Efficient Execution of Aggregation Queries over Encrypted Relational Databases

Abstract

Encryption is a common method to assure privacy of stored data. In many practical situations, decrypting data before applying logic compromises privacy. The challenge is to come up with logic transformation techniques and result-mapping methods so that the exact result of applying logic to data-in-the-clear is obtained by applying the transformed logic to encrypted data and mapping the result produced. In the scope of relational aggregation queries and in the presence of logical predicates, we show how to support needed transformations and mappings.