A new model of security for distributed systems

With the rapid growth of the information age, open distributed systems have become increasingly popular.The need for protection and security in a distributed environment has never been greater.The conventional approach to security has been to enforce a system-wide policy, but this approach will not work for large distributed systems where entirely new security issues and concerns are emerging.We argue that a new model is needed that shifts the emphasis from "system as enforcer" to user-definable policies.Users ought to be able to select the level of security they need and pay only the necessary overhead.Moreover.ultimately, they must be responsible for their own security.This research is being carried out in the context of the Legion project.We start by describing the objectives and philosophy of the overall project and then present our conceptual model and design decisions.A set of technical challenges and related issues are also addressed.