This is a S/MIME interface for Emacs. It uses, and requires, OpenSSL 0.9.6 or later. There are some usage instructions in the comment section of the code.
As of October 2000, and when used together with dig.el, this library is capable of retrieving S/MIME certificates from DNS, using the DNS CERT RR. It uses the standard SOA translation of e-mail addresses into domain names.
The code is available from here, and is inlined below.
It was developed as part of my Master Thesis work.
The Gnus integration is included in Oort Gnus, and is distributed via the Gnus tower.