XML Access Control Using Static Analysis Makoto Murata Akihiko Tozawa Michiharu Kudo IBM Tokyo Research Lab/IUJ IBM Tokyo Research Lab IBM Tokyo Research Lab Research Institute 1623-14, Shimotsuruma, 1623-14, Shimotsuruma, 1623-14, Shimotsuruma, Yamato-shi, Yamato-shi, Yamato-shi, Kanagawa-ken 242-8502, Kanagawa-ken 242-8502, Kanagawa-ken 242-8502, Japan Japan Japan
[email protected] [email protected] [email protected] ABSTRACT 1. INTRODUCTION Access control policies for XML typically use regular path XML [5] has become an active area in database research. expressions such as XPath for specifying the objects for ac- XPath [6] and XQuery [4] from the W3C have come to be cess control policies. However such access control policies widely recognized as query languages for XML, and their are burdens to the engines for XML query languages. To implementations are actively in progress. In this paper, relieve this burden, we introduce static analysis for XML we are concerned with fine-grained (element- and attribute- access control. Given an access control policy, query expres- level) access control for XML database systems rather than sion, and an optional schema, static analysis determines if document-level or collection-level access control. We be- this query expression is guaranteed not to access elements lieve that access control plays an important role in XML or attributes that are permitted by the schema but hidden database systems, as it does in relational database systems. by the access control policy. Static analysis can be per- Some early experiences [21, 10, 3] with access control for formed without evaluating any query expression against an XML documents have been reported already.