支持授权撤销的代理签名分析与改进

在基于时间戳撤销机制的代理签名方案中，授权服务器(AS)签发的时间戳内并不包含原始签名人的授权信息，使攻击者可以利用该缺陷绕过AS检查，获得合法的时间戳签名。为此，对AS生成时间戳阶段进行改进，使攻击者无法获得能够通过验证的时间戳签名，从而弥补原方案的安全缺陷。

Analysis and Improvement of Proxy Signature Supporting Authorization Revocation

According to in-depth security analyzing of a proxy signature scheme with revocation by the use of timestamp,it points out that the malicious proxy signer can obtain a valid timestamp whatever the original signer revoked the delegation or not because the time-stamp issued by Authentication Sserver（AS） do not bind with the delegation of original signer.Pointing at the problems existed in the timestamp generation phase,this paper proposes a more efficient scheme with fast revocation,which solves the weaknesses of original scheme fundamentally.