FileBounty: Fair Data Exchange
This addresses the need for secure peer-to-peer data sales without central intermediaries, though it is incremental as it builds on existing cryptographic and blockchain concepts.
The authors tackled the problem of trust in centralized online data marketplaces by introducing FileBounty, a fair protocol that enables trust-free data exchange with integrity guarantees, requiring only three on-chain transactions for honest participants.
Digital contents are typically sold online through centralized and custodian marketplaces, which requires the trading partners to trust a central entity. We present FileBounty, a fair protocol which, assuming the cryptographic hash of the file of interest is known to the buyer, is trust-free and lets a buyer purchase data for a previously agreed monetary amount, while guaranteeing the integrity of the contents. To prevent misbehavior, FileBounty guarantees that any deviation from the expected participants' behavior results in a negative financial payoff; i.e. we show that honest behavior corresponds to a subgame perfect Nash equilibrium. Our novel deposit refunding scheme is resistant to extortion attacks under rational adversaries. If buyer and seller behave honestly, FileBounty's execution requires only three on-chain transactions, while the actual data is exchanged off-chain in an efficient and privacy-preserving manner. We moreover show how FileBounty enables a flexible peer-to-peer setting where multiple parties fairly sell a file to a buyer.