Secure proxy signature scheme with fast revocation in the standard model

Proxy signature is an important cryptographic primitive and has been suggested in numerous applications. The revocation of delegated rights is an essential issue of the proxy signature schemes. In this article,a security model of proxy signature schemes with fast revocation is formalized. Under the formal security framework,a proxy signature scheme with fast revocation based on bilinear pairings is proposed. A security mediator (SEM),which is an on-line partially trusted server,is introduced to examine whether a proxy signer signs according to the warrant or he/she exists in the revocation list. Moreover,the proxy signer must cooperate with the SEM to generate a valid proxy signature,thus the proposed scheme has the property of fast revocation. The proposed scheme is provably secure based on the computational Diffie-Hellman (CDH) intractability assumption without relying on the random oracles,and satisfies all the security requirements for a secure proxy signature.