Blowfish is a published algorithm written by Bruce Schneier Unlike IDEA or DES etc. there are no patent implications in using this algorithm. It uses anywhere between a 64 bit and a 448 bit key. The transform itself is fast and operates on a 64 bit block, and most of the calculation time is in initialising the context with the key data. The _PP name comes from the fact that this implementation is Pure Perl, and will not have any compatibility problems. WWW: http://search.cpan.org/dist/Crypt-Blowfish_PP/