Security enhancement of a flexible payment scheme and its role-based access control

Abstract

Recently, Wang, Cao, and Zhang proposed a practical and anonymous payment scheme. In the scheme, the authors claimed that their scheme can identify those who spend a coin more than once. That means the scheme can verify the payments in an offline batch process and prevent a consumer from double spending. In this paper, we show that Wang, Cao, and Zhang's scheme can not identify consumers those who spend the same coin repeatedly in two or more different shops at the same time. So, all consumers can apply the security flaw to perform double spending successfully. In order to overcome this security flaw, we provide an improved version of the scheme in this paper. © 2008 Springer-Verlag Berlin Heidelberg.