Compliance checking for usage-constrained credentials in trust negotiation systems

We propose an approach to placing usage-constraints on RT credentials; issuers specify constraints by designing non-deterministic finite automata. We show by examples that this approach can express constraints of practical interest. We present a compliance checker in the presence of usage-constraints, especially for trust negotiation systems. Given an RT policy, the checker is able to find all minimal satisfying sets, each of which uses credentials in a way consistent with given constraints. The checker leverages answer set programming, a declarative logic programming paradigm, to model and solve the problem. We also show preliminary experimental results: supporting usage-constraints on credentials incurs affordable overheads and the checker responds efficiently.