Welcome to the second volume of the Kluwer International Series on ADVANCES IN INFORMATION SECURITY. The goals of this series are, one, to establish the state of the art of and set the course for future research in information security and, two, to serve as a central reference and timely topics in information security research source for advanced and development. The scope of this series includes all aspects of com puter and network security and related areas such as fault tolerance and software assurance. ADVANCES IN INFORMATION SECURITY aims to publish thor ough and cohesive overviews of specific topics in information security, as well as works that are larger in scope or that contain more detailed background information than can be accommodated in shorter survey articles. The series also serves as a forum for topics that may not have reached a level of maturity to warrant a comprehensive textbook treat ment. The success of this series depends on contributions by researchers and developers such as yourself. If you have an idea for a book that is appro priate for this series, I encourage you to contact either the Acquisitions Editor for the series, Lance Wobus (lwobus@wkap.com), or myself, the Consulting Editor for the series (jajodia@gmu.edu). We would be happy about to discuss any potential projects with you. Additional information this series can be obtained from www.wkap.nljseries.htmjADIS.