Probabilistic Access Policies with Automated Reasoning Support

Abstract Existing access policy languages like Cedar equipped with SMT-based automated reasoning capabilities are effective in providing formal guarantees about the policies. However, this scheme only supports access control based on deterministic information. Observing that certain information useful for access control can be described by random variables, we are motivated to develop a new paradigm of access control in which access policies contain rules about uncertainty, or more precisely, probabilities of random events. To compute these probabilities, we rely on probabilistic programming languages. Additionally, we show that the probabilistic part of these policies can be encoded in linear real arithmetic, which enables practical automated reasoning tasks such as proving relative permissiveness between policies. We demonstrate the advantages of the proposed probabilistic policies over the existing paradigm through two case studies on real-world datasets with a prototype implementation.