Information assurance and security has become an important research issue in the networked and distributed information sharing environments. Finding effective ways to protect information systems, networks and sensitive data within the critical information infrastructure is challenging even with the most advanced technology and trained professionals. The International Conference on Information Assurance and Security (IAS) aims to bring together researchers, practitioners, developers, and policy makers involved in multiple disciplines of information security and assurance to exchange ideas and to learn the latest development in this important field. The proceedings of IAS09 will be published by IEEE Computer Society and will be indexed by EI and ISTP.