OpenPGP

Five people and (people from) three orgs with(?) the IETF specced the OpenPGP message format in RFC 4880. PGP means ‘Pretty Good Privacy’. They specced OpenPGP as an interface for encrypting and decrypting data packets with separate-but-referenced(?) public(?) key packets. Gnu Privacy Guard (GPG), used by APT and Git, implements against this interface.