Abstract

Database outsourcing model is emerging as an important new trend beside the “application-as-aservice” model. In this model, since a service provider is typically not fully trusted, security and privacy of outsourced data are significant issues. These problems are referred to as data confidentiality, user privacy, data privacy, and query assurance. Among them, query assurance takes a crucial role to the success of the database outsourcing model. To the best of our knowledge, however, query assurance, especially for outsourced XML databases, has not been concerned reasonably in any previous work. In this paper, we propose a novel index structure, named Nested Merkle B+-Tree, combining the advantages of B+-tree and Merkle Hash Tree to completely deal with three issues of query assurance known as correctness, completeness and freshness in dynamic outsourced XML databases. Experimental results with real-world datasets prove the efficiency of our proposed solution.