A General and Flexible Access-Control System for the Web

The authors describe the design, implementation, and performance of a new system for access control on the web. To achieve greater flexibility in forming access-control policies-in particular, to allow better interoperability across administrative boundaries-the authors base the system on the ideas of Proof-Carrying Authorization (PCA). The authors extend PCA with the notion of goals and sessions, and add a module system to the proof language. The access-control system makes it possible to locate and use pieces of the security policy that have been distributed across arbitrary hosts.