Fine-grained integration of access control policies

Collaborative and distributed applications, such as dynamic coalitions and virtualized grid computing, often require integrating access control policies of collaborating parties. Such an integration must be able to support complex authorization specifications and the fine-grained integration requirements that the various parties may have. In this paper, we introduce an algebra for fine-grained integration of sophisticated policies. The algebra, which consists of three binary and two unary operations, is able to support the specification of a large variety of integration constraints. For ease of use, we also introduce a set of derived operators and provide guidelines for users to edit a policy with desired properties. To assess the expressive power of our algebra, we define notion of completeness and prove that our algebra is complete and minimal with respect to the notion. We then propose a framework that uses the algebra for the fine-grained integration of policies expressed in XACML. We also present a methodology for generating the actual integrated XACML policy, based on the notion of Multi-Terminal Binary Decision Diagrams. Experimental results have demonstrated both effectiveness and efficiency of our approach. In addition, we also discuss issues regarding obligations.