FairTrade: Efficient Atomic Exchange-based Fair Exchange Protocol for Digital Data Trading

Trading of data is increasingly important as data are becoming valuable. This paper studies the fair exchange problem where two untrusting parties need to trade data using digital tokens without anyone being able to cheat the other one. In existing approaches, data are encrypted with some sets of keys, and the keys are traded with digital tokens by leveraging the atomic exchange protocol. There exists a security hole because existing approaches fail to provide a complete and secure design for validating the correctness of the keys. We address this issue by presenting a key verification mechanism that leverages the collision-resistance of hash functions. Additionally, we present a novel atomic exchange protocol based on our key-secret-sharing mechanism, which is more efficient than the existing approach. Our experiments indicate the key verification mechanism incurs negligible overhead and our atomic exchange protocol is more efficient than the state-of-the-art protocol.