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

Governance Fund Missions 🏹
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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)