REPUTABLE-A Decentralized Reputation System for Blockchain-Based Ecosystems

Reputation systems are an important means to facilitate trustworthy interactions between on-and off-chain services and users. However, contemporary reputation systems are typically dependent on a trusted central authority to preserve privacy of raters or on adding noise into the user feedback. Moreover, the accuracy of reputation values relies on the integrity of user feedback or input; this feedback should not be tampered with or misused for other purposes. This paper presents blockchain-based reputation system named REPUTABLE (A Decentralized Reputation System for blockchain-based Ecosystems), which computes the reputation of service providers and external services within a blockchain ecosystem through decentralized on-chain and off-chain implementation. Specifically, REPUTABLE not only ensures privacy, but also reliability, integrity and accuracy of reputation values, while incurring minimal overhead. It also enables performing certain data or statistical analytics functions on user feedback, whilst preserving security, privacy, accountability and unlinkability of participants and their feedback. We present a proof-of-concept implementation and a demonstration of the REPUTABLE system. Finally, by means of formal and empirical evaluation, we show the effectiveness of our proposed system to preserve the anonymity of user feedback and the high performance of its blockchain-based implementation.