Abstract: The security of the proxy blind signature scheme which is proposed by Tan et al is analyzed，and it is found that this scheme can’t satisfy the unforgeability and the unlinkability requirement.This paper presents an improved scheme that can overcome the security problems existing in Tan et al’s scheme.The new scheme improves the signing equations in signing phase.Consequently，its security is equivalent to find a solution to the discrete logarithm problems against the universal forgery attack.Moreover，the receiver’s private key is introduced in extraction phase，which ensures the proxy signer can’t make a linkage between the signature on message and the signature on corresponding blind message.

摘要：

通过对Tan等人提出的代理盲签名方案进行分析，指出该方案不满足不可伪造性，且签名是可追踪的。为了克服上述不足之处，提出了一种改进的方案。新方案对签名阶段进行改进，当面对一般性的伪造攻击时，其安全性等价于解离散对数难题。同时，在签名提取阶段引入签名接收者的私钥，代理签名人无法将盲消息的签名和消息签名联系起来，即签名是不可追踪的。