PGP

Short for Pretty Good Privacy, PGP was freeware released in 1991 by Philip Zimmermann, PGP is a public-key authentication and encryption method based on the IDEA single-key and RSA public-key encryption algorithms. PGP is now a product of PGP Corporation and still widely used encryption tool. After its initial release the U.S. government files charges against Philip alleging he broke U.S. encryption laws. These charges were later dropped.