带观察器的安全、公正的离线电子现金系统

A Secure and Fair Off-Line E-Cash System with Observers

本文提出了一个带观察器的安全、公正的离线电子现金系统,其特点是将预先防止重复花费机制、部分盲签名机制以及可信第三方的跟踪机制结合起来,使得银行不必使用多个密钥就可以实现电子现金的多面值属性和有效期管理,并且银行只需保留所有未过期的记录,从而大大减少了存储量。与基于Brands方案的系统相比较,该系统中电子现金的不可伪造性和合法用户的匿名性都是可证明安全的。该系统的安全性基于随机Oracle模型和确定性Diffie-Hellman(DDH)问题的难解性。

Three key concepts, which conclude wallets with observers, partially blind signatures and a trusted third party （TTP）, have been proposed in order to attain a practical electronic cash （e-cash） system. In this paper, we incorporate the three primitives to propose an off-line e-cash system. The bank has to neither change his public key to represent a new expiration date, nor use different public keys for different coin values. The stress of storage is alleviated tremendously for the bank＇s only needs to store the valid records which are before their expiration dates. In contrast to the systems which are based on Brands＂ scheme, the unforgeability of e-cash and the anonymity of legitimate users are provably secure. The security of our system is based on random Oracle models and the intractability of the decision Diffie-Hellman oroblem.