Crypt::RSA is a pure-perl, cleanroom implementation of the RSA public-key 
cryptosystem. It uses Math::Pari, a perl interface to the blazingly fast 
PARI library, for big integer arithmetic and number theoretic computations.

Crypt::RSA provides arbitrary size key-pair generation, plaintext-aware 
encryption (OAEP) and digital signatures with appendix (PSS). For 
compatibility with SSLv3, RSAREF2, PGP and other applications that follow 
the PKCS #1 v1.5 standard, it also provides PKCS #1 v1.5 encryption and 
signatures.
