Commit-Reveal$^2$: Randomized Reveal Order Mitigates Last-Revealer Attacks in Commit-Reveal

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.