D-algebra for composing access control policy decisions

This paper proposes a D-algebra to compose decisions from multiple access control policies. Compared to other algebra-based approaches aimed at policy composition, D-algebra is the only one that satisfies both functional completeness (any possible decision matrix can be expressed by a D-algebra formula) and computational effectiveness (a formula can be computed efficiently given any decision matrix). The D-algebra has several relevant applications in the context of access control policies, namely the analysis of policy languages decision mechanisms, and the development of tools for policy authoring and enforcement.