7th CCS 2000 Message from the General Chair It is my great honor and privilege to welcome to Athens all of you distinguished guests and participants to the 7h ACM Computer and Communications Security Conference (CCS-2000). After a series of six successful CCS conferences, the ACM SIGSAC - through its Steering Committee Chair, Ravi Sandhu - agreed that the seventh conference in the series be held in Athens, Greece. The Conference Committees did their best to bring together the research communities of industry and academia, from all over the world. We trust that the conference will result in considerable stimulus for further research, application, and training and education in computer and communications security. It is clear - in the Information era - that no effective solution can be given, to any problem, without first putting this problem into its social context. Having this in mind, the conference organizers tried to establish a forum from a global secure information infrastructure perspective. New technology applications are developed because of mankind, by mankind, for mankind. Therefore, mankind should be the focus of the attention and its happiness should be the ultimate purpose of our efforts. The Conference was put together with the support of several people and organizations. To begin with, the Conference is sponsored by ACM SIGSAC and hosted by the Athens Chamber of Commerce and Industry (ACCI). The Athens University of Economics and Business (AUEB), the Greek Computer Society (GCS) and the Center for Secure Information Systems (George Mason University, USA) served, also, as co-organizers. A number of organizations, namely, Ernst & Young (GR), Citibank (GR), Space Hellas (GR), Instant Lottery (GR), CheckFree (USA), and Intracom (GR), kindly served as supporters of the Conference. We are most grateful to all of the above for their continuous support and encouragement. I would like, also, to express my appreciation to the members of the Organizing Committee, namely, N. Kyrloglou (ACCI), S. Gritzalis (GCS), S. Kokolakis (AUEB), K. Moulinos (Data Protection Authority), T. Tryfonas (AUEB), V. Tsoumas (Ernst &Young) and M. Karyda (AUEB). There would be no conference without them. The success of any conference depends heavily on the quality of the selected papers. For selecting the best out of many excellent submitted papers, we are indebted to Sushil Jajodia, our Program Committee Chair, and to the members of the Program Committee. Finally, no Conference can ever take place without the support of those individuals who submit their original research results, or without the participants, who honor the conference with their presence. Enjoy the conference and have a great time in Athens, the city with which History, Philosophy and Art are synonymous! Ass. Prof. Dr. Dimitris Gritzalis CCS-2000 General Chair Dept. of Informatics Athens University of Economics & Business