Privacy-preserving Semantic Interoperation of Heterogeneous Databases

Two major challenges to enabling secure interoperation among web-information sources are resolving semantic heterogeneity across websites and maintaining the privacy of the data and metadata of organizations owning the websites. In this paper, we propose SACE, a novel, implemented middleware toolkit that enables privacy-preserving secure semantic access control and allows queries to be answered across websites despite their heterogeneity. SACE implements role-based access control after accounting for differences in roles across organizations. The novelty of SACE lies in its architecture that routes data and queries through different encrypted channels and reduces hacking vulnerabilities to a minimum. Although a middleware-based solution, in order to preserve the privacy of the metadata, SACE discloses minimum information to even the mediator encrypted ontologies, encrypted ontology-mapping tables and conversion functions, encrypted role hierarchies and encrypted queries. The toolkit also requires minimal changes to existing websites or their underlying databases. We show that despite using encrypted query and encrypted data translations, the toolkit provides acceptable performance.