GNU Privacy Guard Guide

What is Gnu Privacy Guard?

Gnu Privacy Guard (GnuPG) is an open-source tool for secure, private communications.  It's based off of the Pretty Good Privacy software originally written by Phil Zimmerman (now owned by someone else).

GnuPG is an independent implementation of the OpenPGP standards, so you can use it to exchange encrypted messages with people using other OpenPGP implementations (e.g. Symantec's PGP).

GnuPG uses public-key cryptography so that users may communicate securely. In a public-key system, each user has a pair of keys consisting of a private key and a public key. A user's private key is kept secret; it need never be revealed. The public key may be given to anyone with whom the user wants to communicate. GnuPG uses a somewhat more sophisticated scheme in which a user has a primary keypair and then zero or more additional subordinate keypairs. The primary and subordinate keypairs are bundled to facilitate key management and the bundle can often be considered simply as one keypair.