GnuPG (the GNU Privacy Guard or GPG) is GNU's tool for secure communication and data storage. It can be used to encrypt data and to create digital signatures. It includes an advanced key management facility and is compliant with the proposed OpenPGP Internet standard as described in RFC2440. As such, it is meant to be compatible with PGP from NAI, Inc. Because it does not use any patented algorithms, it can be used without any restrictions.
Read more https://packetstormsecurity.com/files/158375/gnupg-2.2.21.tar.bz2