In this paper we make a contribution to the proof and trust layer of the Semantic Web layer cake by integrating two well founded techniques, namely DAML-S (for describing Web services with machine-processable semantics) and SPKI/SDSI (for specifying authorization based access control). Our approach builds on the idea of autonomous granting of access rights and decision making based on independent trust structures. Our framework allows the specification of access control related and functionality related aspects in a unified way that is manageable and efficient. Therefore, our approach is useful not only in typical Web service based applications (client-server architecture) but also in peer to peer and agent based applications.