Abstract--The paper proposes an approach to content dissemination that exploits the structural properties of an Extensible Markup Language (XML) document object model in order to provide an efficient dissemination and at the same time assuring content integrity and confidentiality. Our approach is based on the notion of encrypted postorder numbers that support the integrity and confidentiality requirements of XML content as well as facilitate efficient identification, extraction, and distribution of selected content portions. By using such notion, we develop a structurebased routing scheme that prevents information leaks in the XML data dissemination, and assures that content is delivered to users according to the access control policies, that is, policies specifying which users can receive which portions of the contents. Our proposed dissemination approach further enhances such structurebased, policy-based routing by combining it with multicast in order to achieve high efficiency in t...