Lattice-Based Multi-party Concurrent Signatures Scheme

Concurrent Signatures scheme is an effective way to solve the problem of fair exchange without the help of any trusted third party, it has the advantage of efficiency. Until now, all concurrent signatures are based on traditional cryptosystems, but the emergence of quantum computing poses a severe threat to the security of classic public-key cryptosystems. More and more attentions are being paid to lattice-based cryptosystems, which is one of the candidate cryptosystems against the attacks from quantum computing. In this paper we present a new formal model of multi-party concurrent signatures scheme which is constructed based on constant-size ring signatures, and a lattice-based multi-party concurrent signatures scheme. The scheme has comparative advantages in both efficiency and security over the existing concurrent signatures schemes based on traditional cryptosystems. In particular, our scheme is constructed based on constant-size ring signatures, and thus we have solved the open problem: how to construct a multi-party concurrent signatures scheme based on constant-size ring signatures, which was proposed by Dongvu Tonien, Willy Susilo and Reihaneh Safavi-Naini in 2006.