无可信中心的可变门限签名方案

Changeable Threshold Signature Scheme without a Trusted Center

分析了Lee的多策略门限签名方案,发现其不能抗合谋攻击.基于Agnew等人改进的ElGamal签名方案,提出了一个无可信中心的可变门限签名方案.该方案允许在群体中共享具有不同门限值的多个组密钥,每个签名者仅需保护一个签名密钥和一个秘密值;可以根据文件的重要性灵活地选取不同的门限值进行门限签名.分析表明,提出的方案防止了现有方案中存在的合谋攻击,而且无需可信中心来管理签名者的密钥,密钥管理简单,更具安全性和实用性.

Analyses are made on Lee＇s threshold signature scheme with multiple signing policies, which shows his scheme suffers from allied cheating attack. Then, based on Agnew et al. ＇s improved E;Gamal signature algorithm, a changeable threshold signature scheme without a trusted center is proposed. Multiple group secret keys with different threshold values are shared among a group of signers, and each signer needs to keep only one secret key and one secret value. Different group secret keys can be flexibly chosen to securely sign documents depending on their significance. Analysis results show that the proposed scheme can protect the signature from allied cheating attack and the key management is very simple since there is no trusted center. Therefore, the proposed scheme is more secure and capable of providing more practicability than the existing schemes.