The increasing relevance of security to real-life applications, such as electronic commerce, is attested by the fast-growing number of research groups, events, conferences, and summer schools that are studying it. This book presents thoroughly revised versions of eight tutorial lectures given by leading researchers during two International Schools on Foundations of Security Analysis and Design, FOSAD 2006/2007, held in Bertinoro, Italy, in September 2006 and September 2007.