论文标题:电子现金安全支付系统的研究与实现
Research Correlated to Ni-like Ag X-ray Laser Experiment
论文作者 喻镝
论文导师 张益新,论文学位 硕士,论文专业 计算机应用技术
论文单位 广东工业大学,点击次数 88,论文页数 77页File Size1879k
2001-03-02论文网 http://www.lw23.com/lunwen_731187712/ 电子商务；电子现金；可分性问题：身份认证
E-Commerce, E-cash, Divisibility problem, User Authentication
电子现金是一种新型的电子支付方式，它具有保护用户支付行为隐蔽性，防止拒绝支付和透支行为等诸多优点，它作为纸币的电子等价物已完全可能具备货币的五种基本功能，即价值量度、流通手段、储蓄手段、支付手段和世界货币，它可通过网络系统和公共信息平台实现流通、存取、支付。它的出现将极大地推动了电子商务的发展。 本文提出一种电子现金安全支付系统的解决方案，主要解决往常电子现金系统中较难解决的问题：“可分性”问题，并力求使系统的效率较高。 本论文先从概要介绍了电子货币，在此基础上对电子现金的研究现状做了一个较为全面的介绍。接着阐述本文建立的一个安全有效的电子现金系统。该系统是建立在Brands方案基础之上（Brands方案被认为是当前效率最高的电子现金方案之一），并提出了一种基于EIGamal数字签名的认证方案，该认证方案是对一种EIGamal数字签名认证方案的改进，通过消除上述方案中的逆运算，在确保安全性的前提下，实现了本认证方案的高效性。此外，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。而在本文中却将“可分性”问题转化为“等额支付”问题，即在用户取款时取出大量的的面额不等的电子现金，支付时以这些电子现金的子集来完成等额支付。如何求得最优化的电子现金集合以及如何用该集合来完成支付是解决“可分性”问题的关键。解决上述两问题的方法分别是N—分割算法和贪婪支付算法，本文分别按面额不受限制和面额受限制两种情况来讨论，还分别证明了上述两算法的可行性和最优性。
E-cash is a new electronic payment mechanism, which has many advantages, such as protecting anonymity of user, keeping from ceasing to pay and overdraft. As an electronic equivalent of paper currency, it has five basic functions which are measurement of value, means of circulation, means of store, means of payment, general currency. E-cash can be circulated, deposited and withdrawed through Internet or public information flat. Its emergence will contribute greatly to development of Electronic Bussiness. This thesis presents a solution scheme of e-cash system. It focuses on solving some comparatively difficult problems in e-cash system: divisibility problem , and strives to improve the system efficiency. First the thesis introduces e-currency in the mass. Based on such subject it introduces research status of e-cash. In succession it describes a secure and efficient e-cash system. This system is a modification one coming from Brands scheme (Brands scheme is considered as one of the most efficient e-cash scheme), and it uses a certification scheme based on ElGamal digital signature. The certification scheme is an advanced one of a previous scheme based on ElGamal digital signature as inverse operations eliminated and is efficient with high security. In the addition, 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. However, this thesis transforms divisibility problem to exact payment problem which means that a user withdraws many coins of different denominations during withdrawal period, then uses a subset of these coins to provide the extra payment during payment period. How to get the optimal set of coins and how to accomplish payment with the set are the keys to solve the divisibility problem. The solution of above two problems is using greedy payment algorithm and N-divisibility algorithm. By discussing them in two situations such as being unlimited and being limited in denomination, it proves above two algorithm feasibility and efficiency respectively.
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