Zás – An Aspect-Oriented Access Control Framework

Traditionally, access control system architectures are based on the abstract reference monitor model proposed by Anderson, which tries to separate the access control logic from the logic of applications. The implementation of this model has been difficult since access control presents itself as a crosscutting concern, i.e., it crosscuts the functionalities of applications. However, the developments of the techniques that support the separation of concerns, particularly aspect oriented programming, have been enabling the development of systems in which the access control code is not scattered through the code of the application. Nevertheless, these solutions are still too specific to a given application. This work presents an access control framework for Java applications, named Zás, which can be reused and that applies the abstract reference monitor proposed by Anderson. This framework supports access control policies using different kinds of context information and allows them to be changed at runtime. Zás was developed in the aspect oriented programming language AspectJ and it uses Java 5 annotations. We used Zás in several small applications since its inception, so as to gain experience and insight from its application. Nevertheless, to evaluate the performance and applicability of the final version of the Zás framework prototype, we integrated it in a very large Web application called Fénix, which brought us very interesting results, such as showing the easiness of applicating Zás to already existing applications, and also the main caveats and limitations of Zás.