Preface Formal Aspects of Security (FASec) was held at Royal Holloway, University of London, 18–20 December 2002. The occasion celebrated a Jubilee, namely the 25thanniversaryoftheestablishmentofBCS-FACS,theFormalAspectsofC- puting Science specialist group of the British Computer Society. FASec is one of a series of events organized by BCS-FACS to highlight the use of formal me- ods, emphasize their relevance to modern computing, and promote their wider application. As the architecture model of information systems evolves from - connected PCs,throughintranet (LAN) and internet (WAN), to mobile internet and grids, security becomes increasingly critical to all walks of society: c- merce, ?nance, health, transport, defence and science. It is no surprise therefore that security is one of the fastest-growing research areas in computer science. Theaudience ofFASec includes thosein the formalmethods community who have(orwouldliketodevelop)adeeper interestinsecurity,andthoseinsecurity who would like to understand how formal methods can make important cont- butions to some aspects of security. The scope of FASec is deliberately broad andcoverstopics that rangefrommodelling securityrequirementsthroughsp- i?cation, analysis, and veri?cations of cryptographic protocols to certi?ed code. The discussions at FASec 2002 encompassed many aspects of security: from theoretical foundations through support tools and on to applications. Formal methods has made a substantial contribution to this exciting ?eld in the past.