=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/ ).
