4th CCS 1997 Program Chairs' Foreword As program chairs for the 4tli ACM Conference on Computer and Communications Security we would like to welcome you. In the past three years, this conference has established itself as a forum at which research in a computer security disciplines come together to interact with with colleagues working in the area. The selection process for the conference papers was extremely rigorous. We received 64 submissions, and each was sent to three members of the program committee for review. Some of these reviews were delegated by program committee members to external reviewers. The author's identity was hidden from reviewers during the review process. In October the program committee was assembled for a day long meeting at JavaSoft in Cupertino. The committee deliberated and selected the papers that appear in the program. This year we accepted 17 papers into a program that we are sure you will find interesting. The number of papers finally accepted is consistent with the highly selective standards established by the previous conferences, and it allows time for two panels on the topics of programming languages as a basis for security and persistence of digital signatures. Furthermore, we have been careful to leave enough time for discussions between participants. The success of any conference depends on the quality of the submitted papers, on the efforts of the reviewers to select the best of those papers, and on the reviewer's ability to provide feedback to the authors to improve the papers. It would not be possible for us to put together such a good program without the authors and the reviewers. We would like to thank the program committee members, the external reviewers, the conference organizing committee, and everyone that submitted a paper, whether accepted or not, for their contribution to the conference. Finally, this is the first year that we are offering tutorials as part of the conference program. The organization of the tutorials was almost entirely the effort of Harry Rudin and Phil Janson, and we thank them for the significant effort made to line up and coordinate the tutorials. Clifford Neuman Marina del Rey, California USA 15 December 1996 Li Gong Cupertino, California USA 15 December 1996