The permissionless fault proof system is launched on the OP mainnet. Here is a quick look at its features

Author: The Optimism Collective & Op Labs; Translation: 0xjs@黄金财经

On June 10, 2024, the governance-approved, permissionless fault proof was launched on the OP mainnet, and the OP Stack entered Stage 1. This is an important milestone for the super chain, and soon more OP Stack chains will be upgraded to include this feature, starting with Base, Metal, Mode, and Zora.

The permissionless fault proof system allows ETH and ERC-20 tokens to be withdrawn from the OP mainnet without the involvement of any trusted third party. This also means that any user who wants to participate in the protocol can challenge and delete invalid withdrawals. While participation in the fault proof system is permissionless, the Optimism Security Committee reserves the right to intervene and restore the system to a permissioned state in the event of a system failure. Having this backup is part of a responsible and secure rollout of the fault proof system, and the Optimism Security Committee meets L2Beat's well-established industry standard definition of Phase 1.

A Quick Look at the Fault Proof System

The fully functional Fault Proof System enhances the security of bridged ETH and ERC-20 tokens, and its functionality paves the way for full decentralization.

Improved Trust Model

The permissionless Fault Proof System enables users to withdraw ETH and ERC-20 tokens from L2 to L1 without involving any trusted third party like a sorter or any other centralized infrastructure.

This means that withdrawals no longer rely on the privileged proposer role to publish output roots. Instead, anyone can now publish output proposals through the Fault Dispute System. Output proposals make a claim about the state of L2. Once finalized, the claim can be used to facilitate withdrawals without taking any privileged action. Even if the Security Council revokes withdrawals.

Anyone Can Contribute to Security

Any user who wants to participate in the protocol can challenge and remove invalid proposals.  

The dispute game provides a mechanism to determine the validity of an output proposal. Anyone can dispute the validity of an output proposal by participating in its associated dispute game. Each action requires the placement of an ETH bond, with dishonest bonds paying honest bond holders to cover gas costs.

Security Council as a Safety Net

As outlined by Vitalik Buterin in his Rollup Decentralization Vision, there can be temporary training wheels, a safety mechanism that can override the Fault Proof System in an emergency. This led to the introduction of a permissionless Fault Proof System, with the Optimism Collective’s Security Council as a fallback. At a 75% signature threshold, it can intervene in the event of a Fault Proof System failure or manual upgrade.

This system reduces trust assumptions, paving the way for full decentralization. The OP Labs team’s roadmap aims to achieve a second phase of decentralization for the OP Stack, with the training wheels removed when the technology is proven to be secure.

Modular design for multiple protections 

The modular nature of the fault proof system enables the integration of additional proof mechanisms, laying a solid foundation for future multi-proof systems. Thanks to the smart contract framework included in this upgrade, additional proof systems can be easily added.  

Working together, these proofs will provide an enhanced layer of security during production. As OP Stack moves towards achieving Phase 2 decentralization, this will further reduce trust assumptions in subsequent upgrades.

However, OP Stack did not reach Phase 1 by implementing fault proofs alone. Additional protections specifically for the system ensure that the Security Committee can act quickly and effectively when errors occur. If a protection measure is triggered, withdrawals will be reset, so all pending withdrawals will need to be re-proven. Security is the top priority for everything built into OP Stack, and these efforts, combined with the fault proof work, have brought OP Stack to Phase 1 functionality.

Next Stop: Stage 2

In 2022, Vitalik outlined a framework for how L2s can gradually shed their training wheels and move toward full decentralization. L2 projects typically start early in the stages of development and launch the ecosystem before the security model is fully permissionless. As projects progress, they can shed their training wheels and advance from Stage 0 to Stage 1 and eventually to Stage 2 decentralization.

Now that OP is confident in the security model of Stage 1, and the core development team and some of the most respected and diligent security auditors in the ecosystem have thoroughly vetted the Security Council’s ability to keep the system secure under any circumstances, the next step is to work toward Stage 2. Next up: an audit of the Dispute Game itself, which will take place in July.

But looking ahead, it’s imperative to look beyond Stage 1.

L2s are in various stages of development, and these projects typically build the ecosystem and harden the code at the same time. As the project matures, its code will continue to improve and the decentralization process will continue to advance. Earlier security measures or “auxiliary tools” are no longer necessary.

Launching Fault Proofs on the OP Mainnet, expanding functionality to other OP Stack chains in the Hyperchain ecosystem, and achieving Phase 1 decentralization are important milestones. But the endgame is Phase 2 decentralization.

The current Fault Proof system lays the foundation for achieving “Multi-Proof Nirvana” - like OP Stack itself, it is open source and modular by design. The framework is designed to enable OP Stack to support multiple proof systems, including zero-knowledge proofs as well as the current system Cannon. Putting redundant proof schemes into production to ensure withdrawals from OP Stack Chains back to Ethereum can limit the role of the Security Committee to only choosing between proofs in the event of disagreement.

The Proof-of-Fault system was built and tested by core development teams from Superchain such as OP Labs, Base, and Sunnyside Labs. This collaborative approach made this launch possible. The Proof-of-Fault proposal was also approved by Optimism’s Token House and Citizens’ House, passing the two-step approval process of Optimism governance.

In the coming months, we seek to launch other proof systems on testnets, including Asterisc and Kona. Demonstrating the reliability and robustness of these redundant proof schemes will help Superchain achieve phase 2 decentralization.

We are celebrating the launch of Proof-of-Fault, and the entry of OP Stack into phase 1, and are optimistic about Superchain’s path to a fully decentralized future.