Managing Reputation Scores in a Blockchain-based Decentralized Marketplace

The goal of a trust and reputation system is to provide buyers with a robust framework that allows them to select a seller based on accumulated evidence of the seller’s past behavior in the marketplace. The quality of such a trust and reputation system depends on the quality of the feedback provided by buyers. Being a subjective measure, the quality of buyer feedback is notoriously hard to assess. When feedback is provided by buyers from around the world, who may value different aspects of the same transaction differently, it is very hard to know when a buyer provides truthful feedback.In this work we assume a blockchain-based decentralized marketplace where a Smart Contract is associated with each transaction. In an attempt to reduce the uncertainty associated with buyer feedback, the novelty that we introduce in this work is that at the end of the transaction, the Smart Contract is responsible for providing feedback, replacing notoriously unreliable buyer feedback by a more objective assessment of how well the buyer and the seller have fulfilled their contractual obligations towards each other. While Smart Contracts are naturally associated with transactions, to the best of our knowledge, this is the first time Smart Contracts are empowered with providing transaction feedback.Our second main contribution is to show how to manage efficiently reputation scores in such a blockchain-based marketplace.