New concurrent digital signature scheme based on the computational Diffie-Hellman problem

Based on strong designated verifiers signatures, a new fair concurrent signature scheme is proposed. Compared with the previous concurrent signature schemes, even if a keystone must be chosen by the initial signer, the matching signer will easily get the keystone through an extraction algorithm. Due to the property of strong designate verifying, the initial signer couldn't make use of the keystone prepared carefully to deceive the matching signer. Then the matching signer is able to participate actively the signature scheme. Besides, there aren't bilinear operations in the keystone algorithm to deliver the keystone efficiently. Therefore the efficiency of our signature scheme is also improved.