摘要： 通过对周红生等提出的基于代理签名的多银行电子现金系统进行密码分析，发现在该方案中，中央银行和可信第三方皆可独自冒充其他合法银行签发电子现金。该文利用代理保护型代理签名技术，提出了一种新的基于椭圆曲线的离线多银行电子现金系统。在该电子现金系统中，利用授权书来标明电子现金数的数额，分析表明新方案不仅克服了现有的多银行电子现金系统的不足，而且还具有较好的运行效率。

关键词: 椭圆曲线, 电子现金, 代理签名

Abstract: Through the cryptanalysis of an E-cash system with multiple banks based on proxy signature proposed by Zhou etc., it is found that thecentral bank or the third trustee can issue valid E-cash by imitating other legal banks. An off-line E-cash system with multiple banks based on ellipticcurve is proposed using the technique of proxy-protected proxy signature. The E-cash’s denomination is marked with authorization in this E-cashsystem, and the analysis shows that it overcomes the disadvantages of those existing E-cash systems with multiple banks, and has higher efficiency.

Key words: elliptic curve, E-cash, proxy signature