Even as the world is focusing on the developments made in AI, there is another field of computing which seems to be producing some just as impressive — but more obscure — results.
Google’s Quantum AI division has published a whitepaper revealing that future quantum computers may be able to crack the encryption underpinning most major cryptocurrencies with significantly fewer resources than the security community had previously estimated — roughly 20 times fewer physical qubits than prior projections.
What The Paper Says
Most blockchain technologies — including Bitcoin and Ethereum — rely on 256-bit elliptic curve cryptography (ECC) to secure wallets and transactions. Google’s researchers have compiled two quantum circuits implementing Shor’s algorithm capable of breaking this encryption: one using under 1,200 logical qubits and 90 million Toffoli gates, and another using under 1,450 logical qubits and 70 million Toffoli gates. They estimate these could run on a superconducting quantum computer with fewer than 500,000 physical qubits in just a few minutes.
To put that in context: Google CEO Sundar Pichai has said that practically useful quantum computers are five to ten years away — and Google has already been making substantial hardware progress, including its Willow chip. The gap between “theoretically possible” and “imminent threat” is narrowing faster than anticipated.
A Responsible Disclosure Problem
The disclosure of quantum cryptanalysis research presents a unique challenge. Publishing detailed attack methods could fuel panic and undermine confidence in cryptocurrency markets — which, unlike traditional systems, derive value partly from public trust. But staying silent leaves billions of dollars in digital assets potentially exposed.
Google’s solution: a zero-knowledge proof. The researchers published a cryptographic construction that allows third parties to independently verify their resource estimates without Google releasing the actual quantum circuits that could serve as an attack blueprint. It’s a novel approach to a genuinely difficult disclosure dilemma, and one they’re urging other research teams to adopt.
The paper also engaged the U.S. government ahead of publication and has been developed in coordination with Coinbase, the Stanford Institute for Blockchain Research, and the Ethereum Foundation.
What Needs To Happen Now
Google is clear that the fix exists: post-quantum cryptography (PQC), a family of algorithms designed to resist quantum attacks. The challenge is that migrating major blockchains to PQC is a significant undertaking that will require broad industry coordination and time — neither of which is in great supply.
In the interim, Google recommends that users and platforms stop exposing or reusing wallet addresses that rely on vulnerable cryptographic schemes — a relatively simple step that reduces attack surface while longer-term solutions are built out.
Google has set a 2029 migration timeline as the benchmark for when these changes should be in place.
The Bigger Picture
Quantum computing is advancing on multiple fronts simultaneously — Google with its superconducting qubit processors, Microsoft with its topological qubit approach. The race to build cryptographically relevant quantum computers is real, and the financial infrastructure of the digital economy is not yet ready for it.
This paper is less a doomsday warning than a calibration — telling the industry precisely how far away the threat is, what it looks like, and what to do about it. The clock is ticking, but it’s not yet midnight.