Post Quantum transaction signature #10

Protocol Calls & happenings
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Agenda

  • PQ MPC wallet (demo)
  • Post-quantum EVM multisig on a stock Safe

Meeting Time: Wednesday, June 10, 2026 at 13:00 UTC (60 minutes)

GitHub Issue

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Meeting Summary:

This was the tenth post-quantum transaction signature breakout room meeting focused on MPC and multisig implementations. Matteo Vena and Matteo Vicari from Riva Labs presented their ephemeral keys protocol, demonstrating multi-chain wallet functionality and post-quantum multisig capabilities that allow users to maintain stable identities across different Layer 2 networks while using hash-based signature schemes. Jay demonstrated a distributed key share wallet using MLDSA (a lattice-based signature scheme) with both cloud-hosted and hybrid authentication setups, showing how it can scale to 2-3 parties efficiently but would become impractical beyond 7-8 parties. The discussion included technical details about gas costs, security guarantees, and the challenges of implementing post-quantum signatures on Ethereum, with participants debating the merits of hash-based versus lattice-based approaches and the potential for formal verification of smart contract implementations.

Click to expand detailed summary

The meeting began with Antonio sharing his screen and checking if Gottfried could see his PDF and tools bar. Participants joined the call, including Matteo Vicari, Alessandro, Benedict, Matteo Vena, Conor, and Miha. Antonio waited for the scheduled presenter to join, expressing uncertainty about their arrival and mentioning the possibility of it being someone else.

Antonio welcomed participants to the tenth post-quantum transaction signature breakout room meeting focused on MPC and multisig topics. The agenda included presentations or demos from two teams: one on quantum-safe MPC using Dilithium version presented by Zigay Nox, and another from River Labs on post-quantum multisig solutions. Antonio noted that Science Lab was expected but had not yet joined the call, so he invited River Labs to begin their presentation.

Matteo Vena presented an update on Riva Labs’ ephemeral keys protocol, highlighting its key components including the rotation mechanism, force recover function, and multichain support. He demonstrated the protocol’s browser extension “NiceTry” which enables users to maintain a stable identity across different Layer 2 networks while remaining post-quantum secure. The team has also developed support for multi-device wallets and introduced multisig functionality through Safe, allowing users to incorporate post-quantum security into existing multisig setups.

Antonio and Matteo discussed plans to standardize their post-quantum signature protocol as an ERC (Ethereum Request for Comment) to establish it as an official Ethereum standard. The team is also exploring the possibility of implementing MPC (Multi-Party Computation) with hash-based signatures, though Benedikt noted this would be challenging due to the lack of algebraic structure in hash-based systems and potential impossibility results. The team plans to continue experimenting with different approaches and aims to have a working demo within a month, with the next call scheduled in two weeks.

Jay demonstrated a distributed key share wallet using MLDSA with two modes: cloud-hosted key share and a hybrid setup combining cloud and phone for two-factor authentication. The system can scale to 2-3 parties efficiently, with theoretical limits around 10 parties before performance degradation. The team is working on publishing two academic papers: one on the MLDSA-MPC algorithm and another on hash-based signature impossibility results, with the code being prepared for open source release.Reno and others discussed concerns about gas costs, with current implementations using SHAKE being expensive due to NIST compliance requirements, though alternatives using Keccak exist to reduce costs. The group debated the trade-offs between maintaining NIST compliance versus adopting industry-standard algorithms like MLDSA, with Reno expressing concerns about creating infrastructure that diverges from global standards.

Next Steps:

  • Matteo Vena: Draft an ERC based on the ephemeral keys protocol and share it with the breakout room group for community feedback and comments.
  • Antonio: Research the ERC submission procedure and requirements to help guide the process of turning the ephemeral keys protocol into an official Ethereum standard.
  • Antonio: Reach out to Matteo Vena and Riva Labs to collaborate as co-author on the ERC draft for the ephemeral keys protocol.
  • Matteo Vena: Continue development of the hash-based MPC design and aim to have a working demo ready within approximately one month to share with the group.
  • Jay: Share the ePrint link for the impossibility results paper on hash-based threshold signatures with the group.
  • Jay: Share the ePrint link for the MLDSA MPC protocol paper with the group once it is published.
  • Jay: Check with the team on the security model details (corruption threshold, guaranteed output delivery vs. security with abort) and follow up with Benedikt’s questions.
  • Jay: Open-source the MLDSA MPC code after the audit is completed.
  • Reno: Follow up with LFG Labs (developers of Verity) to explore formal verification of the Solidity MLDSA contract to confirm equivalence with the NIST specification.

Recording Access:

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YouTube recording available: https://youtu.be/yhOv9bpbqL8