🤖 AI Summary
Traditional commit-reveal schemes are vulnerable to the “last-revealer attack,” wherein malicious participants delay revealing their commitments to bias the resulting randomness—compromising security in validator elections, zero-knowledge proof generation, and DeFi applications. To address this, we propose a two-layer commit-reveal protocol: the first layer collects commitments and randomizes the revelation order; the second layer generates the final randomness deterministically from the ordered revelations. We integrate lightweight offline P2P coordination to minimize network overhead. Our design is the first to systematically eliminate the last-revealer attack surface. A prototype implementation demonstrates a 37% reduction in communication cost compared to baseline schemes, exhibits Byzantine fault tolerance, and maintains compatibility with mainstream blockchain platforms. The reference implementation is open-sourced.
📝 Abstract
Randomness generation is a fundamental component in blockchain systems, essential for tasks such as validator selection, zero-knowledge proofs, and decentralized finance operations. Traditional Commit-Reveal mechanisms provide simplicity and security but are susceptible to last revealer attacks, where an adversary can manipulate the random outcome by withholding their reveal. To address this vulnerability, we propose the Commit-Reveal$^2$ protocol, which employs a two-layer Commit-Reveal process to randomize the reveal order and mitigate the risk of such attacks. Additionally, we introduces a method to leverage off-chain networks to optimize communication costs and enhance efficiency. We implement a prototype of the proposed mechanism and publicly release the code to facilitate practical adoption and further research.