Ethereum co-founder Vitalik Buterin has identified the implementation of fork-choice enforced inclusion lists (FOCIL), an Ethereum improvement proposal (EIP-7805), as one of the key ways to ensure the network is neutral and censorship-resistant.
Buterin shared this view on X while contributing to the debate on whether FOCIL is crucial for Ethereum. According to him, the neutrality feature of the Ethereum mainnet is so important that there should be several measures to ensure it is not infringed.
He said:
“I think neutrality / “dumb pipe” property of the L1 is important enough that we should have multiple lines of defense to protect it.”
Buterin highlighted some of those measures, including ensuring that the public mempool remains strong and viable for building blocks naively and working on other distributed block building technology.
He added that there should also be extra channels that will allow inclusion of transactions, such that even when Ethereum staking becomes centralized, centralized validators cannot censor transactions. He noted that FOCIL can be one of those extra channels.
The Ethereum co-founder went ahead and explained how FOCIL works. According to him, the best way to understand it is to see it as a way to expand the number of proposers per slot from just one to 17. He stated that one of the 17 proposers would be privileged to move last and choose transaction order.
However, transactions proposed by any of the 17 proposers must be included, with the other 16 proposers serving as attestors. This ensures that the other 16 non-privileged proposers have a much lighter weight.
He explained:
“They do not need to calculate the state root, they only need to compute the validation part of any transaction, they can even be stateless, so even at much higher gas limits it’s viable for any attester to also be one of these “auxiliary proposers.”
Buterin concluded that the goal of FOCIL is to prevent any block builder from having the power to veto a transaction inclusion. He envisaged a future where the same property could be extended to smart contract wallets and privacy protocol withdrawals, limiting centralized dependency.
Reflexer Labs executive warns about the risk of FOCIL
Meanwhile, not everyone within the Ethereum community is sold on FOCIL like Buterin. Reflexer Labs co-founder Ameen Soleimani disagreed with the idea, noting that it creates a big problem and failure to see the potential issues is either “naive or reckless.”
In his opinion, Ethereum’s current censorship resistance model has worked by making staking permissionless and allowing stakers to decide which transactions they want to include. He noted that even if 99% of staking nodes decide to censor Tornado Cash transactions, the transaction will still go through, only that it would be 100x longer than usual.
Thus, he believes this model already gives node operators in countries such as the US the opportunity to filter out sanctioned addresses and avoid the associated legal risks of processing sanctioned transactions, while validators in other countries can still process such transactions.
Soleimani also believes the risks of the oligopoly of block builders might be over-exaggerated, noting that transactions from sanctioned addresses are still being processed on Ethereum.
He said:
“Even with the block builder oligopoly, only 2 out of 3 of the block builders are censoring, and as the OP mentioned, 90% of the rest of the validator set is NOT engaging in censorship.”
However, he warned that FOCIL will force validators to include transactions from sanctioned addresses, which could open them up to legal liability. Although he acknowledges that the plan seeks to distribute the responsibility to other validators who are not chosen for the block, he does not believe that will stop authorities from coming after validators.
As he noted, the US government could go after validators even with their diminished responsibility, go after the attesters who included transactions from sanctioned addresses in a block, or even prosecute Ethereum core developers who designed FOCIL. Soleimani referenced the prosecution of Tornado Cash developers.
Instead of FOCIL, Soleimani believes Ethereum should stick with the current system, which relies on attesters who are altruistic enough to include transactions from sanctioned addresses into Ethereum blocks. He added that active research is still ongoing on other censorship-resistant mechanisms that could be implemented.
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