Abstract
Over the last several years, sophisticated access control models have been proposed to take into account different dimensions such as time, space, role, context, attribute, etc. These enable specification of fine grained access control policies that can better express evolving organizational needs. However, there is no comprehensive solution that can uniformly specify, evaluate, maintain and analyze this multitude of policies in a consistent fashion. In this paper, we show that specifying and enforcing access control policies of multiple granularities and dimensions can be transformed into the problem of storing and querying data at multiple granularities and dimensions. Specifically, we develop a unified schema to represent several standard access control policies and show how they can be automatically evaluated. We have implemented the system in Oracle, and evaluated its scalability.