I think except the cryptography there is just trust calculations and encoding. These two articles describe trust in detail: https://www.linux.com/learn/pgp-we

I think except the cryptography there is just trust calculations and encoding. These two articles describe trust in detail: https://www.linux.com/learn/pgp-web-trust-core-concepts-behind-trusted-communication https://www.linux.com/learn/pgp-web-trust-core-concepts-behi... https://www.linuxfoundation.org/blog/pgp-web-of-trust-delegated-trust-and-keyservers/ https://www.linuxfoundation.org/blog/pgp-web-of-trust-delega... GPG esoteric options is also a good read: https://www.gnupg.org/documentation/manuals/gnupg/GPG-Esoteric-Options.html https://www.gnupg.org/documentation/manuals/gnupg/GPG-Esoter... Besides that... the RFC itself I suppose: https://tools.ietf.org/html/rfc4880 https://tools.ietf.org/html/rfc4880