Abstract: Abstract: The former design of the electronic cash system just pay attention on current safety. However , it put more and more emphasis on consideration of "forward secure” nowadays. The text utilize the mechanism of the master key scheme and rebuilds the eCashTM on-line electronic payment system that have been put in use, and made it be provided with forward secure. After the bank's disclosing private key, the system is able to confine the loss in minimum.

Key words: ecash, master key scheme, forward secure, eCashTM

摘要： 摘 要：以前的电子现金系统设计注重的只是"当前"的安全性考虑。然而，现在的电子现金系统越来越重视“前向安全性”的问题。利用主密钥机制，在不降低效率的情况下，可以对已投入使用的eCashTM在线电子现金系统进行改造，使其具有前向安全性。一旦银行的私钥被泄露，能把损失限制到最小。

关键词: 电子现金, 主密钥机制, 前向安全性, eCashTM