This book is a select collection of edited papers from the International Conference on Security of Information and Networks (SIN 2007) on the main theme of Information Assurance, Security, and Public Policy. SIN 2007 was hosted by the Eastern Mediterranean University in Gazimagusa, North Cyprus and co-organized by the Istanbul Technical University, Turkey. While SIN 2007 covered all areas of information and network security, the papers included here focused on the following topics: - cryptology: design and analysis of cryptographic algorithms, hardware and software implementations of cryptographic algorithms, and steganography; - network security: authentication, authorization and access control, privacy, intrusion detection, grid security, and mobile and personal area networks; - IT governance: information security management systems, risk and threat analysis, and information security policies. They represent an interesting mix of innovative academic research and experience reports from practitioners. This is further complemented by a number of invited papers providing excellent overviews: - Elisabeth Oswald, University of Bristol, Bristol, UK: Power Analysis Attack: A Very Brief Introduction; - Marc Joye, Thomson R&D, France: On White-Box Cryptography; - Bart Preneel, Katholieke Universiteit Leuven, Leuven, Belgium: Research Challenges in Cryptology; - Mehmet Ufuk Caglayan, Bogazici University, Turkey: Secure Routing in Ad Hoc Networks and Model Checking. The papers are organized in a logical sequence covering Ciphers; Mobile Agents & Networks; Access Control and Security Assurance; Attacks, Intrusion Detection, and Security Recommendations; and, Security Software, Performance, and Experience.