On context in authorization policy

Authorization policy infrastructures are evolving with the complex environments that they support. However, the requirements and technologies supporting context are not yet well understood. Often implemented as condition functions or predefined attributes, context is used to more precisely control when and how policy is enforced. This paper considers context requirements and services in authorization policy. The properties and security requirements of context evaluation are classified. A key observation gleaned from this classification is the degree to which context functions share common properties. The Antigone Condition Framework (ACF) exploits these commonalities to provide a general purpose condition service and associated API. The prototype ACF design is presented and illustrated, and directions for future work considered.