The GNU Privacy Guard (a.k.a. GnuPG, or simply gpg) is a free software implementation of Philip Zimmermann’s notorious, powerful, and popular program PGP (Pretty Good Privacy).
GnuPG is cooler than a secret decoder ring, so get out of that GUI recliner for a few minutes and come learn a couple of secret spy crypto command-line tricks.
GnuPG has two main uses. The first is to encrypt and decrypt data to ensure its privacy. The second is to “sign” data so that others can determine it is authentic and unmodified.
GnuPG is widely used, so it is included as standard fare in most modern distributions. If it didn’t come with yours, you can download source code or binary versions from the GnuPG website at the following URL: