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Google warns five quantum attack paths could put $100 billion on Ethereum at risk

A 57-page whitepaper identifies how future quantum computers could target Ethereum's wallets, smart contracts, staking system, Layer 2 networks and data verification layer, with combined exposure exceeding $100 billion.

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Google warns five quantum attack paths could put $100 billion on Ethereum at risk

A 57-page whitepaper identifies how future quantum computers could target Ethereum’s wallets, smart contracts, staking system, Layer 2 networks and data verification layer, with combined exposure exceeding $100 billion.

By Shaurya Malwa|Edited by Stephen Alpher

Updated Mar 31, 2026, 12:11 p.m. Published Mar 31, 2026, 12:02 p.m.

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What to know:

• A new Google Quantum AI paper warns that quantum computers could exploit at least five vulnerabilities in Ethereum, putting more than $100 billion in assets at risk.
• Because Ethereum public keys become permanently visible once a user transacts, Google estimates the top 1,000 wallets and at least 70 major admin-controlled smart contracts, including those backing key stablecoins, are exposed to quantum attacks.
• The paper finds that Ethereum’s proof-of-stake system, major Layer 2 networks and a one-time data availability setup are all vulnerable, and while the Ethereum Foundation is pursuing quantum-resistant upgrades by 2029, existing contracts and infrastructure must each be upgraded and rekeyed independently.

Most of the online reaction to Google Quantum AI’s paper, released late Monday, focused on bitcoin. The nine-minute attack, a 41% theft probability and the 6.9 million in possibly exposed BTC.

Ethereum’s section got less attention. It deserves more.

The whitepaper, co-authored with Ethereum Foundation researcher Justin Drake and Stanford’s Dan Boneh, mapped five ways a quantum computer could attack Ethereum, each targeting a different part of the network.

The combined exposure exceeds $100 billion at current prices, and the knock-on effects could be far larger.

Wallets that can never hide

On bitcoin, your public key (the cryptographic identity tied to your funds) can stay hidden behind a hash, a kind of digital fingerprint, until you spend. On Ethereum, the moment a user sends a transaction, their public key is permanently visible on the blockchain.

There is no way to rotate it without abandoning the account entirely. Google estimates the top 1,000 Ethereum wallets by balance, holding roughly 20.5 million ETH, are exposed.

A quantum computer cracking one key every nine minutes could work through all 1,000 in under nine days.

The master keys to DeFi

Many smart contracts on Ethereum, the self-executing programs that power lending, trading and stablecoin issuance, give special privileges to a handful of administrator accounts. These admins can pause the contract, upgrade its code, or move funds.

Google found at least 70 major contracts with admin keys exposed on-chain, holding about 2.5 million ETH. But the bigger risk is what those keys control beyond ETH.

Admin accounts also govern minting authority for stablecoins like USDT and USDC, meaning a quantum attacker who cracks one could print unlimited tokens. The paper estimates roughly $200 billion in stablecoins and tokenized assets on Ethereum depend on these vulnerable admin keys.

Forging even one could trigger a chain reaction across every lending market that accepts those tokens as collateral.

Layer 2s built on vulnerable math

Ethereum processes the bulk of its transactions through Layer 2 networks, separate systems like Arbitrum and Optimism that handle activity off the main chain and report back.