Generalized XML Security Views

We investigate a generalization of the notion of XML security view introduced by Stoica and Farkas [45] and later refined by Fan et al. [23]. The model consists of access control policies specified over DTDs with XPath expressions for data-dependent access control. We provide the notion of security views characterizing information accessible to authorized users. This is a transformed DTD schema that can be used by users for query formulation. We develop an algorithm to materialize an authorized version of the document from the view and an algorithm to construct the view from an access control specification. We show that our view construction combined with materialization produces the same result as the direct application of the DTD access specification on the document. We also propose a number of generalizations of possible security policies and show how they affect view construction algorithm. Finally, we provide an evaluation of our system.