4.6.4 PGP and GPG, Key-pair System

PGP is Pretty Good Privacy. GPG is GNU Privacy Guard. Both consist of a suite of programs that ensures the privacy and security of content transmission over the Internet (or data in storage).

Fundamental to both systems is the key-pair concept. Let's worry about the mechanism of the key-pair system later. Right now, let's focus on the application of PGP or GPG.

GPG can encrypt messages. This means a message can only be viewed by its intended recipient. This is important, because it means an ISP can no longer understand a message in transit.

GPG can also sign messages. This means a message can be digitally signed so that the recipient can authenticate the origin of a message. Both plain and encrypted messages can be signed.

Thunderbird has extensions to integrate GPG nicely into the email client. It can encrypt, decipher, sign and authenticate messages conveniently. Furthermore, the GPG extension can also maintain key-rings, so that you don't have to manually track the public keys of recipients.