Fair electronic cash withdrawal and change return for wireless networks
Robert Tracz, Konrad Wrona · 2001
We propose a practical mobile electronic cash system that combines macro and micropayment mechanisms and offers very high security and user's privacy protection. Notably, we have developed an innovative fair withdrawal and change return protocols, which are efficient and preclude any fraudulent misbehaviors, while user anonymity and transaction unlinkability are preserved. Coins are withdrawn if, and only if payer's account is debited. Change is returned to an anonymous payer, who gets it always but only if she is entitled to receive it. Wiretapping of even all channels does not yield a valid coin, and a payment can not be deposited at the account of another payee. Lost or stolen coins are blacklisted immediately and their value is recovered. No cooperation of dishonest participants gives any advantage. A prototype implementation proved that the system is efficient and convenient.