Electronic cash analysis on fair traceability, double spending prevention and model simplification

Abstract

Electronic cash is an electronic payment system which enables secure payment transactions without revealing customers' identity. This thesis starts with an overview of the concepts related to electronic payment, especially electronic cash, discussing its transactions and state-of-the-art techniques. Then, after an overview of electronic cash, I will analyze several electronic cash schemes against potential attacks. In this thesis, I will propose O-Cash, the fair traceable electronic cash in wallet with observers, which supports coin tracing and owner tracing as well as self-deanonymization. This scheme achieves prior restraint of double-spending using observers, detection of double-spender's identity using cryptographic methods in case observers are broken, and fair tracing in case crimes take place. Then, I will further propose a new electronic cash model SignCash, where electronic coins are generated by customers instead of banks. This model offers unique tradeoff between credit card systems and conventional off-line electronic cash systems, and provides anonymity to customers and higher security level than credit card systems. In addition, it enables customers to generate electronic coins which are authorized by the bank, and is more convenient for customers to use. Last but not least, I will compare the proposed electronic cash system with VisaCash and eNETS, and discuss the implementation aspects.