A cross-chain rating system: bridging EVM-based blockchains with Chainbridge

Rating systems are services collecting users' opinions about any kind of item, such as movies, locations, or hobbies, typically characterized by centralized governance making them susceptible to censorship or rating manipulation. This paper leverages blockchain technology to build a decentralized system to secure the ratings and operations performed by the users. We assume a scenario where many rating systems coexist and are hosted by different blockchains, and these blockchains are connected with one that could handle monetary-like operations common to the rating systems. The paper describes an experiment with Chainbridge, a tool to perform transfers across two Ethereum-like blockchains, applied to a cross-chain rating system prototype involving two blockchains: one hosting the ratings and one handling the payments. The results include the costs in units of gas and USD, i.e. the blockchain fees, and the latency time to perform a transfer across two test networks, Goerli and Mumbai.