Original author: 0X NATALIE
background
More than 90% of Ethereum blocks are generated by MEV-Boost, mainly because its PBS mechanism allows validators to earn more profits. PBS separates the validator from block construction and outsources the behavior of constructing sorting transactions to the builder. The relay acts as the interaction channel between the two. The validator only needs to propose new blocks to the network, so it is also called a proposer. Proposers can earn more revenue by selling block space to block builders, increasing profits. This has prompted more and more validators to join MEV-Boost.
However, the operating costs required to maintain relays can be very high, with estimates ranging from $500,000 to $1 million per year, with zero revenue, leading to vertical integration between builders and relays, affecting relay neutrality . And if relays are factored into the builders costs, the builder would need to make about $3,000 a day to break even. There are currently only three to five builders able to do this, and most of their profits come from private order flow (CEX/DEX arbitrage).
Detailed explanation of MEV-Boost+
EigenLayer believes that the builders are centralized and the proposers in PBS have no transaction power. They are only responsible for selecting the block header with the highest bid from the relay to sign, and then wait for the relay to return the complete block and broadcast it to Verification makes the builders too powerful, and the censorship resistance of the Ethereum network will be unilaterally affected by the builders. Therefore, the MEV-Boost+ mechanism was proposed, aiming to allow proposers to also include transactions.
In PBS, the proposer does not have the power to sort or select transactions, which is a necessary condition to protect the builders MEV from being stolen. So how to protect the builder while allowing the proposer to include transactions? MEV-Boost+ introduces partial block relay to generate a partial block auction mechanism. The proposer can create a part of the block (the rest of the block RoB) and auction the other part (the top of the block ToB). , created by the builder. Additionally, partial block auctions are proposed as an alternative to crLists (censorship-resistant lists) in PBS. MEV-Boost+ is a complementary software to MEV-Boost. MEV-Boost will still handle the entire block auction, and MEV-Boost+ will handle the remaining partial block auctions.
process:
Enrolling: Verifiers must re-stake through EigenLayer to use MEV-Boost+’s partial block relay. Its withdrawal certificate needs to be updated to point to the EigenLayer contract, which contains a Slashing function that can punish the verifier for any malicious behavior.
Proposing: The builder builds the corresponding partial block and then sends it to the MEV-Boost+ relay. The relay will verify the validity of these partial blocks and send the partial blocks transaction Merkle root along with the associated metadata (block number, transaction number, etc.) to the proposer. The proposer will sign the data sent by the relay and send the signed data back to the relay. After the relay verifies the validity of the signature, some blocks are released. The proposer merges the partial block with his own transactions to complete the entire block and proposes the entire block to the network. The atomicity of partial blocks is guaranteed by the proposer, and if the proposer manipulates or changes when building a partial block, the builder does not suffer all the risks associated with the entire block.
Punishment (Slashing): The punishment phase is triggered when the proposers malicious behavior is detected. Any changes to the ToB are considered as the proposers malicious behavior. Observers (relays) can submit fraud proofs indicating that the proposer modified part of the block provided by the builder. If the fraud proof is verified to be accurate, the proposer will be subject to a slashing penalty (32 ETH) through EigenLayers re-staking mechanism. 2 ETH will be allocated to relayers and 30 ETH will be allocated to block builders.
So what are the incentives for proposers and builders to select partial blocks? Needless to say the proposer can include his own transaction, one possible idea: if the proposer detects network censorship pressure and the difference between the partial block bid and the full block bid is less than 0.005 ETH, he will select the partial block and build the rest of the block on its own. Under this setting, the proposer can flexibly choose MEV-Boost (full block) or MEV-Boost+ (partial block). The motivation for builders to build some blocks is to participate in block construction at a lower cost, gain competitive advantages, and at the same time transfer the risk of the atomicity of the block.
Block atomicity emphasizes that multiple operations performed on the blockchain are either all accepted and confirmed, or all rejected, with no intermediate state. The purpose of ensuring block atomicity is to ensure the consistency and security of the blockchain. If a transaction or operation within a block is partially successful, it may result in an inconsistent state, compromising the trustworthiness and integrity of the blockchain.
The MEV-Boost+ mechanism proposed by EigenLayer can balance the power between proposers and builders, bringing more protection to Ethereums censorship resistance. EigenLayers heavy pledge mechanism is used to reduce penalties and ensure the security of the system, while improving financial efficiency to encourage more validators to participate in the ecosystem of Ethereum and other networks, achieving a more decentralized and fair cryptographic world.
