基于分组秘密共享的(t,n)门限群签名体制

已有的门限群签名体制无法抵抗合谋攻击的原因，是群中任意t或更多个成员共享的秘密就是群密钥，所以群中任何一组成员合谋可以恢复群密钥，从而可以假冒其他小组生成有效的群签名，所以设计性能良好的门限签名被认为是open问题．该文给出了一种新的适用于(t，n)门限群签名的秘密共享方案称为分组秘密共享方案，群中任意t个成员共享一个秘密，而群秘密是所有组共享秘密的和．基于分组秘密共享方案设计了一类安全的可追查签名者身份的(t，n)门限群签名体制，部分成员合谋无法获得任何系统秘密参数，从而可以抵抗合谋攻击。

A (t,n) Threshold Group Signature Scheme Based on Block Secret Sharing

All of the existing threshold group signature schemes cannot withstand conspiracy attacks. Its reason is that the secret of any subgroup shares is the group secret key , and any t or more group members can cooperate to reveal the group secret key with high probability. Therefore, any subgroup can forge the valid signature stand in other subgroups, the design of an efficient scheme is remained open. A new type of secret sharing scheme called block secret sharing scheme is proposed, in which any t subgroup shares one shadow, and the sum of all of the shadows is the group secret. So any t or more group members cannot cooperate to reveal the group secret key with high probability. A secure ( t,n ) threshold group signature scheme with traceable signers based on block secret sharing scheme is proposed. The feature is that part of members cannot conspire to get any system secret parameters, and cannot forge a valid signature. That is, it can withstand conspiracy attacks.