S/MIME message signing, verification, encryption and decryption module

 Crypt::SMIME provides a class for handling S/MIME messages. It can sign,
 verify, encrypt and decrypt messages.
 .
 Crypt::SMIME operates on email messages as simple strings, so there's no
 particular integration with other MAIL::* or MIME::* modules. Rather, it
 can co-operate with any module capable of accepting / outputting the entire
 message as a single string.