Securely updating XML

We study the problem of updating XML repository through security views. Users are provided with the view of the repository schema they are entitled to see. They write update requests over their view using the XUpdate language. Each request is processed in two rewriting steps. First, the XPath expression selecting the nodes to update from the view is rewritten to another expression that only selects nodes the user is permitted to see. Second the XUpdate query is refined according to the write privileges held by the user