Digest::BubbleBabble - Create bubble-babble fingerprints


Digest-BubbleBabble documentation Contained in the Digest-BubbleBabble distribution.

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NAME

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Digest::BubbleBabble - Create bubble-babble fingerprints

SYNOPSIS

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    # Create a fingerprint of a simple string.
    use Digest::BubbleBabble qw( bubblebabble );
    my $fingerprint = bubblebabble( Digest => "Pineapple" );

    # Create a fingerprint of a SHA-1 hash.
    use Digest::SHA1 qw( sha1 );
    $fingerprint = bubblebabble( Digest => sha1("hello") );

DESCRIPTION

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Digest::BubbleBabble takes a message digest (often generated by either of the MD5 or SHA-1 message digest algorithms) and creates a fingerprint of that digest in "bubble babble" format. Bubble babble is a method of representing a message digest as a string of "real" words, to make the fingerprint easier to remember. The "words" are not necessarily real words, but they look more like words than a string of hex characters.

Bubble babble fingerprinting is used by the SSH2 suite (and, consequently, by Net::SSH::Perl, the Perl SSH implementation) to display easy-to-remember key fingerprints. The key (a DSA or RSA key) is converted into a textual form, digested using Digest::SHA1, and run through bubblebabble to create the key fingerprint.

USAGE

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Digest::BubbleBabble conditionally exports one function called bubblebabble; to import the function you must choose to import it, like this:

    use Digest::BubbleBabble qw( bubblebabble );

bubblebabble( Digest => $digest )

Currently takes only one pair of arguments, the key of which must be Digest, the value of which is the actual message digest $digest. You should generate this message digest yourself using either Digest::MD5 of Digest::SHA1.

Returns the bubble babble form of the digest.

SEE ALSO

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The BubbleBabble specification is available at: http://web.mit.edu/kenta/www/one/bubblebabble/spec/jrtrjwzi/draft-huima-01.txt

LICENSE

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Digest::BubbleBabble is free software; you may redistribute it and/or modify it under the same terms as Perl itself.

AUTHOR & COPYRIGHTS

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Benjamin Trott, cpan@stupidfool.org

Except where otherwise noted, Digest::BubbleBabble is Copyright 2001 Benjamin Trott. All rights reserved.


Digest-BubbleBabble documentation Contained in the Digest-BubbleBabble distribution.

package Digest::BubbleBabble;
use strict;
use 5.008_001;

use Exporter;
use vars qw( @EXPORT_OK @ISA $VERSION );
@ISA = qw( Exporter );
@EXPORT_OK = qw( bubblebabble );

$VERSION = '0.02';

use vars qw( @VOWELS @CONSONANTS );
@VOWELS = qw( a e i o u y );
@CONSONANTS = qw( b c d f g h k l m n p r s t v z x );

sub bubblebabble {
    my %param = @_;
    my @dgst = map ord, split //, $param{Digest};
    my $dlen = length $param{Digest};

    my $seed = 1;
    my $rounds = int($dlen / 2) + 1;
    my $retval = 'x';
    for my $i (0..$rounds-1) {
        if ($i+1 < $rounds || $dlen % 2) {
            my $idx0 = ((($dgst[2 * $i] >> 6) & 3) + $seed) % 6;
            my $idx1 = ($dgst[2 * $i] >> 2) & 15;
            my $idx2 = (($dgst[2 * $i] & 3) + $seed / 6) % 6;
            $retval .= $VOWELS[$idx0] . $CONSONANTS[$idx1] . $VOWELS[$idx2];
            if ($i+1 < $rounds) {
                my $idx3 = ($dgst[2 * $i + 1] >> 4) & 15;
                my $idx4 = $dgst[2 * $i + 1] & 15;
                $retval .= $CONSONANTS[$idx3] . '-' . $CONSONANTS[$idx4];
                $seed = ($seed * 5 + $dgst[2 * $i] * 7 +
                        $dgst[2 * $i + 1]) % 36;
            }
        }
        else {
            my $idx0 = $seed % 6;
            my $idx1 = 16;
            my $idx2 = $seed / 6;
            $retval .= $VOWELS[$idx0] . $CONSONANTS[$idx1] . $VOWELS[$idx2];
        }
    }
    $retval .= 'x';
    $retval;
}

1;
__END__