Abstract: Compared with physical cash, electronic cash processes many more advantages, but its reusability is paid less attention to. Developing reusable e-cash can not only improve efficiency and performance, but also enhance anonymity and untracability, thus processing more practical importance. Hitesh Tewari et al. proposed such a scheme using secret splitting, but with some disadvantages: (1) Anonymity gets compromised due to identity information in the scheme; (2) Cash will grow longer and longer along with their use, so there must be limitations on times; (3) Double spending won't be detected untill cash is deposited. In this paper, we propose a new scheme for reusable e-cash, which simulates the process of physical cash, and guarantees customers' control of their e-cash and handovers the ownership of e-cash when paying. Our scheme realizes the reusability in a perferable way, and has better secruity and usability.

Key words: reusability, e-cash, authorization