dBFT Enhancement

Neo X's enhanced Delegated Byzantine Fault Tolerance (dBFT) introduces a PreCommit phase to enforce fair transaction ordering and eliminate MEV risks.

Consensus Flow with Envelopes

1. Proposal and ordering phase

   • Envelope transactions are proposed as same as normal transactions in PrepareRequest.

   • Transactions are ordered based on their gas price, thus Envelope transactions often be placed at the front due to additional decryption fees.

   • By the end of PrepareResponse, a PreBlock for the next block height is confirmed, finalizing the transaction order before decryption occurs. This prevents malicious reordering based on MEV insights.

2. Decryption phase

   • During the new PreCommit period, consensus nodes (CNs) identify Envelope transactions and broadcast decryption shares for them.

   • Once at least $2f+1$ decryption shares are collected, the Envelope transactions are replaced with their decrypted inner transactions in the proposed block.

   • No view changes occur after this stage, ensuring decrypted transactions remain protected from MEV-based manipulation.

3. Commitment phase

   • CNs compute and broadcast signature shares for the finalized block proposal.

   • The block is committed and acknowledged by the network only when at least $2f+1$ signature shares are collected.

   • The final block includes decrypted transactions instead of Envelopes, ensuring a transparent and MEV-resistant execution.

Conclusion

Neo X's Anti-MEV solution provides a robust mechanism to protect users from MEV attacks. By integrating threshold encryption, decentralized key generation, and enhanced dBFT consensus, it ensures fair transaction ordering and confidentiality.