Efficient Verifiable Databases With Insertion/Deletion Operations From Delegating Polynomial Functions

The notion of verifiable database with updates (VDB) enables a resource-limited client to securely outsource a very large database to an untrusted server, and the client could later retrieve a database record and update it efficiently. In addition, the client could detect any misbehavior of tampering with the data record by the server. To the best of our knowledge, the existing VDB schemes cannot efficiently support all updating operations (i.e., insertion, deletion, and replacement) simultaneously. In this paper, we introduce a new primitive called Merkle sum hash tree and then use it to design a new VDB scheme that supports for all updating operations from delegating polynomial functions. An interesting property of our scheme is that all updating operations can be viewed as a special case of “replacement” in the Benabbas–Gennaro–Vahlis VDB scheme. Thus, our construction is very efficient for real-world applications. Furthermore, we formally prove that the proposed construction can achieve the desired security properties when the subgroup member assumption holds.