对一类基于身份的门限代理签名方案的伪造攻击

Forgery Attacks on a Series of ID-based Threshold Proxy Signature Schemes

近来,于义科等人提出了一系列标准模型下基于身份的门限代理签名方案,并以其中最新的于-郑方案作为攻击目标,设计了3个有效的伪造攻击算法。利用这些算法,攻击者可以在得不到原始签名人和任何代理签名人私钥的情况下,仅通过选取随机参数以及多项式时间内的计算,就可达到以显著的成功概率伪造普通签名或任意代理签名人的部分签名的目的。这些伪造攻击算法对于-郑方案及与其同类的其他几个方案都具有有效性。攻击显示,此类基于身份的门限代理签名方案是不安全的。最后分析了方案遭受攻击的原因,并给出了两种可能的改进措施。

Recently, YU Y K et al. proposed a series of ID-based threshold proxy signature in the standard model. This paper constructed three attack algorithms for the latest scheme of YU-ZHENG, with which attacker can forge valid both regular signature on behalf of the original signer and proxy signature of any proxy signer on any message without knowing the signing key of these signers. Our attacking algorithms work well with scheme of YU-ZHENG and the decedent schemes. Attacks show that this series of schemes are unsecure. We analyzed the root cause of attacks and gave some suggestions for modifications in the end.