=head1 NAME
DES - Perl interface to DES block cipher
=head1 SYNOPSIS
use Crypt::DES;
=head1 DESCRIPTION
This perl extension is an implementation of the DES block cipher algorithm.
The module implements the Crypt::BlockCipher interface,
which has the following methods
=over 4
=item blocksize
=item keysize
=item encrypt
=item decrypt
=back
=head1 FUNCTIONS
=over 4
=item blocksize
Returns the size (in bytes) of the block cipher.
=item keysize
Returns the size (in bytes) of the key.
=item new
my $cipher = new DES $key;
This creates a new DES BlockCipher object, using $key,
where $key is a key of C<keysize()> bytes.
=item encrypt
my $cipher = new DES $key;
my $ciphertext = $cipher->encrypt($plaintext);
This function encrypts $plaintext and returns the $ciphertext
where $plaintext and $ciphertext should be of C<blocksize()> bytes.
=item decrypt
my $cipher = new DES $key;
my $plaintext = $cipher->decrypt($ciphertext);
This function decrypts $ciphertext and returns the $plaintext
where $plaintext and $ciphertext should be of C<blocksize()> bytes.
=back
=head1 EXAMPLE
my $key = pack("H16", "0123456789ABCDEF");
my $cipher = new DES $key;
my $ciphertext = $cipher->encrypt("plaintex"); # NB - 8 bytes
print unpack("H16", $ciphertext), "\n";
=head1 SEE ALSO
Crypt::IDEA
Bruce Schneier, I<Applied Cryptography>, 1995, Second Edition,
published by John Wiley & Sons, Inc.
=head1 COPYRIGHT
The implementation of the DES algorithm was developed by,
and is copyright of, Eric Young (eay@mincom.oz.au).
Other parts of this perl extension are
copyright of Systemics Ltd ( http://www.systemics.com/ ).