NAME

MAD::Scrambler - Scramble nibbles of a 32-bit integer

VERSION

version 0.000005

SYNOPSIS

Scrambles a 32-bit integer with a kind of reversible hashing function. Definitely it is not a cryptographic hash, it is just of reversible shuffle.

    use MAD::Scramble;

    my $scrambler = MAD::Scrambler->new(
        scrambler => [ 1, 3, 5, 7, 0, 2, 4, 6 ],
        bit_mask  => 0xFDB97531,
    );

    my $code = $scrambler->encode( 42 );
    ## 0xFDB37533

    my $number = $scrambler->decode( 0xFDB37533 );
    ## 42

Very useful for example when you need to expose a reference to a object into a database in a URL, but you don't want expose the original data.

Note that this is not for solving security problems, sure, since this is reversible and someone can extract back the original value.

Think in this approach when you want difficult the guess of the value instead of completely forbid the access to it.

METHODS

new( %args )

Constructor.

%args is a hash which may contains the keys scrambler and bit_mask.

scrambler is the order to "shuffle" the nibbles of the number you will encode. Internally an "unscrambler" is calculated to reverse de process when you decode a previously encoded number.

bit_mask is a 32-bit value to be "XORed" with the new scrambled number when encoding or decoding.

If any argument is not supplied, it will be randomly generated.

encode( $number )

Scrambles a number into a different one based on the attributes scrambler and bit_mask.

decode( $code )

Reverses the encoding made by encode.

nibble_split( $number )

Splits apart the given number in eight nibbles. The least significant nibbles are put in the lowest indexes.

    use MAD::Scrambler qw{ nibble_split };

    @nibbles = nibble_split( 0x12345678 );
    ## ( 8, 7, 6, 5, 4, 3, 2, 1 )

nibble_join( @nibbles )

Joins the nibbles together returning the corresponding integer. The least significant nibbles are located in the lowest indexes.

    use MAD::Scrambler qw{ nibble_join };

    my $number = nibble_join( 1, 3, 5, 7, 9, 11, 13, 15 )
    ## 0xFDB97531

AUTHOR

Blabos de Blebe <blabos@cpan.org>

COPYRIGHT AND LICENSE

This software is copyright (c) 2014 by Blabos de Blebe.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.