Improvement of ID-based proxy signature scheme without trusted PKG
基于身份的无可信私钥产生中心的代理签名方案的改进

A security defect was detected in ZUO Wei-ping's ID-based designated verifier proxy signature scheme without trusted PKG. The proxy signer can compute the original signer's private key after receiving his authorization. An improved scheme was presented to overcome the above defect. Analysis indicates that it is secure against the proxy signer's forgery attack, and even against the malice attack of the ally of the proxy signer and the PKG.