XPath translation to enhance the semantic matching of fine-grained Web service security policies

Fine-grained Web service security policies contain protection assertions that include XPath expressions pointing to the message data to be secured. However, existing security policy (SP) matching approaches don't take into account the structural heterogeneities that may exist between the requestor and provider data. In this paper, we show how this can lead to wrong SP matching results and propose an XPath translation approach that makes the XPath expressions in a requestor and provider SPs refer to the same XML schema so that they may be correctly compared. We also implement our XPath translator, integrate it into our previous SP matcher, and validate the correctness of matching fine-grained protection assertions through several tests and a real-world use case.