Computer Security

Security and Encryption (from Yahoo!)

Beginners' Guide to Cryptography

International Cryptography

Computer Security in Open Systems by Danny Smith

Kerberos (from Yahoo!)

MIT Kerberos V4.10 Distribution

kclient

Bugtraq mailing list archives

Computer Security Information from the National Institutes of Health

RSA

CYPHERNET

Enhancing Security of Unix Systems

Unix Host and Network Security Tools

Secure Network Communications

Derrick Brashear's Pointers to Authentication Info

PGP

PGP In a Nutshell 2.5, by Jeremiah S.Junken

PGP Documentation

DES

The Sollentuna Effort to Crack DES

Net Abuse (SPAM)

The SANS Institute

CIAC - Computer Incident Advisory Capability

So you want to crack a computer? Rootshell has a lot to say about that