两个代理签名方案的密码学分析

最近，戴等人提出了一种指定接收人的代理签名方案和一种消息保密的代理签名方案。在本文中，给出了这两个代理签名方案的安全分析，指出它们是不安全的，都不能抵抗原始签名者的伪造攻击。

Cryptanalysis of Two Proxy Signatures Schemes

Recently, Dai et al.propose a designated-receiver proxy signature scheme and a proxy signature scheme with privacy protection. In this paper, we give security analysis of the two proxy signature schemes. The schemes are all insecure against the original signer's forgery attack.