Post-Quantum (PQ) Interop #28, February 25, 2026

Ethereum Magicians

Agenda Resources Facilitator email: will@ethereum.org Facilitator Telegram: @corcoranwill Telegram : PQ Interop — threads: #general , #devnet-1 , #devnet-2 , #devnet-3 , #tooling , #leanVM , #onboarding High-Level Documents Devnet-0 : lean consensus client interop Devnet-1 : PQ signature signing & verification Devnet-2 : single-layer PQ signature aggregation Devnet-3 : aggregator role separation + subnet aggregation A. Devnet-3: Implementation Status Client Readiness Client Implementation Spec Tests Interop Docker Notes Zeam Ready to interop, waiting for other clients. Working on checkpoint sync issues. leanQuickStart ready for Devnet-3. Ream Spec fully implemented. Self-finalization tests not passing yet (debugging). Docker image ready for testing imminently. Qlean Kamil traveling (AFK this call). Lantern All specs implemented, tests passing. Local 4-node test showed justification/finalization. Ready to release Devnet-3 image for interop. Ethlambda Internal 4-node Devnet running. Testing Devnet-3 implementation. Added checkpoint sync + chain guidance support. Next: code review/polish for Devnet-3 branch. Lighthouse Back after ~1 month. Starting to target Devnet-3. Will take more time. Grandine Multiple Devnet-2 fixes landed, more stable now. Still significant work remaining for Devnet-3. Nimbus No representative on call. Legend : Complete | In progress | Not started | Unknown Devnet-3 Interop Status Zeam + Lantern : Both ready to begin interop testing Ream : Docker image expected within days; debugging self-finalization Ethlambda : Internal testing in progress, polish phase next B. Devnet-4: Specification Status Recursive Aggregation API Complete (Emil) Finished : Recursive aggregation implementation ready API approach : Simplified — no Merkle tree of pubkeys needed When verifying aggregated signature, simply feed the list of public keys directly Most efficient approach after testing alternatives Link : Test with API shared in Telegram (leanVM channel) Next : Working on optimizations Spec Discussion: SSZ Signature Container Issue raised (Unnawut): leanSpec serializes signatures as variable-size lists (path/hashes), but all clients implement fixed-size bytes. Discussion : Lantern implemented variable-size per spec but added fixed-size fallback Fixed-size is cheaper and matches all client implementations Root cause: Variable-size was likely an early spec choice that doesn’t reflect the constant dimensions Resolution : Thomas to update spec to use fixed-size (vector instead of list). Unnawut reverting Ream back to fixed-size. Research Updates leanSpec minimal client (Thomas): Interop tests passing locally (self-interop). Sync still flaky, but networking and fork choice stable. Specification book (Thomas): Added 3SF-mini section, to be published soon. Pubkey PQ registry (Thomas): Starting to draft a post on post-quantum public key registry. Beacon spec modernization : Discussions ongoing about merging with leanSpec. C. Long-Running Devnet-2 & Checkpoint Sync Devnet-2 Stability 24+ hours finalized : Long-running Devnet-2 reached almost 24 hours of continuous finalization Ream : Reached 13,000 slots; fixed log size issues Grandine : Multiple stability fixes landed Checkpoint Sync Testing (Katya) Found working combination for 4 clients Testing order : Zeam → Ethlambda → Lantern Lantern implementing checkpoint sync flag for Devnet-2 image (serving finalized/justified states) Devnet-2 Bug Fixes Client Fix Lantern QUIC certificate rotation when expired Ethlambda Reduced memory during long syncs (upload pending blocks to disk); improved checkpoint sync; added chain guidance support; wrote checkpoint sync + consensus documentation D. New Client Onboarding Client Target Devnet Implementation Spec Tests Interop Docker Notes Gean Devnet-1 → 2 Integrated leanSig (block/attestation signing, signature verification). Integrated leanMetrics for Devnet-1. PR for leanQuickStart expected tomorrow for multi-client interop. Then targeting Devnet-2. Meeting Time: Wednesday, February 25, 2026 at 14:00 UTC (60 minutes) GitHub Issue 1 post - 1 participant Read full topic