Design of a Role-Based Trust-Management Framework

We introduce the RT framework, a family of Rolebased Trust-management languages for representing policies and credentials in distributed authorization. RT combines the strengths of role-based access control and trustmanagement systems and is especially suitable for attributebased access control. Using a few simple credential forms, RT provides localized authority over roles, delegation in role definition, linked roles, and parameterized roles. RT also introduces manifold roles, which can be used to express threshold and separation-of-duty policies, and delegation of role activations. We formally define the semantics of credentials in the RT framework by presenting a translation from credentials to Datalog rules. This translation also shows that this semantics is algorithmically tractable.