Advice from Belnap Policies

Coordination languages for mobile, distributed systems constitute a good basis for the use of aspect-oriented features for providing a clear separation between the functionality and the security policies of programs. Allowing for a distributed definition of aspects, that jointly define a security policy, provide for a number of challenges regarding how to deal with conflicts and how to demonstrate that an overall security policy is met. We adapt recent work on policy composition using Belnap Logic to provide a uniform treatment of conflicts. We further define a modal logic to allow reasoning about the overall security policy. Throughout, we illustrate the developments by examples drawn from health service policies.