A Secure Non-Repudiable General Proxy Signature

A threshold proxy signature scheme allows any or more proxy signers to cooperatively sign messages on behalf of an original signer, but or fewer proxy signers cannot. In this paper, in order to adapt to some practical applications, by a modification of Hu threshold proxy signature, we propose a novel secure variation of proxy signature scheme called general proxy signature scheme. This scheme has some advantages over the threshold scheme, in the sense that the subsets of proxy group that allow to sign messages on behalf of an original signer, are not necessarily defined according to their cardinality and it becomes this proposed concept more attractive and practical when the members of a proxy group do not all have the same power or influence. Also, it is more efficient. This scheme is proved to enjoy security against the existing attacks.