Security is a rapidly growing area of computer science, with direct and increasing relevance to real-life applications, such as Internet transactions, e-commerce, information protection, network and systems security, etc. Foundations for the analysis and design of security features of such applications are badly needed in order to validate and prove their correctness. This book presents thoroughly revised versions of six tutorial lectures given by leading researchers during two International Schools on Foundations of Security Analysis and Design, FOSAD 2001/2002, held in Bertinoro, Italy, in September 2001 and September 2002. The lectures are devoted to: - Formal Approaches to Approximating Noninterference Properties - The Key Establishment Problem - Name-Passing Calculi and Cryptoprimitives - Classification of Security Properties; Network Security - Cryptographic Algorithms for Multimedia Traffic - Security for Mobility