Authentication of Outsourced Databases Using Signature Aggregation and Chaining

Abstract

Database outsourcing is an important emerging trend which involves data owners delegating their data management needs to an external service provider. Since a service provider is almost never fully trusted, security and privacy of outsourced data are important concerns. A core security requirement is the integrity and authenticity of outsourced databases. Whenever someone queries a hosted database, the results must be demonstrably authentic (with respect to the actual data owner) to ensure that the data has not been tampered with. Furthermore, the results must carry a proof of completeness which will allow the querier to verify that the server has not omitted any valid tuples that match the query predicate. Notable prior work ([4,9,15]) focused on various types of Authenticated Data Structures. Another prior approach involved the use of specialized digital signature schemes. In this paper, we extend the state-of-the-art to provide both authenticity and completeness guarantees of query replies. Our work analyzes the new approach for various base query types and compares it with Authenticated Data Structures. We also point out some possible security flaws in the approach suggested in the recent work of [15].