EntourageGPG 1.2 (Mac)

EntourageGPG allows encryption of your email in a way that only the person you intend to read it can, and also allows "signing" of those messages, verifying your identity. GNU Privacy Guard (GPG), and all Pretty Good Privacy (PGP) implementations, use public key encryption. With public key encryption, it isn't required that the recipient of your message have a previously established password or secret. Instead, you encrypt a message with their freely-available public key, then they decrypt it with their private or secret key, which only they have access to. The mathematics behind this are very hard to explain, but suffice to say that it is very unlikely that anyone would be able to decrypt your message. Signing consists of the same thing in reverse; a "hash", or compressed version, of your message is signed with your private key, then that hash can be decrypted by anyone with your public key and it can be verified that the message has not been modified and it is indeed yours.