Practical Internet Groupware

Email: Encryption and Authentication

A series that begins with RFC1040 (January 1988, Privacy Enhancement for Internet Electronic Mail: Part I—Message Encipherment and Authentication Procedures) and culminates in RFC1421 (February 1993, same title) defines protocol extensions and processing procedures used to encrypt and authenticate RFC822 messages. The base64 encoding scheme, used in many Internet protocols to represent binary data using printable ASCII characters, is defined here.

RFC1114 (August 1989, Privacy Enhancement for Internet Electronic Mail: Part II—Certificate-Based Key Management), superseded by RFC1422 (February 1993, same title) defines a public-key infrastructure that supports message encryption and authentication. It does so by interpreting the CCITT 1988 Recommendation X.509 certificate mechanism “to serve the needs of privacy-enhanced mail in the Internet environment.”

I sign all my email messages, and when I do they carry the Multipart/Signed Content-Type: header defined in RFC1847 (October 1995, Security Multiparts for MIME: Multipart/Signed and Multipart/Encrypted).

RFC1991 (August 1996, PGP Message Exchange Formats) describes the use of PGP to encrypt and authenticate messages. RFC2015 (October 1996, MIME Security with Pretty Good Privacy (PGP)) defines the MIME content types application/pgp-encrypted, application/pgp-signature and application/pgp-keys. It specifies how to use MIME to format messages that are signed and/or encrypted using PGP.

A set of documents ...