gpg:
[GNU Privacy Guard](https://gnupg.org/) (GnuPG) is a cryptography suite. It implements a combination of conventional symmetric-key cryptography for speed, and public-key cryptography for ease of secure key exchange. GnuPG is the GNU project's complete and free implementation of the OpenPGP standard as defined by [RFC4880](https://www.ietf.org/rfc/rfc4880.txt).