The Data Encryption Standard (DES), also known as Data
Encryption Algorithm (DEA) is a semi-strong encryption and
decryption algorithm.
The module is 100 % compatible to Crypt::DES but is implemented
entirely in Perl. That means that you do not need a C compiler
to build and install this extension.
The module implements the Crypt::CBC interface. You are
encouraged to read the documentation for Crypt::CBC if you
intend to use this module for Cipher Block Chaining.
The minimum (and maximum) key size is 8 bytes. Shorter keys will
cause an exception, longer keys will get silently truncated.
Data is encrypted and decrypted in blocks of 8 bytes.
The module implements the Ultra-Fast-Crypt (UFC) algorithm as
found for example in the GNU libc. On the Perl side a lot has
been done in order to make the module as fast as possible
(function inlining, use integer, ...).
Note: For performance issues the source code for the module is
first preprocessed by m4. That means that you need an m4 macro
processor in order to hack on the sources. This is of no concern
for you if you only want to use the module, the preprocessed
output is always included in the distribution.

WWW: http://search.cpan.org/dist/Crypt-DES_PP/