On the sequence of authorization policy transformations

In [2, 3], we proposed a model-based approach to specify the transformation of authorizations based on the principle of minimal change [10] and its application in database systems. Nevertheless, there were some limitations in this approach. Firstly, we could not represent a sequence of transformations. Secondly, default authorizations could not be expressed. In this paper, we propose two high-level formal languages, Ls and Lsd, to specify a sequence of authorization transformations and default authorizations. Our work starts with Ls, a simple, but expressive, language to specify certain sequence of authorization transformations. Furthermore, Lsd has more powerful expressiveness than Ls in the sense that constraints, causal and inherited authorizations, and general default authorizations can be specified.