OpenPGP

OpenPGP is the most widely used email encryption standard. It is defined by the OpenPGP Working Group of the Internet Engineering Task Force (IETF) as a Proposed Standard in RFC 4880. OpenPGP was originally derived from the software, created by Phil Zimmermann.

OpenPGP is a non-proprietary protocol for encrypting email communication using public key cryptography. The OpenPGP protocol defines standard formats for encrypted messages, signatures, and certificates for exchanging public keys.

Beginning in 1997, the OpenPGP Working Group was formed in the Internet Engineering Task Force (IETF) to define this standard that had formerly been a proprietary product since 1991. Over the past decade, PGP, and later OpenPGP, has become the standard for nearly all of the world’s encrypted email.

As an IETF Proposed Standard RFC 4880, OpenPGP can be implemented by any company without paying any licensing fees to anyone.