Reusable Off-line Electronic Cash Using Secret Splitting

The idea of electronic cash, as a payment instrument is appealing, but has yet to be widely deployed commercially. We outline the properties of two major approaches to the provision of electronic cash, and discuss their strengths and weaknesses. We then propose a new scheme based on secret splitting that allows for off-line spending of coins with a tailored level of anonymity and allowing reuse of the same coin many times. We then discuss a number of practical issues such as the trade off between coin size and the ability to detect double spending.