Security analysis of a digital multisignature scheme
一种多重数字签名方案的安全性分析

Lu et al.pointed out that there is the same weakness in the multisignature scheme proposed by Hurn and proposed by Ji et al.,that is,several members collude together,they can deny that they had taken part in process of signing some messages with others.To avoid this weakness,Lu et al.proposed improvements for the two multisignature schemes.In this paper,we first analyzed The scheme improved by Lu et al was analyzed.And showed that their scheme was still insecure,then a new multisignature scheme was proposed.The scheme propose not only can withstand the collude attack,but also has the property of forward secure.An adversary can not forge multisignature pertaining to the past even if has gotten the current all signatures'keys,that is,previous generated multisignature remains valid.