摘要： 已有的代理重签名方案大多是存在性不可伪造的,攻击者能对已经签名过的消息重新伪造一个有效的签 名,但强不可伪造性能阻止攻击者对已经签名过的消息签名对进行重新伪造。为此,利用目标抗碰撞(TCR)杂凑 函数,提出一种双向代理重签名方案。基于TCR 杂凑函数的抗碰撞性和计算性Diffie-Hellman 假设,证明方案在适 应性选择消息攻击下是强不可伪造的。分析结果表明,该方案在计算效率上优于现有的强不可伪造代理重签名方 案,系统公开参数长度、签名长度和重签名长度更短,且满足更多的安全属性。

关键词: 双向代理重签名, 强不可伪造性, 可证明安全, 计算性Diffie-Hellman 假设, 标准模型

Abstract: Most existing proxy re-signature schemes are existential unforgeability,where an adversary will be able to forge a signature on a new message rather than on a message that has already been signed. However,strong unforgeability can protect the existing message-signature pairs from being forged. By using TCR hash function,a bidirectional proxy resignature scheme is proposed. Based on collision-resistant Target Collision Resistant ( TCR ) hash function and computational Diffie-Hellman assumption,the proposed scheme is proved to be strongly unforgeable under adaptive chosen message attacks. The results show that the proposed scheme in computational efficiency is superior to the available proxy re-signature schemes with strong unforgeability. Compared with these schemes,the new scheme has short system parameters,short signature,short re-signature and more security properties.

Key words: bidirectional proxy re-signature, strong unforgeability, provable security, Computational Diffie-Hellman (CDH) assumption, standard model

中图分类号: 

• TP309. 7