A new anonymous but accountable secure proxy signature scheme

Privacy has become one of the most important human rights of the modern age. In order to verify the validity of the proxy signature, the verifier need get the original signers' public key and the proxy signer's public key. Obviously, the verification would leak the relationship between the proxy signer and the original signer. Using the technology of pseudonym, in this paper, we propose a simple secure anonymous but accountable method for proxy signer in a proxy signature scheme. Unless the corresponding evidence has been provided by the original signer, no one can find the proxy signer's real identity or public key. In the scheme, the can reveal the identity of the proxy signer; moreover, the original signer can also demonstrate the identity of the proxy signer. Specially, we realize the property of anonymous but accountable without complex computation and trusted third party which is different to earlier method. The method can be used in any proxy signature scheme based on warrant to reach the target of proxy signer's anonymity and accountability.