Specifiable Proxy Signature Schemes

Abstract

Since Mambo et al. proposed the concept of proxy signatures in 1996, many proxy signature schemes were proposed. Two of the proposed schemes integrated the specification of the proxy period into the proxy signature scheme. Besides the proxy period, there is some other important specification of the proxy. Therefore, we propose a basic scheme providing the verifiable mechanism for the proxy specification. On the other hand, in these proposed schemes, the original signer is so powerful that he can forge proxy signatures. If the proxy signatures should be identified, this may causes critical damages on the benefit of the proxy signer. To overcome this unreasonable disadvantage, we propose an advanced proxy signature scheme. Then the advanced scheme provides the fair security protection for the proxy signers and the original signer.