Felkner, A
Role-based Trust management (RT) languages are used for representing policies and credentials in decentralized, distributed access control systems. They combine trust management and Role-Based Access Control features. The subject of this paper is an operational semantics for the family of RT languages, in which credentials can be established using a simple set of inference rules. A credential provides information about the keys, rights and qualifications from one or more trusted authorities. The inference system applied not only to the basic language of the Role-Based Trust management family (RT 0),but also to the other members of the family up to RT T, which is much more sophisticated. RT T provides manifold roles and role-product operators to express threshold and separation-of-duty policies. A manifold role defines sets of entities whose cooperation satisfies the manifold role. It enables to express such a condition, which need more than one member of a role to effectively fulfil the particular task.