uh, in other news, this same topic is appearing on perl.com : ciphers and perl.
Interestingly, all of this hoohah may be reduced to

use Crypt::CBC;
$cipher = new Crypt::CBC ($key, 'Twofish');
undef $/; $plaintext = <PLAINTEXT>;
print CIPHERTEXT $cipher->encrypt($plaintext);
[download]

I think that cryptography will join CGI as "modules to not reinvent" as far as I'm concerned.