PGP

Pretty Good Privacy is a flavor of algorithmic encryption that uses two cipher keys, one public and one private. Anyone can use a public key to send a scrambled message to the receiving party. The private key is then used only by the receiving party to unscramble incoming messages. The two-key system was developed by RSA Data Security, Inc. and PGP is the most popular type of two-key encryption available for public, non-commercial use.