Google: 1,200 qubits could break Ethereum; Foundation plans 2029

A Google Quantum AI paper published in March 2026 reduced the estimated quantum hardware needed to break Ethereum account security from tens of thousands of logical qubits to roughly 1,200. The company set an internal 2029 deadline for migrating its own systems following the revision.

Ethereum uses the ECDSA signature scheme to verify transactions. When an account sends a transaction, its public key becomes visible on the blockchain. A sufficiently powerful quantum computer could use that public key to derive the private key and move funds from the account. Current quantum machines cannot perform that attack, but about 0.1% of Ethereum’s dormant funds are in accounts that have exposed public keys and are therefore technically vulnerable now. Other elements that rely on similar mathematics include validator signatures, data availability commitments and zero-knowledge proof systems used by many rollups.

The Ethereum Foundation formed a Post‑Quantum Security team in January 2026, with Thomas Coratger leading the effort. The foundation has published its work at pq.ethereum.org and added post‑quantum risk to its research planning. The foundation launched the Poseidon Prize, a $1 million award aimed at improving hash‑based cryptographic primitives.

Near-term protocol options under consideration include EIP‑8141, which introduces native account abstraction and would allow accounts to select post‑quantum signature schemes. EIP‑8141 is being evaluated for the Hegotá hard fork tentatively scheduled for the second half of 2026. The foundation has set a target of full protocol readiness around 2029, aligning with Google’s internal migration timeline.

For users and developers who do not want to wait for protocol changes, the foundation’s Kohaku project provides a way to deploy a quantum-resistant smart account on testnet using the ERC‑4337 account abstraction standard. The project lead, known as Nico, said the approach can be used now and does not require a hard fork; deployment on Layer 1 testnet costs about $0.07 in fees.

NIST finalized three post‑quantum cryptography standards in August 2024, which the foundation is using as building blocks for migration strategies. Other major blockchains that rely on ECDSA, including Bitcoin and Solana, have not announced dedicated post‑quantum teams or comparable migration roadmaps. The 1,200‑qubit estimate is not a certainty: quantum error correction and scaling remain active research challenges before hardware can reach the required capability.