PayStar: A denomination flexible micropayment scheme

In this paper, the PayStar micropayment scheme with the property of flexible coin denomination is proposed. In practice each purchase may require a different amount of payment even in the scenario of micropayment applications and the proposed flexibility of denomination is therefore practical. Our design primarily intends to improve the performance of the customer's side since small portable devices are usually employed. The proposed PayStar improves drastically the computational performance of the customer from the viewpoint of processing each smallest denomination, e.g., one cent, due to the nature of PayStar which divides one lengthy conventional payment chain into a bundle of short merged one-way chains. Computational performance of the merchant has been improved as well. In PayStar scheme, storage cost of the customer is extremely low, the customer only needs to store one secret value for each PayStar token and it is thus suitable for implementations on small portable devices.