GNU Privacy Guard (GnuPG or GPG) is a free software replacement for the Symantec's PGP cryptographic software suite. GnuPG is compliant with RFC 4880, which is the IETF standards track specification of OpenPGP. Modern versions of PGP and Veridis' Filecrypt are interoperable with GnuPG and other OpenPGP-compliant systems.
