Abstract:  With the rapid development of the network, the scale of e-commerce is getting bigger and bigger. Electronic cash (e-cash) is an important payment method to e-commerce and attracts a lot of scholars at home and abroad to study it and design a conditional, divisible, transferable or multi-bank e-cash protocol. How to design a safe e-cash protocol with various characteristics is a very important research topic. This paper firstly introduces the basic model of the e-cash protocol. Secondly, this paper introduces the definition, development status and existing problems of the e-cash protocol from various characteristics and gives the application of the e-cash protocol. Thirdly, the important cryptographic primitives are given to construct the e-cash protocol and the provable security theory is described to prove the security of the e-cash protocol. Finally, the problems of the e-cash protocol are summarized and the latest research direction is given.

Key words: e-commerce, e-cash scheme, standard model, zero-knowledge proofs, anonymity, blockchain

摘要： 随着互联网的快速发展，电子商务的规模越来越大，电子现金（e-cash）作为电子商务的一种重要支付方式，吸引了国内外很多学者对其进行研究，并设计出具有条件性、可分性、可传递性和多银行性的电子现金协议，因此如何设计出安全的具有各个特性的电子现金协议是一个非常重要的研究课题。介绍了电子现金协议的基本模型；从电子现金协议的四个特性出发，介绍了具有各个特性电子现金协议的定义、发展现状和存在问题，并给出每个特性在电子现金协议中的应用场景；分析了构造电子现金协议所需要的重要的密码学原语，以及证明了电子现金协议安全的可证明安全理论；最后综述了电子现金协议存在的问题，同时探讨了电子现金协议的最新研究方向。

关键词: 电子商务, 电子现金协议, 标准模型, 零知识证明, 匿名性, 区块链