关键词: 门限签名, 门限密码学, 分组秘密共享, 合谋攻击

Abstract: Threshold signature is a special digital signature, and it is in popular use. A out of threshold signature scheme is a protocol that only or more than the threshold number group members can generate a valid signature, while fewer than players cannot create a valid signature in the protocol. But most of the recent protocols cannot withstand conspiracy attacks. In other words, in most of protocols, some subgroups of or more than players can easily get any secret parameters of the system, so any subgroups of players can forge any valid signature in place of other subgroups. In this paper, we introduce two methods to withstand conspiracy attacks: when and are not very large, we present an efficient threshold signature scheme. Furthermore we also introduce a kind of method that can be applied in any threshold signature schemes so that the resulting scheme can withstand conspiracy attacks when and are large.

Key words: threshold signature, threshold cryptography, block secret sharing, conspiracy attacks, RSA