Revocation in the privilege calculus ?

We have previously presented a framework for updating privileges and creating management structures by means of authority certificates. These are used both to create access-level permissions and to delegate authority to other agents. In this paper we extend the framework to support a richer set of revocation schemes. As in the original, we present an associated calculus of privileges, encoded as a logic program, for reasoning about certificates, revocations, and the privileges they create and destroy. The discussion of revocation schemes follows an existing classification in the literature based on three separate dimensions: resilience, propagation, and dominance. The first does not apply to this framework. The second is specified straightforwardly. The third can be encoded but raises a number of further questions for future investigation.