[CLOSED] Governance Fund Mission Request: Cross-Chain Key Management for Safe

Grants đź”´ Governance Fund Missions
1

Season 8 Intent: A set of interoperable Stage 1 chains doing $100m per month in cross-chain asset transfer

Total grant amount: Up to 126,000 OP (funding 63,000 OP per team, up to 2 teams)

Should this Governance Fund Mission be fulfilled by one or multiple teams: Up to 2

OP Labs or Optimism Unlimited Sponsor: Pierce

Reviewing Body: Developer Advisory Board Foundation Mission Team

Submit by: October 31, 2025

Selection by: November 7, 2025

Start date: November 14, 2025

Governance Fund Mission Request

Cross-Chain Key Management for Safe

Consider this scenario:

  • An EOA is a signer on a Safe multisig deployed across multiple chains.
  • To update the signer to another address, signers have to propose, verify and sign tx on all these chains.

This ops heavy task leads to increased costs, time delays, and potential security risks from inconsistent states.

We invite proposals for building a Safe module which enables unified key management across the Superchain ecosystem.

Here is a high-level architecture of this Safe module based system:

This module can be assigned as a signer for Safe multisigs deployed across Superchain. This module, in turn, is owned by the address of the end user (an EOA for example).

To replace its address with another, the user updates the owner of the Safe module, which then communicates this change to modules deployed on other chains in Superchain. These modules then update their owner, effectively updating the signer on all the multisigs, thus removing the need for action from the user.

Proposing teams are free to choose other architectures if they can demonstrate clear advantages.

How will this Mission help accomplish this Season’s Intent?

Cross-chain key management remains a challenge. As the Superchain ecosystem grows, cross-chain key management becomes more and more complex as the user has to take action on multiple chains.

With Safe being the popular choice for multisig contracts, reducing the maintenance cost to operate them should positively impact cross-chain asset transfers as users are more likely to deploy Safe multisigs on different chains.

This system can be updated to use interop when it ships.

What is required to execute this Mission?

Technical Requirements:

  • Development of a Safe module smart contract that can be deployed across all Superchain networks
  • Implementation of cross-chain messaging infrastructure
  • Creation of a root/hub module that manages ownership state and propagates changes to child modules

Deliverables:

  • Open-source smart contracts with comprehensive documentation
  • Tests and deployment scripts
  • Integration guide for existing Safe deployments

How should progress towards completion be measured?

  • Milestone 1:
    • Completion of module architecture design and specification
    • Successful deployment of prototype on testnet across at least 3 Superchain chains
  • Milestone 2:
    • Successful ownership update propagation across 5 Superchain chains within 5 minutes
  • Milestone 3:
    • Apply for audit grant. If audit received, address audit feedback.

Application Instructions

To apply for this Governance Fund Mission, please complete the form in the expandable section below and leave your response as a comment on this forum thread. Submissions will be open until Oct. 10th, at which time the Developer Advisory Board will review all submissions and select up to 2 individuals/teams to complete the work defined here.

Submission Form

Submission Form

Copy the entire application below and leave a comment on this issue with your answers completed. A representative from the Developer Advisory Board may reach out using the contact info provided to request more information as necessary.

Governance Fund Mission Application

Please verify that your team members below:

  • Team Lead: Please specify the best point of contact for your team
  • Contact info:
  • L2 recipient address:
  • Please list the members of your team and link to any previous work:

What makes your team best-suited to execute this Mission?

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Please describe your proposed solution based on the above:

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Please outline your step-by-step plan to execute this Mission, including expected deadlines to complete each piece of work:

  • […]
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Please define the critical milestone(s) that should be used to determine whether you’ve executed on this proposal:

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Please list any additional support your team would require to execute this mission:

  • […]
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Please check the following to make sure you understand the terms of the Optimism Foundation Mission program:

  • I understand my grant for completing this Governance Fund Mission will be locked for one year from the date funds are transferred to the locked multisig wallet.
  • I understand that I will be required to provide additional KYC information to the Optimism Foundation to receive this grant
  • I understand my locked grant may be clawed back for failure to execute on critical milestones, as outlined in the Collective Grant Policies
  • I confirm that I have read and understand the Collective Grant Policies
6 Likes
Optimism Gov Summary
Season 9 Governance Fund Missions
2

Given the modest bounty on this, we would recommend relaxing this requirement, or at least directing them to the governance-subsidized audit program. Or raise the payout.

Otherwise, someone would have had to already have built this, in which case why offer a bounty. $14,000 of OP won’t cover significant expenses if someone doesn’t already have an off-the-shelf solution.

2 Likes
3

Agreed! We actually rephrased Milestone 3 to be “Apply for audit grant. If audit received, address audit feedback” which I think is much more reasonable for the budget. What do you think?

Will need to update the technical requirements point, too.

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4

@GFXlabs thanks for the feedback! We have removed it as a “Technical Requirement” to avoid confusion about who pays for the audit. Milestone 3 makes it clear they are expected to apply for audit grant.

5

Glad to see the audit requirement clarified. From a user perspective, cutting down the overhead of signer management is a huge win. saves gas, time, and lowers the chance of mistakes across chains.

6

UPDATE: We have revised the dates and increased the grant amount from 21K OP per team to 63K OP per team.

3 Likes
8

At WakeUp Labs, we are submitting our technical proposal for the Cross-Chain Key Management for Safe Mission, aligned with Optimism’s Superchain interop goals.

Please verify that your team members below:

What makes your team best-suited to execute this Mission?

  • WakeUp Labs is an established contributor within the Optimism ecosystem, having successfully completed previous Governance Fund Missions and RetroPGF-funded projects focused on interoperability, automation, and public goods.
  • The team has deep experience developing Safe-based modules and interop infrastructure, including fully on-chain reward automation for Velora DAO using UMA’s oSnap module and cross-chain health monitoring for OP Stack environments.
  • We combine technical expertise (smart contracts, SDKs, interop systems) with strong alignment to Optimism’s Impact = Profit values, ensuring the outcome will be open-source, reproducible, and beneficial to the entire Superchain.

Please describe your proposed solution based on the above:

We propose building a Cross-Chain Key Management Module for Safe, designed to enable unified signer management across the Optimism Superchain (Optimism, Base, Mode, Zora, and other OP Stack chains).

Goal

When a Safe owner rotates a signer (for example, replacing an EOA), the change will automatically propagate across all connected Safes, eliminating manual per-chain updates, preventing inconsistent signer states, and improving both usability and security.

High-Level Architecture

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Components and Roles

Component Role
RootModule (Hub) Deployed on a canonical chain (e.g., OP Mainnet). Acts as the authoritative registry of current Safe signers and initiates updates.
ChildModule (Spoke) Deployed on each Superchain chain. Receives and applies signer updates from the RootModule via Safe’s execTransactionFromModule.
Cross-Chain Messenger Handles secure message delivery between RootModule and ChildModules. Initially uses Optimism’s L2CrossDomainMessenger, later adaptable to the upcoming OP Interop protocol or external messaging layers like LayerZero.
Safe Multisig Integrates the ChildModule as a trusted module. Signer updates are executed through Safe’s standard module interface.

Update Flow

  1. The Safe owner or Root Safe calls one of the module’s functions:
    addSigner(address signer) – add new signer
    revokeSigner(address signer) – remove signer
    rotateSigner(address oldSigner, address newSigner) – replace signer
  2. The RootModule serializes and dispatches the update to all registered ChildModules through the cross-chain messenger.
  3. Each ChildModule verifies message authenticity and executes the corresponding Safe transaction:
  • addOwner(signer)
  • removeOwner(signer)
  • swapOwner(oldSigner, newSigner)
  1. Each Safe updates its local signer list, maintaining consistency with the RootModule state across the entire Superchain.
  2. Protection mechanisms include:
  • Nonce tracking to prevent replay attacks.
  • Verification that all messages originate from the legitimate RootModule.
  • Optional recovery function syncFromRoot() to handle delayed or failed messages.

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Please outline your step-by-step plan to execute this Mission, including expected deadlines to complete each piece of work:

Total Estimated Duration: 9 weeks

Milestone 1 – Research & Planning (2 weeks)

Objectives

  • Finalize architecture and module specification for cross-chain signer management.
  • Produce design diagrams, security model, and Root ↔ Child state-sync logic.
  • Validate cross-chain communication feasibility between OP Mainnet and one Superchain chain.

Deliverables

  • Architecture and specification document.
  • PoC demonstrating Safe transaction execution without manual signer approval.
  • PoC for message send/receive between OP Mainnet and another OP chain (e.g., Base or Mode).

Acceptance Criteria

  • Successful cross-chain message transmission and log verification between two Superchain testnets.
  • Completed technical report covering Root, Child, and Messenger components.

Milestone 2 – Core Development (3 weeks)

Objectives

  • Implement RootModule and supporting contracts.
  • Enable full signer rotation propagation across multiple chains.
  • Develop unit tests and deployment scripts.

Deliverables

  • Solidity contracts for RootModule and ChildModule.
  • Cross-chain propagation functional on more than two Superchain testnets.
  • Registration scripts for Safe integration.

Acceptance Criteria

  • Ownership rotation executed on RootModule propagates to five chains in under five minutes.
  • All core logic and event flows covered by automated tests.
  • Live demo.

Milestone 3 – QA & Reliability (3 weeks)

Objectives

  • Reinforce reliability and state synchronization across networks.
  • Implement recovery and re-sync for failed or delayed message deliveries.
  • Develop monitoring and validation tools for signer consistency.

Deliverables

  • Recovery function syncFromRoot() for manual state repair.
  • QA report verifying propagation and synchronization integrity.

Acceptance Criteria

  • Demonstrated recovery of a failed rotation via syncFromRoot().
  • Consistency validated across all tested chains.

Milestone 4 – Audit & Finalization (1 week)

Objectives

  • Apply to Optimism’s subsidized audit program.
  • Address and document any feedback received.
  • Prepare audit-ready documentation.

Deliverables

  • Updated and audited contracts.
  • Final documentation, SDK integration guide, and public report.

Acceptance Criteria

  • Audit request submitted and feedback incorporated.
  • Finalized public release repository (open-source under MIT license).

Please define the critical milestone(s) that should be used to determine whether you’ve executed on this proposal:

  • Milestone 1: Successful cross-chain message delivery between OP Mainnet and one Superchain chain (Base or Mode).
  • Milestone 2: RootModule signer rotation propagates to five chains in under five minutes with full test coverage.
  • Milestone 3: Verified recovery and synchronization mechanism operational.
  • Milestone 4: Audit request submitted and all feedback implemented.

Please list any additional support your team would require to execute this mission:

  • Access to OP Labs documentation and engineering guidance regarding OP Interop protocol (when available).
  • Subsidized audit through the Optimism audit grant program.
  • Optional technical alignment review with Safe Global’s engineering team.

Acknowledgements

:check_box_with_check: I understand my grant for completing this Governance Fund Mission will be locked for one year from the date funds are transferred to the locked multisig wallet.

:check_box_with_check: I understand that I will be required to provide additional KYC information to the Optimism Foundation to receive this grant.

:check_box_with_check: I understand my locked grant may be clawed back for failure to execute on critical milestones, as outlined in the Collective Grant Policies → Collective Grant Policies

:check_box_with_check: I confirm that I have read and understand the Collective Grant Policies → Collective Grant Policies

Submitted on behalf of WakeUp Labs (contact: optimism@wakeuplabs.io)

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9

Thank you for your applications and interest in this Mission.

The DAB has decided to move forward with the proposal made by:

We encourage everyone to keep an eye on this forum for future Mission Requests.

1 Like
11

Hi there, thank you for the submission but the mission is closed now, we just forgot to update the title. My apologies! @blockdev can you please update the thread title?

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12

marked application as closed.

13

Hey @WakeUp_Labs , I’ve reached out in DMs here. Please send your telegram handle there so that we can begin a group chat.

1 Like
14

Hi @blockdev, we replied to your DM. Thanks!

1 Like