Cryptanalysis of a Threshold Proxy Signature with Known Signers

破密－已知簽署者名單的門檻式代理簽章協定

楊伏夷(Fuw-Yi Yang)

《建國科大學報》 25卷1期 (2005/10) Pp. 55-62

https://doi.org/10.6995/JCTU.200510.0055

摘要

(t，n)門檻式簽章協定容許群體（總共n個簽署個體）中的部份個體（t個簽署個體，t≤n）共同產生電子簽章的能力；若加入代理簽章的性能則稱為“門檻式代理簽章協定”；若此電子簽章伴隨簽署個體的驗證名單，則稱為“已知簽署者名單的門檻式代理簽章協定”。Hwang et al.於2000年提出這樣的一個簽章協定；不久之後，Tzeng et al.於2004年指出Hwang et al.的簽章協定在安全方面有破綻，並且加以改善。本文討論這兩個簽章協定的安全性能，並且證明它們具有共同的安全漏洞。

關鍵字

門檻式簽章協定 ； 數位簽章 ； 代理簽章

並列摘要

A scheme of threshold proxy signature with known signers was proposed by Hwang et al. In their scheme, the receiver can identify the proxy signers that actually generated proxy signatures. Tzeng et al. demonstrated that this signature scheme is insecure and proposed an improvement to mend the information leakage. This paper shows that the improved scheme is still insecure under the original signer's forgery attack, i.e. insider attack. Our demonstration of insider attack shows that the original signer can freely choose message and delegation warrant and then produces a signature on them.

並列關鍵字

Digital signature ； non-repudiation ； proxy signature ； threshold proxy signature