F3B: A Low-Latency Commit-and-Reveal Architecture to Mitigate Blockchain Front-Running

Front-running attacks, which benefit from advanced knowledge of pending transactions, have proliferated in the cryptocurrency space since the emergence of decentralized finance. Front-running causes devastating losses to honest participants$\unicode{x2013}$estimated at \$280M each month$\unicode{x2013}$and endangers the fairness of the ecosystem. We present Flash Freezing Flash Boys (F3B), a blockchain architecture to address front-running attacks by relying on a commit-and-reveal scheme where the contents of transactions are encrypted and later revealed by a decentralized secret-management committee once the underlying consensus layer has committed the transaction. F3B mitigates front-running attacks because an adversary can no longer read the content of a transaction before commitment, thus preventing the adversary from benefiting from advance knowledge of pending transactions. We design F3B to be agnostic to the underlying consensus algorithm and compatible with legacy smart contracts by addressing front-running at the blockchain architecture level. Unlike existing commit-and-reveal approaches, F3B only requires writing data onto the underlying blockchain once, establishing a significant overhead reduction. An exploration of F3B shows that with a secret-management committee consisting of 8 and 128 members, F3B presents between 0.1 and 1.8 seconds of transaction-processing latency, respectively.