【作者】 肖群；

【导师】 张建中；

【作者基本信息】 陕西师范大学 ， 应用数学， 2004， 硕士

【摘要】 在电子商务活动中，商家、消费者及银行等各方面是通过Internet连接在一起的。电子商务的信息均要通过这样一个开放的网络传递，使网上交易存在各种风险。而电子商务活动发展的最终目标是实现电子商务活动各环节的电子化。电子支付具有方便、快捷、高效、经济的优势，能在很短的时间内完成整个支付过程，支付费用仅相当于传统支付的几十分之一，甚至几百分之一。上网购物采用电子支付是必然趋势。 如何通过电子支付安全快捷地完成整个交易是人们上网购物首先要考虑的问题，因而电子支付是电子商务系统的核心。脱离了电子支付，电子商务无法实现各环节电子化；电子支付的问题处理不好，会使人们对电子商务持观望态度，严重阻碍电子商务的普及和应用，并最终影响电子商务的进一步发展。 如何在现有的基础上提高电子支付的效率、安全性和实用性是电子商务研究的一大热点，其中密码技术是重要的解决手段之一。本文探讨密码学在电子支付中的应用，研究了电子支付协议、电子现金系统和电子支票系统，研究成果如下； 1．本文分析比较了SSL安全协议和SET安全协议，针对SET安全协议的不足，提出了比较具体的改进措施。引入交易认证中心CA将交易数据存放在交易认证中心的数据库中，加强了交易数据的管理安全性。商家和消费者对商品进行了内容、质量等认证，使新协议满足了原子性。公平性是支付协议应具有的性质之一，它使得交易双方处于同等地位。在任一步停止交易双方中任一方不比另一方吃亏，SSL安全协议和SET安全协议都是先付款后发货。本文提出一个新的电子支付协议，将支付命令分为预支付命令和支付命令，先冻结消费者的支付金额，在确定消费者收到加密商品时再划款，较好地实现了公平性，比较适合可在网上直接传递的数字商品的交易。 2．对电子现金的研究状况作了总结，介绍了可分电子现金的发展状况。电子现金的“可分性”是为了解决传统的找赎问题，即将一个大额的电子现金化整为零来实现对用户的找赎。以往的可分电子现金系统由于技术实现复杂，计算量大等原因，难以投入实用阶段。本文中将“可分性”转化为“等额支付”。基于秘密共享技术设计了一个可分电子现金系统，一旦超额支付便可得到共享的秘密——消费者的身份，并将电子现金的金额明确标出，使电子现金像传统现金一样使用方便。在此系统基础上引入可信第三方设计了一个可撤消匿名性的可分电子现金系统，能对电子现金进行向前或向后跟踪。两个电子现金系统中电子现金的序列号由商家给出，只有商家和消费者知道，可防伪造. 3.对电子支票的研究作了介绍、D.C人叨。提出的电子支票系统中电子支票的面值由一些固定的公私钥对来表示，不同面值的电子支票的验证和签发对应不同的公私钥对.电子支票面值越大，计算量越大，效率会被减低.本文对电子支票的面值和有效期取Hash值作为该电子支票的公钥，对应的RSA私钥由银行计算，这样解决了计算量随电子支票面值增大而增大的间题.新的电子支票还可让在乎利息的用户和商家可以协商交易金额存入商家帐户的时间，且可根据情况灵活改动该时间.对于到期未花费掉的电子支票可进行汇兑到持有者的帐户或更换新的电子支票，并对新的电子支票系统作了安全性分析.更多还原

【Abstract】 It is Internet through which all traders, customers and banks are connected with each other for e-commerce activities. All information for e-commerce is transferred in such open network that may bring various risks to the online business, whereas it is a final aim of e-commerce development that to realize a whole electronical process with every electronical steps. Electronic payment possesses advantages as being convenient, rapid, highly efficient and economical as well, which enable the whole payment process to be accomplished in a very short time. Meanwhile it charges only several tenths or even hundredths compared to that of traditional payment. Electronic payment turns to be a due tendency of online shopping. How to accomplish the transaction safely and quickly, this has become a question that people would firstly consider before they choose online shopping, which, also pushes e-payment to become the core of e-commerce. Deviated from e-payment, no real electronic process will be realized for e-commerce; without appropriate solutions to e-payment, no outlook of e-commerce could be expected by people, furthermore, it could even stunt realization and popularization of e-commerce, bringing very negative effect against further development of e-commerce.How to enhance the efficiency, security and practicability of e-payment based on its current status has become one of the hottest topics in e-commerce research, among which cryptography stands as one of the important solutions to this problem. This paper is intended to discuss the use of cryptography in e-payment and it is designed for deeper research against e-payment protocols, e-cash systems and e-check systems with the main achieved points as given below:1. This paper analyses and compares SSL and SET from all aspects, including analysis on deficiency of SET and further to lay out detailed suggestions for its improvement. CA imports and saves the transaction record into its database, enhancing security of transaction record management. Traders and consumers’ identification against commodities quality and aspect etc satisfies the atomicity of new protocol. Fairness is one of the basic natures for payment protocol, which equalizes roles of both parties in trade activities and allows termination at any step in transaction that would not affect benefit of either party. SSL and SET shares the same payment term as payment first and delivery second. This paper brings forward a new payment protocol, diversifying paymentslip into requestslip and paymentslip. By initially freezing the payment value of consumer and thentransferring upon receival of encrypted commodities confirmed by consumer, the fairness is well realized and it is suitable for digital commodities and commodities which could be directly transacted through Internet.2. A survey on e-cash system is given and the paper presents an introduction of the status of divisible e-cash development. The divisibility of e-cash is used to address the traditional problem of change in a trade, that is, to break up a big coin into parts to accomplish payment. Early divisible e-cash system turned to be unfeasible due to difficulties of complicated technology realization and heavy calculation duty. This paper transforms "divisibility " into "equal-value payment" and designs a divisible e-cash system based on verifiable secret sharing scheme. E-cash is divided into several equally valued sub-coins for payment . Once payment excess happens, the shared secret information is obtained - identification of consumer.lt enables e-cash to be convenient in use as well as traditional cash by clear markings on its value.Also based on this system, a trusted third party (TTP) is imported and designs an anonymity-revocable divisible e-cash system , it can trace owner and coin both. Serial number of e-cash is provided by the traders and is known by traders and consumers both only, which, acts as being anti-fake .3. The paper also lays out instruction of e-check research. In e-check system submitted by D.Chaum, e-check value更多还原