http://www.rfc-editor.org/rfc/rfc3156.txt
RFC 3156: MIME Security with OpenPGP, M. Elkins, D. Del Torto, R. Levien, T. Roessler2001-08-01T23:00:00-00:00This document describes how the OpenPGP Message Format can be used to provide privacy and authentication using the Multipurpose Internet Mail Extensions (MIME) security content types described in RFC 1847. [STANDARDS-TRACK]