Abstract: An improved threshold signature scheme is proposed to overcome the weakness of Cai et al’s scheme. The security of this scheme is analyzed. The results show that the improved scheme can not only resist conspiracy attacks and forgery attacks essentially, but also protect the personal broadcasted information with applying message recovery equation. In addition, it can realize the computing ability of group’s public key by constructing a secure distributed key generation protocol. As a result, the improved scheme is securer than the former schemes.

Key words: threshold signature, conspiracy attack, forgery ability, inside attack

摘要： 在分析蔡永泉等的抗合谋攻击的[(t,n)]门限签名方案安全缺陷的基础上，针对提出的攻击给出了一种改进方案；对改进方案的安全性进行了分析。结果表明：改进方案不仅能从根本上抵抗合谋攻击和伪造签名攻击，而且通过对消息恢复方程的应用保护了签名者的秘密信息和广播数据，同时通过构造安全的分布式密钥生成协议保证了群公钥的可计算性，因此比原方案具有更高的安全性。

关键词: 门限签名, 合谋攻击, 伪造性, 内部攻击