An efficient fair payment protocol in mobile DRM

The presented mobile DRM are short of an efficient payment protocol to guarantee that participants can engage in the exchange without the risk of suffering a disadvantage. Even the latest DRM standard of the Open Mobile Alliance (OMA) did not give a detailed transaction scheme in mobile DRM. In general, the fair payment approaches in mobile DRM rely on the service of an external trusted third party (TTP) or add the fees to the phone bill which renders the TTP a bottleneck or just adapts to micro-billing. Therefore, referring to the architecture of OMA DRM, in this article we present a practical fair payment protocol in mobile DRM without TTP by using the concurrent signature scheme. In this protocol, the keystone embedded in the input of protocol by the customer, and if not revealed, the protocol has the deniability; otherwise the transcript of protocol is binding for the identification. So, it reduces the cost of all parties' computation and decreases the communication passes. This protocol is analyzed and compared with other payment protocols used in mobile DRM, the results show that the proposed payment protocol satisfies the requirements of the fair e-transaction and its communication cost and customer's computation are reduced significantly.