GnuPG is a complete and free replacement for PGP. Because it does not use the patented IDEA algorithm, it can be used without any restrictions. GnuPG is a RFC2440 (OpenPGP) compliant application.
*** version 1.4.5 is now available ***
GnuPG Made Easy (GPGME) is a library designed to make access to GnuPG easier for applications. It provides a High-Level Crypto API for encryption, decryption, signing, signature verification and key management. Currently it uses GnuPG as its backend but the API isn't restricted to this engine; in fact we have already developed a backend for CMS (S/MIME).