http://www.rfc-editor.org/rfc/rfc2312.txt
RFC 2312: S/MIME Version 2 Certificate Handling, S. Dusse, P. Hoffman, B. Ramsdell, J. Weinstein1998-03-01T23:00:00-00:00This memo describes the mechanisms S/MIME uses to create and validate keys using certificates. This memo provides information for the Internet community. It does not specify an Internet standard of any kind.