A nonrepudiable multi-proxy multi-signature scheme

In this paper, the authors first review Hwang el al's a new multi-proxy multi-signature scheme and point out its disadvantages. To overcome the weakness, a nonrepudiable multi-proxy multi-signature scheme based on Hwang et al's scheme, is proposed. The improved version can provide the fair protection for the original signer group and the proxy group. Moreover, it is secure against the forgery attack without the secure channel.