关于Okamoto盲签名方案与部分盲签名方案的安全分析

Cryptanalysis of Okamoto Blind Signature Scheme and Partially Blind Signature Scheme

Okamoto在无随机预言机模型下提出一个签名方案和它的变型,并且在此基础上构造出了在无随机预言机模型下的盲签名方案与部分盲签名方案。然而,本文首先证明其变型的方案是不安全的,然后证明其盲签名方案与部分盲签名方案在任何用户不用询问签名预言机就能伪造任何消息的签名。

Recently,Okamoto proposed a signature scheme without random oracles and its variant,and then constructed a blind signature scheme and a partially blind signature scheme without random oracles based on the variant scheme.He also provided security proof for each signature scheme.However,in this paper,the author shows that the variant scheme and the（partially）blind signature scheme are not all secure,anyone who do not query the signing oracle can forge signature of any message.