Fair and abuse-free contract signing protocol supporting fair license reselling

Most of the fair contract signing protocols published to date make use of a Trusted Third Party (TTP) to achieve fairness. In this paper, we have designed a fair contract signing protocol to support fair reselling of a DRM license without using a dedicated TTP. This protocol makes use of the concurrent signature (CS) and the existing license distribution infrastructure. By making use of the CS scheme, and integrating it into the existing license distribution infrastructure, we avoid the use of a dedicated TTP, thus introducing no additional communication overhead in providing fair license reselling. Also, the protocol is designed such that none of the two signers can prove to an outside entity that he is in control of the outcome of the protocol, thus achieving abuse-freeness