calculate another digest value.
       Call $md6->clone->digest if you want to calculate the
       digest without resetting the digest state.

       $md6->hexdigest

       Same as $md6->digest, but will return the digest in
       hexadecimal form. The length of the returned string will
       be 32 and it will only contain characters from this set:
       '0'..'9' and 'a'..'f'.

       $md6->b64digest

       Same as $md6->digest, but will return the digest as a
       base64 encoded string.  The length of the returned string
       will be 22 and it will only contain characters from this
       set: 'A'..'Z', 'a'..'z', '0'..'9', '+' and '/'.

       The base64 encoded string returned is not padded to be a
       multiple of 4 bytes long.  If you want interoperability
       with other base64 encoded md6 digests you might want to



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       append the string " == " to the result.

       Digest, Digest::MD2, Digest::MD5, Digest::SHA,
       Digest::HMAC

       <http://en.wikipedia.org/wiki/MD6>;

       <http://groups.csail.mit.edu/cis/md6/>;

AUTHOR
       Andy Armstrong  "<andyAThexten.net>"

LICENCE AND COPYRIGHT
       Copyright (c) 2009, Andy Armstrong "<andyAThexten.net>".

       This module is free software; you can redistribute it
       and/or modify it under the same terms as Perl itself. See
       perlartistic.

       Based on Digest::MD5 by Gisle Aas which carries this
       copyright notice:

         Copyright 1998-2003 Gisle Aas.
         Copyright 1995-1996 Neil Winton.
         Copyright 1991-1992 RSA Data Security, Inc.

       The MD6 implementation used is
       <http://groups.csail.mit.edu/cis/md6/code/md6_c_code-2009-04-15.zip>;
       which is

         Copyright (c) 2008 Ronald L. Rivest

       The MD6 code is licensed under the MIT license.
























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