OpenPGP is the most widely used email encryption standard in the world. It is based on PGP (Pretty Good Privacy) as originally developed by Phil Zimmermann. The OpenPGP protocol defines standard formats for encrypted messages, signatures, and certificates for exchanging public keys.
PGP & GPG is an easy-to read, informal tutorial for implementing electronic privacy on the cheap using the standard tools of the email privacy field - commercial PGP and non-commercial GnuPG (GPG). The book shows how to integrate these OpenPGP implementations into the most common email clients and how to use PGP and GPG in daily email correspondence to both send and receive encrypted email.
The PGP & GPG book is written for the moderately skilled computer user who is unfamiliar with public key cryptography but who is nevertheless interested in guarding their email privacy. Lucas's trademark informal and relaxed tone makes public key cryptography as simple and clear as possible, so that any reasonably savvy computer user can understand it.