Distributed Access-Rights Management with Delegation Certificates

New key-oriented discretionary access control systems are based on delegation of access rights with public-key certificates. This paper explains the basic idea of delegation certificates in abstract terms and discusses their advantages and limitations. We emphasize decentralization of authority and operations. The discussion is based mostly on the SPKI certificates but we avoid touching implementation details. We also describe how threshold and conditional certificates can add flexibility to the system. Examples are given of access control between intelligent networks services.