Banks aiming to be ready for Ethereum’s planned quantum-resistant Layer 1 transition should begin overhauling their custody systems by 2027, according to Thomas Brunner, head of custody and staking at Sygnum Bank. Ethereum developers are weighing a tentative timeline that could see the network shift to post-quantum cryptography by 2029.
Brunner warned that adopting quantum-resistant signatures is not a routine software update. New cryptographic methods may prohibit key reuse, which conflicts with standard banking practices such as system duplication, rollbacks, and disaster recovery. Identifying cryptographic keys and dependent systems alone could take six months to a year, followed by hardware support, certification, internal reviews, external audits, and regulatory approvals.
The warning coincides with rising venture interest in quantum-ready infrastructure. Moon Pursuit Capital founder Utkarsh Ahuja said investors will prioritize post-quantum security and blockchain migration tools heading into 2027. Global VC investment reached $227.4 billion across 8,440 deals in Q2 2026, according to KPMG, though much of that flowed to large AI companies. Moon Pursuit co-led AmericanFortress’ $8 million seed round with SAVA Digital Asset Fund and 0G Labs. AmericanFortress has proposed a quantum-resistant wallet scheme known as ZK-PoSP, covering addresses on Bitcoin, Ethereum, and Solana without requiring holders to move funds or rotate keys.
NIST finalized its first three post-quantum cryptography standards in August 2024 and has called for vulnerable algorithms to be deprecated by 2030. Ethereum Foundation researcher Justin Drake said on Aug. 13 that Ethereum’s future layer-1 design will move away from the Poseidon hash function and adopt established functions such as SHA-2 or BLAKE2s. A production version of leanVM is scheduled for 2027, followed by planned protocol deployments in 2028. BitGo and Silence Laboratories also completed a post-quantum signing test in May using the ML-DSA algorithm.
Ahuja said crypto investors must think further ahead than they traditionally have, because upgrading blockchains, wallets, and user infrastructure could take years. Moon Pursuit will assess companies based on how easily their products can adapt when cryptographic requirements change, and how well they can move users and assets without major disruption.
