A Mediated Proxy Signature Scheme with Fast Revocation for Electronic Transactions

Proxy signature schemes allow an original signer to delegate his signing rights to a proxy signer. Most proxy signature schemes have succeeded for proxy delegations and they are considered very useful methods when one needs to delegate his signing power to other person in digital business. However, many proxy signature schemes have the defects that cannot solve proxy revocation problems. Moreover, they cannot provide the immediate revocation, even if a proxy signer colludes with any malicious attacker. In this paper, we propose a mediated proxy signature scheme with fast revocation. Our scheme solves the weaknesses of most proxy signature schemes and satisfies the security requirements for proxy signature scheme. And it also provides an effective proxy revocation whenever the original signer wants or signer's key is compromised.