OpenPGP Library for .NET includes methods for OpenPGP encryption, decryption, clear signing, one pass sign and encrypt, decrypt and verify, key generation, supports both key store and keys located in files. Entirely written in managed code, there are no external third party dependencies.
PGP tutorial Is a Free (open-source) implementation of the OpenPGP standard. Interoperates with PGP 2.x and 5.x. This tutorial will cover gpg. Concepts will apply to PGP versions, but all the commands are gpg-specific. Making a key. First, install gpg. Package in Debian is named gnupg. The Difference Between PGP, OpenPGP, and GnuPG Encryption
gnupg - How do you use the PHP OpenPGP library? - Stack