GnuPG is GNU's tool for secure communication and data storage.
It can be used to encrypt data and to create digital signatures.
It includes an advanced key management facility and is compliant with the proposed OpenPGP Internet standard as described in RFC2440 and the S/MIME standard as described by several RFCs. GnuPG2 is a newer version of GnuPG with additional support for S/MIME.
It has a different design philosophy that splits functionality up into several modules. This package includes support for smart cards and S/MIME encryption and signing.