NAME Crypt::Twofish2 - Crypt::CBC compliant Twofish encryption module SYNOPSIS use Crypt::Twofish2; # keysize() is 32, but 24 and 16 are also possible # blocksize() is 16 $cipher = new Crypt::Twofish2 "a" x 32, Crypt::Twofish2::MODE_CBC; $crypted = $cipher->encrypt($plaintext); # - OR - $plaintext = $cipher->decrypt($crypted); DESCRIPTION This module implements thw twofish cipher in a less braindamaged (read: slow and ugly) way than the existing "Crypt::Twofish" module. Although it is "Crypt::CBC" compliant you usually gain nothing by using that module (except generality), since "Crypt::Twofish2" can work in either ECB or CBC mode. keysize Returns the keysize, which is 32 (bytes). The Twofish2 cipher actually supports keylengths of 16, 24 or 32 bytes, but there is no way to communicate this to "Crypt::CBC". blocksize The blocksize for Twofish2 is 16 bytes (128 bits), which is somewhat unique. It is also the reason I need this module myself ;) $cipher = new $key [, $mode] Create a new "Crypt::Twofish2" cipher object with the given key (which must be 128, 192 or 256 bits long). The additional "$mode" argument is the encryption mode, either "MODE_ECB" (electronic cookbook mode, the default), "MODE_CBC" (cipher block chaining, the same that "Crypt::CBC" does) or "MODE_CFB1" (1-bit cipher feedback mode). ECB mode is very insecure (read a book on cryptography if you don't know why!), so you should probably use CBC mode. CFB1 mode is not tested and is most probably broken, so do not try to use it. In ECB mode you can use the same cipher object to encrypt and decrypt data. However, every change of "direction" causes an internal reordering of key data, which is quite slow, so if you want ECB mode and encryption/decryption at the same time you should create two seperate "Crypt::Twofish2" objects with the same key. In CBC mode you have to use seperate objects for encryption/decryption in any case. The "MODE_*"-constants are not exported by this module, so you must specify them as "Crypt::Twofish2::MODE_CBC" etc. (sorry for that). $cipher->encrypt($data) Encrypt data. The size of "$data" must be a multiple of "blocksize" (16 bytes), otherwise this function will croak. Apart from that, it can be of (almost) any length. $cipher->decrypt($data) The pendant to "encrypt" in that it *de*crypts data again. SEE ALSO the Crypt::CBC manpage, the Crypt::Twofish manpage. BUGS Should EXPORT or EXPORT_OK the MODE constants. The testsuite does not check wether the encrypted valued are correct. There should be a way to access initial IV contents :( Although I tried to make the original twofish code portable, I can't say how much I did succeed. The code tries to be portable itself, and I hope I got the endianness issues right. The code is also copyright Counterpane Systems, no license accompanied it, so using it might actually be illegal ;) AUTHOR Marc Lehmann http://www.goof.com/pcg/marc/ The actualy twofish encryption is written in horribly microsoft'ish looking almost ansi-c by Doug Whiting.