XML Security Views Revisited

In this paper, we revisit the view based security framework for XML without imposing any of the previously considered restrictions on the class of queries, the class of DTDs, and the type of annotations used to define the view. First, we show that the full class of Regular XPath queries is closed under query rewriting. Next, we address the problem of constructing a DTD that describes the view schema, which in general needs not be regular. We propose three different methods of approximating the view schema and we show that the produced DTDs are indistinguishable from the exact schema (with queries from a class specific for each method). Finally, we investigate problems of static analysis of security access specifications.