5th CCS 1998 Message from the Program Chair The 17 papers in this proceedings were presented at the 5th ACM Conference on Computer and Communications Security, held in San Francisco, California, on November 2-5, 1998. These papers document important advances in the design, analysis, and implementation of secure computer and communication systems, as determined by an international program committee of experts in this field. These papers were selected from 85 submissions-an all-time high for the conferences in this series-yielding a very competitive 20% rate of acceptance. Papers were submitted from institutions in 18 countries on four continents. Each submission was reviewed by at least three members of the program committee (or their delegates), and typically four or more. As in previous years, the review process was "double-blind": program committee members were not informed of the authors of submitted papers or their institutions, and similarly authors were not informed of who reviewed their papers. I hope that this helped to achieve an objective review process. The final selection of papers took place during a meeting of the program committee at AT&T Labs in Florham Park, NJ, USA on May 29, 1998. The program committee also participated in the selection of other conference events, including a panel session moderated by Paul Syverson; invited lectures by Martin Hellman, Peter Neumann, and Fred Schneider; and tutorials by Martin Abadi, Dan Boneh, Jonathan Millen, George Necula, and Doug Tygar. I am very grateful to Martin Abadi, Bill Cheswick, Carl Ellison, Ed Felten, Paul Karger, Stephen Kent, Ueli Maurer, Catherine Meadows, David Naceache, Hilarie Orman, Avi Rubin, Pierangela Samarati, Gene Tsudik, Paul Van Oorschot, Bennet Yee, and Moti Yung, for their service as members of the program committee. I would also like to thank others to whom program committee members delegated reviews: Giuseppe Ateniese, Jan Camenisch, Ronald Cramer, Drew Dean, Grit Denker, Serge Fehr, Matthias Fitzi, Yair Frankel, Matt Franklin, Stephen Freund, Pierre Girard, Helena Handschuh, Markus Jakobsson, Olaf Keller, Reto Kohlas, Gary McGraw, David M'Raihi, Phong Nguyen, Pascal Paillier, Larry Paulson, Phil Porras, Dave Presotto, Emilia Rosti, Ludovic Rousseau, Richard Schroeppel, Paul Syverson, Yiannis Tsiounis, Serge Vaudenay, Giovanni Vigna, and Stefan Wolf. I am deeply grateful to Li Gong, the conference General Chair, and Ravi Sandhu, the conference Steering Committee Chair, for their support and suggestions. Last but not least, I thank the authors of all submitted papers for supporting this conference with their submissions. I believe that this year's program bolsters the tradition of research excellence that is characteristic of this conference series. I am grateful for the opportunity to be affiliated with it. Michael K. Reiter Program Chair, 5th ACM Conference on Computer and Communications Security