The 19th Annual IFIP Working Group 11.3 Working Conference on Data and Applications Security was held August 7-10, 2005 at the University of C- necticut in Storrs, Connecticut. The objectives of the working conference were to discuss in depth the current state of the researchand practice in data and - plicationsecurity,enableparticipantstobene?tfrompersonalcontactwithother researchers and expand their knowledge, support the activities of the Working Group, and disseminate the research results. This volume contains the 24 papers that were presented at the working c- ference. These papers, which had been selected from 54 submissions, were rig- ously reviewed by the Working Group members. The volume is o?ered both to document progressand to provideresearcherswith a broadperspective of recent developments in data and application security. A special note of thanks goes to the many volunteers whose e?orts made the working conference a success. We wish to thank Divesh Srivastava for agreeing to deliver the invited talk, Carl Landwehr and David Spooner for organizing the panel, the authors for their worthy contributions, and the referees for their time and e?ort in reviewing the papers. We are grateful to T. C. Ting for serving as the General Chair, Steven Demurjian and Charles E. Phillips, Jr. for their hard work as Local Arrangements Chairs, and Pierangela Samarati, Working Group Chair, for managing the IFIP approval process. We would also like to acknowledge Sabrina De Capitani di Vimercati for managing the conference's Web site.