We provided a scalable and resilient access control scheme based only on hash functions, presented applications to electronic payment, and gave a discussion of the scheme. Since this scheme does not share the customer's secret with either the bank or the merchant, we can develop privacy-enhanced and customer-oriented transactions. As the scheme does not deploy a large public key infrastructure, the implementation cost can be lower than conventional schemes such as SET [VM97]. Our scheme can be applied to the existing payment infrastructure with a minimum of change.
We consider applications of our scheme. Paper-based payments using a cheque are still popular, but expensive for banks to process. An on-line electronic cheque can be a system that transfers funds from the payer's bank account to the payee's bank account at the time the transaction takes place. Our scheme is also applicable here, by replacing the merchant with the payee with suitable modifications. One can also consider sophisticated off-line features such as deferred payment, bouncing cheques, etc. Electronic cheque transactions are a topic of future work.