Pretty Good Privacy (PGP)

A public/private key system that uses the IDEA algorithm to encrypt files and email messages. PGP is not a standard but rather an independently developed product that has wide Internet grassroots support. See also GNU Privacy Guard (GnuPG). PGP provides confidentiality and authentication services for electronic mail and file storage applications. Developed by Phil Zimmerman and distributed for free on the Internet. Widely used by the Internet technical community.