Quantum Computing Could Crack Top 1,000 ETH Wallets in Days

A quantum attacker could potentially steal funds from a transaction while it is still waiting to be processed.

Google’s quantum computing team has published a white paper detailing how a sufficiently advanced quantum computer could crack the private keys of Ethereum’s 1,000 wealthiest wallets in under 9 days, directly risking more than 20 million ETH.

In addition, the paper introduced a timeline that researchers say no longer allows room for complacency.

What Google’s Research Found

To understand the risk, it helps to know how crypto wallets stay secure today. Every wallet has a private key, a secret password of sorts, and a public address that others can see. The security system currently used by Ethereum makes it essentially impossible to work backwards from the public address to the private key. Quantum computers, once powerful enough, would break that barrier entirely.

According to the Google paper, Ethereum is vulnerable at five separate levels. The most direct threat is to individual wallets: the top 1,000 alone hold around 20.5 million ETH. But smart contracts, the self-executing programs that power most of Ethereum’s financial activity, are also at risk. Their administrator keys control roughly $200 billion in stablecoins and other real-world assets.

Beyond that, validators who keep Ethereum’s network running hold 37 million ETH in staked funds, and the systems that support Ethereum’s layer-2 networks each carry exposure worth around 15 million ETH.

The danger is not just theoretical, with Google estimating that a fast quantum computer could crack a single wallet’s private key in about nine minutes. Putting that in the context of Bitcoin would show just how grave the situation might be, especially if you recall that a new Bitcoin block is confirmed about every ten minutes. It means that a quantum attacker could potentially steal funds from a transaction that is waiting to be processed before it even clears. Crypto research group Project Eleven described this as a “mempool attack,” something the crypto community had previously assumed was far off.

The Warning May Come Too Late

Google’s paper puts the qubit requirements for this attack at either 1,200 logical qubits and 90 million computational operations or 1,450 logical qubits and 70 million operations, depending on the architecture. According to Project Eleven, this is a 10x improvement over previously published estimates.

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Interestingly, on the same day Google released its findings, researchers from Oratomi, Caltech, and UC Berkeley published separate work showing that Shor’s algorithm could run at cryptographically relevant scales with as few as 10,000 reconfigurable atomic cubits, with ECC-256 potentially falling in five days on a 22,000-qubit machine.

Nonetheless, opinion is divided on how close the threat actually is. Some analysts have argued that the danger is at least a decade away and that it will first hit the broader internet infrastructure, giving markets time to respond. But others are already setting things in motion, with Google, for example, setting a 2029 deadline to upgrade its own systems, and Ethereum co-founder Vitalik Buterin recently published a quantum resistance roadmap for the network, laying out how its security systems could be replaced with ones that quantum computers cannot break.