A new paper co-authored by Google Quantum AI, Ethereum Foundation researcher Justin Drake, and Stanford cryptographer Dan Boneh argues that Ethereum faces five major quantum attack paths. The paper says the directly exposed assets already exceed $100 billion at current prices, while stablecoins and tokenized assets that depend on vulnerable admin keys amount to roughly $200 billion.
Whale wallets could be exposed once public keys appear on-chain
The paper draws a sharp distinction between Bitcoin and Ethereum account exposure. In Bitcoin, a public key can remain hidden behind a hash until funds are spent. On Ethereum, once an account sends a transaction, the public key is permanently visible on-chain. That leaves few options beyond abandoning the account and moving assets. Google’s team estimates that the top 1,000 Ethereum whale wallets, holding about 20.5 million ETH in total, are already exposed. If a future quantum computer could break a private key in 9 minutes, those wallets could be drained in less than 9 days.
Admin keys in DeFi and stablecoin systems are another weak point
The second path centers on administrator privileges inside smart contracts that support lending, trading, and stablecoin issuance. These privileged keys can often pause contracts, upgrade code, or move funds. According to the paper, at least 70 major contracts have admin keys already exposed on-chain, covering about 2.5 million ETH. The concern reaches beyond ETH itself. Some of those admin accounts also control minting powers tied to major stablecoins, which means a successful key compromise could affect issuance and the collateral structures built around those tokens.
Layer 2 networks, bridges, and staking all rely on vulnerable cryptography
The report says most Ethereum scaling networks, including Arbitrum and Optimism, rely on Ethereum’s built-in cryptographic tools, and those tools are not quantum resistant. It estimates that at least 15 million ETH across major Layer 2 systems and cross-chain bridges is exposed. The paper identifies StarkNet as the only option currently viewed as safer in this context because it uses hash-based cryptography rather than elliptic-curve signatures.
Quantum risk also reaches Ethereum’s Proof-of-Stake system. About 37 million ETH is currently staked on the network. The paper says an attacker controlling one-third of validator nodes could halt the chain, while control of two-thirds could allow direct manipulation of blockchain history. It also warns that concentration in staking pools matters. Lido, with roughly 20% market share, is cited as an example where attacking a single large operator’s infrastructure could shorten the path to disruption.
A one-time break could create a lasting data-verification exploit
The fifth attack path focuses on Ethereum’s data availability sampling design. The paper says the setup process originally generated a secret value that was supposed to be destroyed. A quantum attacker, it argues, could reconstruct that value from public data. The danger is persistence: once recovered, the secret could keep being used to forge data availability proofs without requiring a quantum computer each time. The authors describe such an exploit as highly valuable, and say any black-market spread would threaten Layer 2 networks that depend on Ethereum’s blob data system.
Ethereum has a post-quantum roadmap, but deployed contracts remain a hard problem
Drake said the Ethereum Foundation launched a post-quantum research portal last week. He added that this line of work has been underway for more than 8 years, with testnet efforts progressing weekly and a multi-stage hard fork roadmap aimed at full post-quantum cryptography by 2029. The paper also notes that Ethereum’s 12-second block time, compared with Bitcoin’s roughly 10-minute interval, raises the difficulty of real-time transaction interception.
Even so, a mainnet upgrade would not automatically protect the contracts already deployed on-chain. The paper says DeFi protocols, bridges, and Layer 2 networks would each need to update code and rotate keys on their own. In a decentralized system, no central authority can force every project to upgrade at the same time.