Proxy Protected Signature Attack

Through the in-depth study of literatures in this paper, there are three attack types in proxy signature schemes. First, it is the original signer's attack. For this attack, an authorized person who also holds authorized-private-key may pretend to a legal proxy signer generating a valid proxy signature, and then cheat the verifier. According to the way of attack, the attack scheme is proposed. Then we propose a proxy-protected signature scheme based on Elliptic Curve Discrete Logarithm Problem (ECDLP). Second, it is the un-delegated proxy signer's attack in which any other attacker without the original signer's delegation can generate a valid proxy-protected signature. We propose an improved scheme of Zhou et al.'s RSA scheme above attack. Third, it is the forged-warrant attack, namely, after a set of valid proxy-protected signature is formed by a proxy signer, the attacker forges a valid proxy-protected signature with his reconstructed warrant by using the legal proxy signature. Aiming at this attack, specific attack algorithms are proposed and the improved schemes for the attack based on RSA and integer factor decomposition are proposed respectively to protect proxy signer. Finally, the security analysis of new schemes is given. Through the analysis, the new schemes can effectively prevent the above attacks, and there has been a great rise in security. They do not enable anyone (including the original signer) generate efficient proxy-protected signature and best protect the signature right of the proxy signer.