Abstract: The article designs a fair contract signing protocol by embedding users’identy information into Schnorr signature.Compared with existing had not embedding the users’ identy information into the contract signing protocol，this protocol has a better fairness.Moreover the protocol also introduces n off-line semi-trusted third parties，the analysis has indicated that it realizes not only the signers’ privacy protection，but also the reduced probability that one party conspires with off-line semi-trusted third parties to gain another party’s signature.It is based on Publicly Verifiable Secret Sharing（PVSS） theory.

Key words: Schnorr-signature, Publicly Verifiable Secret Sharing（PVSS）, identy information, semi-trusted third party

摘要： 通过在Schnorr签名中嵌入用户的身份信息设计了一个公平的合同签署协议。与已有的没有嵌入用户身份信息的合同签署协议相比，该协议具有更好的公平性。另外本协议还引入了n个离线的半可信第三方，分析表明这不仅实现了签名者隐私的保护，还有效地降低了签名者中的一方与离线半可信第三方合谋来获取另一方签名的概率，它的理论基础是公开可验证秘密分享。

关键词: Schnorr签名, 公开可验证秘密分享, 身份信息, 半可信第三方