Computer Security in the 21st Century shares some important research trends reflected in the emergence of the latest advances in computer security, including: security protocol design, secure peer-to-peer and ad hoc networking, multimedia security, and intrusion detection, defense and measurement. Highlights include presentations from: -Fundamental new security Cryptographic-protocol and design, -A new way of measuring network vulnerability: attack surfaces, Network vulnerabilities and construct-impenetrable system, -Multimedia content protection including a new standard for photographic images, JPEG2000.