Verifiable Outsourced Computation with Full Delegation

With the development of cloud computing, verifiable computation (VC) has attracted considerable attentions due to its importance. However, the existing VC schemes suffer from two substantial shortcomings that limit their usefulness: (i) they have to invest expensive computational tasks in the preprocessing stage, which has exceeded the available computation capacity of the client, and (ii) they do not support frequent updates, so that each update needs to perform the computation from scratch. To resolve these problems, we propose a novel primitive called verifiable outsourced computation with full delegation (FD-VC), which greatly reduces the computation cost of the client by delegating the preprocessing to the cloud. During this phase, the cloud cannot obtain any knowledge of the verification key. To the best of our knowledge, it is the first VC scheme not only supporting full delegation but also supporting dynamic update. The highlight of our scheme is that verification and update cost are constant and independent of the degree of the polynomial. Our scheme is provably correct and secure based on bilinear pairing and the hardness assumption of Bilinear Diffie-Hellman Exponent problem, and our analyses show that our scheme is very practical and suitable for the real world applications.