对YTH门限代理签名方案的分析与改进

Cryptanalysis and improvement of YTH threshold proxy signature scheme

目的分析YANG,TZENG和HWANG2004年提出的门限代理签名方案(简称YTH方案)。方法利用有限域上离散对数困难问题和安全单向哈希函数对原方案进行改进。结果分析YTH方案发现该方案是不安全的,容易受到公钥替换攻击,故提出了一种新的安全高效的门限代理盲签名方案。结论新方案不仅避免了公钥替换攻击,而且还具有不可否认性和不可伪造性等安全门限代理签名和盲签名所具有的性质。

Aim The security of YTH scheme, which was proposed by YANG C Y, TZENG S F and HWANG M S in 2004 was analyzed. Methods The original scheme was improved on the basis of the discrete logarithm problem and the secure one-way Hash function in finite field. Results Through analyzing the security of YTH scheme, The scheme was found to be vulnerable to public-key substitute attack. A new blind threshold proxy signature scheme with high safety and efficiency is proposed. Conclusion The improved scheme can not only avoid public-key substitute attack, but also has such properties threshold proxy signature and blind signature should have as unforgeability, non- repudiation.