brucker.ea:efficient:2010 BookSection Heidelberg Springer-Verlag 2010 International Symposium on Engineering Secure Software and Systems (ESSoS) 5965 157-165 BruckerAchimD PetritschHelmut MassacciF WallachD ZannoneN Idea: Efficient Evaluation of Access Control Constraints Business requirements for modern enterprise systems usually comprise a variety of dynamic constraints, i.e., constraints that require a complex set of context information only available at runtime. Thus, the efficient evaluation of dynamic constraints, e.g., expressing separation of duties requirements, becomes an important factor for the overall performance of the access control enforcement. Especially in highly distributed systems, e.g., systems based on the service-oriented architecture (SOA) paradigm, the time for evaluating access control constraints depends significantly on the protocol between the central policy decision point (PDP) and the distributed policy enforcement points (PEP). In this paper, we present an policy-driven approach for generating customized protocol for the communication between the PDP and the pep. Moreover, we provide a detailed comparison of several approaches for querying context information during the evaluation of access control constraints.