Vitalik Buterin launches the Big FOCIL plan to enhance Ethereum's resistance to centralization

On March 3, Ethereum co-founder Vitalik Buterin proposed the Big FOCIL plan to address the centralization of block builders. This proposal was introduced ahead of Ethereum’s upcoming Glamsterdam upgrade and aims to strengthen censorship resistance and decentralized participation at the protocol level.

Buterin explained that the proposed proposer-builder separation mechanism (ePBS) will separate block proposing from building, allowing builders to compete in a permissionless market while proposers select the best bids. However, a few advanced builders might still gain extra value through transaction ordering optimizations. Big FOCIL extends the forward committed inclusion list (FOCIL), enabling more transactions to be randomly selected by verifiers for inclusion in blocks, thereby increasing fairness and limiting builders’ control over transactions.

Additionally, Buterin highlighted the erosion of user value caused by harmful MEV behaviors, such as sandwich and front-running attacks. He proposed using encrypted mempool technology, where transactions remain encrypted until included in a block, preventing malicious reordering and ensuring transaction fairness. Developers are researching efficient methods to verify and decrypt these transactions promptly, balancing user protection with system performance.

Buterin also discussed transaction entry layer and network anonymization solutions, including Tor routing, Ethereum mixing networks, and Flashnet, aiming to prevent RPC providers or public nodes from observing user transactions, thereby reducing risks of sandwich attacks and other malicious activities. In the long term, Big FOCIL combined with distributed block construction and state synchronization optimizations will reduce reliance on global state, lower centralization risks in execution, and maintain the integrity of Ethereum’s core architecture.

As the Glamsterdam upgrade approaches, Buterin stated that developers will continue to review Big FOCIL and related proposals to ensure Ethereum becomes more decentralized, secure, and to enhance the long-term stability and user experience of the decentralized ecosystem.