Some files have a (separate) PGP signature to protect you against trojanized versions.
This is my PGP public key. You can reach me personally as email@example.com
TCT is a collection of programs that can be used for a post-mortem analysis of a UNIX system after break-in. The software was presented first during a free Computer Forensics Analysis class in August 1999.
Postfix attempts to be fast, easy to administer, and secure, while at the same time being sendmail compatible enough to not upset existing users. Thus, the outside has a sendmail-ish flavor, but the inside is completely different.
This software was formerly known as VMailer. It was released by the end of 1998 as the IBM Secure Mailer. From then on it has lived on as Postfix.
See hints-and-tips.html if you have trouble compiling or configuring the software.
The paper also announces a piece of security software called SATAN (Security Administrator Tool for Analyzing Networks). It took the authors more than a year to fulfill their promise.