Privacy-Preserving Verification of Aggregate Queries on Outsourced Databases

It is often desirable to be able to guarantee the integrity of historical data, ensuring that any subsequent modifications to the data can be detected. It would be especially convenient to extend such proofs of integrity to certain computations performed later using the historic data. We approach this question in the context of outsourced databases, where a data owner delegates the ability to answer users’ queries to a service provider, and distrustful users may desire to verify the integrity of responses to their queries on the data. We present a solution for integrity verification of database aggregate queries, such as SUM and MAX. We design proofs of correctness and completeness of aggregate results. What makes the problem challenging is that individual data entries may be sensitive (e.g. as in medical databases), and should not be revealed to the user. We give cryptographic protocols to support verification of query results in a privacy-preserving fashion.