NAME

Crypt::Shark - Crypt::CBC compliant block cipher

ABSTRACT

Shark is 64-bit block cipher that accepts a 128-bit key.

SYNOPSIS

    use Crypt::Shark;
    $cipher = new Crypt::Shark $key;
    $ciphertext = $cipher->encrypt($plaintext);
    $plaintext  = $cipher->decrypt($ciphertext);

DESCRIPTION

Shark is 64-bit block cipher that accepts a 128-bit key. It was designed by Vincent Rijmen, Joan Daemen, Bart Preneel, Antoon Bosselaers, and Erik De Win.

This module supports the Crypt::CBC interface, with the following functions.

Functions

blocksize: Returns the size (in bytes) of the block (8, in this case).
keysize: Returns the size (in bytes) of the key (16, in this case).
encrypt($data): Encrypts 8 bytes of $data and returns the corresponding ciphertext.
decrypt($data): Decrypts 8 bytes of $data and returns the corresponding plaintext.

EXAMPLE 1

    #!/usr/local/bin/perl
    use diagnostics;
    use strict;
    use warnings;
    use Crypt::Shark;
    # key must be 16 bytes long
    my $key = "0123456789abcdef";
    my $cipher = new Crypt::Shark $key;
    print "blocksize = ", $cipher->blocksize, " bytes \n";
    print "keysize = ", $cipher->keysize, " bytes \n";
    # block must be 8 bytes long
    my $plaintext1 = "01234567";
    my $ciphertext = $cipher->encrypt($plaintext1);
    my $plaintext2 = $cipher->decrypt($ciphertext);
    print "Decryption OK\n" if ($plaintext1 eq $plaintext2);

EXAMPLE 2

    #!/usr/local/bin/perl
    use diagnostics;
    use strict;
    use warnings;
    use Crypt::CBC;  # CBC automatically loads Shark for us
    # when using Crypt::CBC, key may be of ANY length
    my $key = "0123456789abcdef";
    # IV must be exactly 16 bytes long
    my $IV = pack "H16", 0;
    my $cipher = Crypt::CBC->new({'key' => $key,
                                  'cipher' => 'Shark',
                                  'iv' => $IV,
                                  'regenerate_key' => 1,
                                  'padding' => 'standard',
                                  'prepend_iv' => 0
                                });
    # when using Crypt::CBC, plaintext may be of ANY length
    my $plaintext1 = "This is a test";
    my $ciphertext = $cipher->encrypt($plaintext1);
    my $plaintext2 = $cipher->decrypt($ciphertext);
    print "Decryption OK\n" if ($plaintext1 eq $plaintext2);

MORE EXAMPLES

See Crypt::CBC for more examples using CBC mode. See also the "examples" and "t" directories for some more examples.

COPYRIGHT AND LICENSE

This library is free software; you can redistribute it and/or modify it under the same terms as the GNU General Public License.