| dc.description.abstract | Going with the popularity of electronic commerce, the research of electronic payment system is widely developed in recent years. In order to adapt to different transaction environments, several kinds of electronic payment systems are therefore proposed. Micropayment is one of electronic payment systems and applied to the occasions of small value but frequent transactions, such as Internet-based service and commercial activities of digital contents. Due to knowledge exchanging becomes an important application in the future, the research of micropayment plays a critical role in electronic payment system.
At present, many efficient micropayment systems have been proposed. In this thesis, we review required knowledge and some important systems of them. First, the model and participated parties of micropayment are introduced. Afterwards, the requirements of micropayment systems are discussed to help readers realize efficiency and security issues on designing a micropayment system. Three important micropayment systems based on different cryptography primitives are reviewed to illustrate technologies used in micropayment. In the last of this part, comparisons among these systems on three aspects are given. The result shows that anonymity is not presented in these important micropayment systems.
In order to protect privacy, anonymity is extensively concerned by users in electronic payment systems. However, due to the high performance requirement, anonymity is usually ignored in micropayment. The shortcoming reduces user’’s acceptance. In this thesis, a PayWord-based anonymous micropayment is proposed. The proposed system employs a smart card to move signing capability rom the bank to users and decentralizes the overhead of the bank. A spending token is issued with a determined amount limit to control the capability; hence, users make transactions in an authorized credit without the involvement of the bank. The system retains the verification process of PayWord so that it can be applied to other PayWord-based system to provide anonymity. Eventually, a performance comparison is given to show the proposed system is still efficient even anonymity is provided.
In the last part of this thesis, we give some remarks on a PayWord-based multiple shopping micropayment system. PayWord is a vendor-specific payment system, therefore users have to maintain tuples of particular data of chains corresponding to distinct vendors. The multiple shopping system leads a user shopping at several vendors by paying a common hash chain. However, the system has heavier cost than original PayWord both in computation and in storage. Besides, a dispute will happen if either users or vendors misuse the system. We discuss these drawbacks and its reasons in detail. | en_US |