关键词: 代理签名 门限签名 原始签名者 代理签名者

Abstract:

Hsu et al proposed a nonrepudiable threshold proxy signature scheme with known signers, and Yang et al pointed out some weaknesses of the scheme and p roposed an improvement scheme with high efficiency. In this paper, we give a cryptanalysis of the Yang et al＇s scheme. Furthermore, we improve the secu urity of the threshold proxy signature scheme which remedies the weaknesses of the Yang et al＇s scheme.

Key words: proxy signature, threshold proxy signature;nonrepudiable