探讨Chang等提出的面向群通信的(t,n)门限签名(k,l)门限验证的数字签名方案.分析认为,由于方案不需要分发中心(SDC),任何t个参与者可以代替一个群(签名群)对一个信息签名,并且任何女个参与者可代替另外一个群(验证群)对签名进行验证,因此,不能抵抗假冒攻击.
Recently, Chang proposed a (t,n) threshold signature with (k,l) threshold-shared verification to be used in agroup-oriented cryptosystem without a shared distribution center (SDC). In their scheme, any t participants can represent a group (signing group) to sign a message,and any k participants can represent another group (verifying group) to verify the signature. In this paper, we will argue that Chang's scheme is vulnerable to the impersonation attack, and violates the basic definition requirement of (t,n) threshold signature with (k,l) threshold-shared verification.