中文摘要：

为克服现有的无可信中心门限签名方案的安全缺陷，提出了一种抗合谋攻击门限签名方案．该方案不仅能从本质上抵抗合谋攻击，而且能保证签名者身份的匿名性和可追查性．另外，还提出一种合谋攻击方式，并应用此方法对现有方案与所提方案进行了攻击对比测试．结果表明，现有方案在此攻击下签名的安全性无法保证，而该方案可以有效地抵抗此类攻击．

英文摘要：

In order to overcome the security defect of the existing threshold signature scheme, a threshold signature scheme withstanding the conspiracy attack is proposed. Analysis shows that this scheme can not only resist conspiracy attacks essentially, but also provide anonymity and traceability simultaneously. In addition, a conspiracy attack is designed in this paper, which is adopted to test the current schemes and the scheme presented. The result shows that current schemes can not ensure the signature security, however, the proposed scheme can cope with this attack effectively.