高效的离线电子现金方案

电子现金本质上是一串容易被复制的比特序列，如何在保护合法用户匿名性的前提下有效地防止其被重复花费是电子现金研究的关键。提出了一种新的基于RSA盲签名的离线电子现金方案，采用双密钥对称加密，将用户账号信息嵌入其中，从而保证合法花费一次用户的匿名性，也能够以极大的概率找出重复使用同一笔电子现金的用户。对分割选择（cutandchoose）机制进行了改进，降低了计算复杂度。最后，对方案的公平性和安全性进行了分析。

Efficient off-line E-cash scheme

E-cash is essentially a string of bit sequence,which is easy to be copied.The key concern of E-cash is how to effectively prevent E-cash from being double-spent under preconditions that a legal user's anonymity is well protected.An off-line E-cash scheme basedon RSA blind signature is presented.The technology oftwi-symmetrical encryptionemploying double keys is adopted.It guarantees anonymity of theusers who spend an E-cashpiece onlyonce.Besides,the userwho has spent thesamepiece of E-cash twiceare detected at a considerable probability.The cut and choose scheme is improved to decrease computing.Finally,the analysis of security and the demonstration of fairness are given.