Proxy signature scheme with fast revocation

Many proxy signature schemes have the defect that they cannot solve the proxy revocation problem.Based on the bilinear pairings,a new proxy signature scheme is proposed in this paper.Motivated by the idea of(2,2) threshold,a security mediator(SEM) is introduced in our scheme to(1) help a proxy signer to generate valid proxy signatures,(2) examine whether a proxy signer signs according to the warrant,and(3) check the revocation of a proxy signer.It is shown that the proposed scheme satisfies all the security requirements for a secure proxy signature.Moreover,a proxy signer must cooperate with the SEM to generate a valid proxy signature,which makes the new scheme have an effective and fast proxy revocation.