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

Security is a rapidly growing area of computer science, with direct and increasing relevance to real life applications such as Internet transactions, electronic commerce, information protection, network and systems integrity, etc. This volume presents thoroughly revised versions of lectures given by leading security researchers during the IFIP WG 1.7 International School on Foundations of Security Analysis and Design, FOSAD 2000, held in Bertinoro, Italy in September. Mathematical Models of Computer Security (Peter Y.A. Ryan); The Logic of Authentication Protocols (Paul Syversen and Iliano Cervesato); Access Control: Policies, Models, and Mechanisms (Pierangela Samarati and Sabrina de Capitani di Vimercati); Security Goals: Packet Trajectories and Strand Spaces (Joshua D. Guttman); Notes on Nominal Calculi for Security and Mobility (Andrew D. Gordon); Classification of Security Properties (Riccardo Focardi and Roberto Gorrieri).

This book constitutes the refereed proceedings of the 4th International Conference on Principles of Security and Trust, POST 2015, held as part of the European Joint Conferences on Theory and Practice of Software, ETAPS 2015, in London, UK, in April 2015. The 17 regular papers presented in this volume were carefully reviewed and selected from 57 submissions. In addition, one invited talk is included. The papers have been organized in topical sections on information flow and security types, risk assessment and security policies, protocols, hardware and physical security and privacy and voting.