Zás - aspect-oriented authorization services

This paper proposes Zás, a novel, flexible, and expressive authorization mechanism for Java. Zás has been inspired by Ramnivas Laddad’s proposal to modularize Java Authentication and Authorization Services (JAAS) using an Aspect-Oriented Programming (AOP) approach. Zás’ aims are to be simultaneously very expressive, reusable, and easy to use and configure. Zás allows authorization services to be non-invasively added to existing code. It also cohabits with a wide range of authentication mechanisms. Zás uses Java 5 annotations to specify permission requirements to access controlled resources. These requirements may be changed directly during execution. They may also be calculated by client supplied permission classes before each access to the corresponding resource. These features, together with several mechanisms for permission propagation, expression of trust relationships, depth of access control, etc., make Zás, we believe, an interesting starting point for further research on the use of AOP for authorization.