LWB指定验证者签名方案证明的改进

Improved proof for LWB designated verifier signature scheme

针对不可授权的指定验证者签名LWB方案,由于其区分器构造的不合理,在不可伪造性证明过程中,导致其证明不正确的问题,在随机预言机模型下,重新构造了区分器,通过用统计测试的方法计算证明了四元组是Diffie-Hellman四元组的概率和随机四元组的概率,从而达到该区分器的预期目的,并证明在假设DDH问题为难问题的条件下,该方案在选择消息攻击情况下是不可伪造的,从而对LWB指定验证者签名方案的证明进行了改进,确保了该方案是安全可证明的.

For a designated verifier signature scheme （i. e. , LWB scheme） which is shown to be not delegatable, because the construction of distinguisher is unreasonable, its unforgeability proof is not correct. To solve this problem, a distinguisher was reconstructed in the random oracle model, which was used to calculate the probability that a tuple is Diffie-Hellman tuple or that a tuple is random tuple by statistical test, LWB scheme was showed to be unforgeable under chosen message attack based on decisional Diffie- Hellman （DDH） assumption in the random oracle model. And the improved distinguisher and this proof guarantee LWB scheme＇s security.