Blowfish encryption algorithm implemented purely in Perl The Crypt::Blowfish_PP module provides for users to use the Blowfish encryption algorithm in perl. The implementation is entirely Object Oriented, as there is quite a lot of context inherent in making blowfish as fast as it is. The key is anywhere between 64 and 448 bits (8 and 56 bytes), and should be passed as a packed string. The transformation itself is a 16-round Feistel Network, and operates on a 64 bit block.