Privacy-Preserving Reputation Systems Based on Blockchain and Other Cryptographic Building Blocks: A Survey

Abstract

The purpose of a reputation system is to hold the users of a distributed application accountable for their behavior. The reputation of a user is computed as an aggregate of the feedback provided by fellow users in the system. Truthful feedback is clearly a prerequisite for computing a reputation score that accurately represents the behavior of a user. However, it has been observed that users can hesitate in providing truthful feedback because, for example, of fear of retaliation. Privacy-preserving reputation systems enable users to provide feedback in a private and thus uninhibited manner. In this survey, we propose analysis frameworks for privacy-preserving reputation systems. We use these analysis frameworks to review and compare the existing approaches. Emphasis is placed on blockchain-based systems as they are a recent significant development in the area. Blockchain-based privacy-preserving reputation systems have properties, such as trustlessness, transparency, and immutability, which prior systems do not have. Our analysis provides several insights and directions for future research. These include leveraging blockchain to its full potential in order to develop truly trustless systems, to achieve some important security properties, and to include defenses against common attacks that have so far not been addressed by most current systems.

On the Malleability of Consumer Attitudes toward Disruptive Technologies: A Pilot Study of Cryptocurrencies

“…Cryptocurrencies are often seen as an investment instrument, and financial gains are a major motivator for buying and trading them. Taken together, their perceived attributes create a level of (perceived) risk that ultimately depends on an individual's personal assessment [1,2,[18][19][20].…”

REPUTABLE–A Decentralized Reputation System for Blockchain-Based Ecosystems

“…Several reputation systems have been proposed for different security settings. Hasan et al [11] provided a comprehensive survey and evaluations of different privacy-preserving reputation systems. Pavlov et al [12] proposed a secure multi-party aggregation model for aggregating the reputation scores from the participants in a malicious and honest but curious model.…”

Feasibility of Proof of Authority as a Consensus Protocol Model

“…1. Liveliness of the Network: As the framework of PoA depends on the reputation of the sealer hence the liveliness of the network implies that the reputation system of the network does not provide a possibility to reach a state at which the bad behaviour of the sealer no longer damages their reputation [9].…”

“…3. Monotonicity: The reputation system associated with the PoA framework should not be monotonic in nature in any one direction as it will decrease the trust factor of the network [9].…”