This text provides the professional IT community and, in particular, security and data protection experts and researchers, with state-of-the-art material on emerging technologies for IT security and privacy issues. Furthermore, the book analyses the security threats and vulnerabilities that appear in modern information societies. The book covers issues related to security and privacy of information in a wide range of applications, including: secure networks and distributed systems; secure multicast communication and secure mobile networks; intrusion prevention and detection; access control policies and models; security protocols; security and control of IT in society. This volume contains the papers selected for presentation at the 18th International Conference on Information Security (SEC2003) and at the associated workshops. The conference and workshops were sponsored by the International Federation for Information Processing (IFIP) and held in Athens, Greece in May 2003.