对几种部分盲签名方案的安全性分析与改进

对张彤等人最近提出的几种基于离散对数的部分盲签名方案进行了安全性分析．发现敌手可在不被察觉的情况下将盲化的消息乘以部分盲因子的逆而成功地去掉该方案中签名的部分盲特性．并且可以伪造签名中的嵌入常数．利用大数分解困难性隐匿张等方案中有限域中生成元的阶，对方案进行了一些改进．新的方案不仅满足部分盲特性要求．并可以防止敌手伪造嵌入参数．同时具备张等方案的其他安全性要求．

Security analysis and improvement of several partial blind signature schemes

The security of several partial blind signature schemes based on the discrete logarithm proposed recently by Zhang et al. is analyzed, and it is found that the adversary can get rid of the partial blind property of the signature without being detected by multiplying the reverse of the partial blind factor to the blind message, and the adversary can forge the embedding parameter in the signature. Then, by using the factoring difficulty and covering the order of the generator of the finite field, the improved partial blind signature schemes not only have the partial blind property but also can withstand the forgery of the embedding parameter, and at the same time they have the same other security requirements as those of the schemes by Zhang et al.