Designated Verifier Proxy Signature Scheme Without Random Oracles

摘要

In a designated verifier proxy signature scheme, one can delegate his or her signing capability to another user in such a way that the latter can sign messages on behalf of the former, but the validity of the resulting signatures can only be verified by the designated verifier. Several designated verifier proxy signature schemes have been proposed so far. However, most of the schemes were proven secure in the random oracle model, which has received a lot of criticism since the security proofs in the random oracle model are not sound with respect to the standard model. In this paper, we propose a new construction of designated verifier proxy signature whose security can be proven without using the random oracle model. Our scheme is inspired by Waters' Identity-based encryption. The unforgeability of our scheme is based on the hardness of Gap Bilinear Diffie-Hellman problem. As far as we know, this is the first designated verifier proxy signature secure in the standard model.