Proxy undeniable signatures
强代理不可否认签名

Proxy signatures allow an original signer to entrust a proxy signer to sign messages on behalf of him. Undeniable signatures ensure that only the signer can confirm or deny the validity of a given signature to the third party. For the need of some practical applications, the proxy signature and the undeniable signature were combined together, and a new concept of proxy undeniable signature was proposed. The proxy undeniable signature scheme's security could be proved under the decisional Diffie-Hellman assumption.