An index of web-pages of interest to people involved with cryptography and security research - lots of information here!
An introductory course in Computer Security (Technion, Israel) - useful background reading around the subject.
Confidentiality, Integrity, Availability - a nice quick overview of what it means and how it applies in Security Analysis
Set of slides on an introduction to Buffer Overflows and similar security attacks - nice clear diagrams... not too much detail
Improving the Security of Your Site by Breaking Into it - does exactly what it says... quite difficult stuff about real methods used
Tuomas Aura's Homepage (until December 2000) - lots of interesting and specific articles, but quite a difficult read