Efficient Strong Fair Concurrent Signature Scheme

We propose a fair novel concurrent signature scheme. It resolves the existing problems in traditional concurrent signature schemes, that is initial signer (A) has some advantages over matching signer (B), such as A could show B´s ambiguous signature and the keystone to a third party in private to demonstrate B´s binding signature but B can not, or A could keep the keystone secret and B do not have power to force A to release it. In our scheme, the keystones were produced by both A and B, that is to say, the two participants in our scheme have equal positions, no one has any priority than the other, so our scheme can achieve the fairness of both sides.