一种安全的门限群签名方案*

门限签名是一类重要的数字签名，到目前为止，已有许多门限方案相继被提出，但它们都是不安全的，几乎都有弱点：当恶意成员大于或等于门限时，能以高概率获取系统秘密，并由此伪造群签名。在现有门限方案的基础上提出了一种比较安全的门限群签名方案，新方案较已有的方案性能更好，尤其是克服了已有方案的缺点。最后对新方案的安全性进行了讨论。

Secure Threshold Group Signature Scheme

Threshold signature is an important digital signature.Up to now,many threshold signature schemes are proposed.But none of them is secure.There are some weaknesses in these schemes: when the number of malicious shareholders is more than the threshold,they can obtain the secret of the group with high probability,then they can forge group signature.A secure threshold group signature scheme is set up in this paper based on the analysis of previous schemes.This scheme has more efficient performance when compared with the previous schemes.Especially, an attractive property of this scheme is that it overcomes the weakness of previous schemes.Finally,the security of the new scheme is analyzed and discussed.