Untraceable off-line electronic cash flow in e-commerce

Electronic cash has been playing an important role in electronic commerce. One of the desirable characteristics is its traceability, which can prevent money laundering and can find the destination of suspicious withdrawals. The authors develop a new scheme for untraceable electronic cash, in which the bank involvement in the payment transaction between a user and a receiver is eliminated. The user withdraws electronic “coins” from the bank and uses them to pay to a receiver. The receiver subsequently deposits the coins back to the bank. In the process, the user remains anonymous, unless s/he spends a single coin more than once (double spend). The security of the system is based on DLA (Discrete Logarithm Assumption) and the cut-and-choose methodology