Shutter Network Proposes “Holy Trinity” to Combat Ethereum’s Rising Censorship and Centralization

May 23 – Shutter Network an open-source threshold encryption protocol initially developed by brainbot GmbH and contributor to Gnosis Chain’s encrypted transaction layer, has proposed a three-part solution that has each been discussed independently in the Ethereum ecosystem, but never fully integrated. This strategy, coined the “Holy Trinity of Censorship Resistance” by Marc Harvey-Hill from Nethermind, combines three key technologies: enshrined PBS (ePBS), FOCIL (Fork-Choice enforced Inclusion List), and encrypted mempools. The proposal outlines how a combination of protocol upgrades could restore the neutrality and trustworthiness that have long defined Ethereum’s core ethos.

With just two builders responsible for more than 80% of block production, Ethereum’s transaction flow is increasingly controlled by a small set of actors. This concentration of power is undermining the network’s goals of open access, credible neutrality, and resistance to manipulation, especially as Ethereum evolves into a settlement layer for high-stakes applications like stablecoins and tokenized real-world assets.

“Censorship resistance isn’t just a philosophical ideal but a technical necessity,” said Loring Harkness, Head of Commercial at brainbot GmbH. “As Ethereum scales into mainstream financial infrastructure, the ability to guarantee neutral, reliable transaction inclusion is what will distinguish it from centralized alternatives.”

The Three-Part Proposal: 

1. Enshrined PBS (ePBS): Eliminating Trusted Relays

Out-of-protocol PBS currently relies on relays to mediate between proposers and builders, making them centralized choke points. In this system, relays receive blocks from builders and forward headers to proposers, who then sign and return the selected header. While effective, it introduces trust and censorship risks.

Enshrined PBS  proposes removing these intermediaries by implementing PBS directly in Ethereum’s consensus layer. Builders submit a hash of the block payload; if the beacon block referencing it gains enough attestations, the payload is released, and validators confirm it was delivered on time. However, ePBS doesn’t resolve builder centralization or malicious MEV extraction – hence the need for the next two components.

2. Fork-Choice enforced Inclusion List (FOCIL): The Watchdog Against Censorship

EIP-7805 introduced the concept of FOCIL, where validators select an Inclusion List (IL) committee per slot. Each member of the IL committee  compiles a list of pending transactions from the public mempool, which are then merged and must be included in the block by the proposer. Attesters only validate blocks that comply.

This system ensures censored transactions still have a guaranteed path to inclusion, assuming at least one honest IL committee member. It enforces accountability at the block production level and makes censorship visible and punishable.

3. Encrypted Mempools: Leveling the Playing Field

Encrypted mempools prevent frontrunning and MEV extraction by hiding transaction contents until block inclusion is confirmed. Highlighted by Vitalik Buterin as a key future upgrade, this system creates fairness by keeping transaction data private until it’s too late for manipulators to exploit.

Shutter recently proposed a practical roadmap for a threshold encrypted mempool on Ethereum L1, leveraging Shutter and proposer commitments to make this system viable within Ethereum’s current architecture. Shutter has already deployed its encrypted mempool on the Gnosis Chain using a threshold encryption scheme and has proposed a phased path to Ethereum mainnet integration.

A Coordinated Execution Model

In a network using ePBS, FOCIL, and encrypted mempools, users submit encrypted transactions to the public mempool. The IL committee selects transactions for mandatory inclusion. The mempool provider then releases the necessary decryption material, which upon receiving sufficient attestations are used by the Builder for decryption.If valid transactions are omitted despite available gas, the block is invalid. If decryption is delayed, transactions roll into the next slot—ensuring inclusion, privacy, and fairness even in adversarial conditions.

Shutter outlined the potential transaction flow in a network that implements ePBS, FOCIL, and an encrypted mempool:

Users submit encrypted transactions using a public key from the mempool provider. An IL committee monitors the mempool and builds inclusion lists, which the proposer merges into a single list. The builder must include these transactions in the next block or risk the block being invalidated if gas remains.

Once decryption material is released and attested by a two-thirds supermajority of attesters, the builder decrypts and places the transactions at the top of the block to prevent MEV abuse. If the decryption material isn’t sufficiently attested, the transactions are deferred to the next IL. The proposer includes the final block via ePBS, but failure to include valid IL transactions can result in slashing or rejection.

Ethereum faces a growing censorship problem that threatens its core principles of decentralization and neutrality. The Holy Trinity of Censorship Resistance, consisting of ePBS, FOCIL and encrypted mempools, presents a comprehensive solution that could restore Ethereum’s foundational values. As the network continues to evolve toward becoming a global settlement layer, implementing these measures will be crucial to ensuring that Ethereum remains true to the vision outlined in its whitepaper: a credibly neutral, decentralized platform accessible to all.