Google Says Quantum Computers Could Break Crypto Sooner Than Expected

• Google says quantum tech could break ECDLP-256 with fewer resources, cutting hardware needs by 20x.
• Early warnings on ECC failure by the 2030s gain validation from Google’s new findings.
• Bitcoin’s governance slows upgrades, leaving a narrow window to counter quantum threats.

In a whitepaper published this week, researchers from Google Quantum AI stated plainly that most blockchain technologies and cryptocurrencies rely on elliptic curve cryptography, known as ECDLP-256, and that future quantum computers may break it with significantly fewer resources than previously understood.

Google’s team compiled quantum circuits capable of cracking ECDLP-256 using fewer than 1,200 logical qubits and 90 million Toffoli gates, executable on a machine with under 500,000 physical qubits in a matter of minutes. That represents a roughly 20-fold reduction in the hardware previously thought necessary.

“While viable solutions like post-quantum cryptography exist, they will take time to implement, bringing increasing urgency to act,” Google stated.

What makes Google’s whitepaper notable isn’t that it started the discussion, but that it validated a debate already active across research forums and crypto communities long before any formal warning.

Back in 2023, researcher Pierre-Luc was sounding alarms that few wanted to hear. “First keys will probably break in seven to ten years and cost a fortune,” he wrote at the time. “In the 2030s, ECC will become completely unusable.”

His warnings were met with the full spectrum of responses. Some pushed back hard. “There is no evidence of that,” one Bitcoin holder replied. “If it actually is a threat, Bitcoin can upgrade.” Pierre-Luc had a pointed response ready. “How do you upgrade the Satoshi wallets?” Nobody had a clean answer then. Nobody has one now.

The Sceptics Were Loud, and Some Remain Unconvinced

Throughout 2024, the sceptic camp held firm. One researcher publicly offered to bet half a Bitcoin that no quantum computer would break ECDLP-256 by 2029. When Elon Musk asked Grok in August 2025 to estimate the probability of quantum computing cracking SHA-256, the answer came back near zero within five years, a conclusion NIST and IBM broadly supported.

But analysts said the question itself was slightly off target. SHA-256 and ECDLP-256 are separate problems, and ECDLP-256 is the one protecting private keys. 

Daniel Batten made the distinction plainly at the time: “The right question is whether quantum computing can break ECDLP. That is still very hard, but easier to crack than SHA-256. If cracked, attackers can steal funds by deriving private keys from public keys.” That is precisely the scenario Google’s whitepaper now puts formal weight behind.

Now, Google has said that, “Our analysis gives the first clear indication that superconducting qubits could launch attacks within the average block time of Bitcoin and Bitcoin Cash, thus enabling “on-spend” attacks whereby a transaction is intercepted, the key is broken, and a fraudulent transaction is syndicated in the brief period of time before it is recorded on the blockchain.”

Developers Are Moving, But Slowly

Even before Google’s paper landed, Ethereum researchers were acknowledging the problem. Vitalik Buterin outlined plans for a post-quantum upgrade, though critics described the roadmap as still vague. “It’s time to start upgrading large accounts on Ethereum, ECDLP is one of the easiest task for the quantum computers being built by 2029,” Pierre-Luc wrote in May 2024. 

Bitcoin faces an even deeper challenge. Its governance model makes rapid protocol changes exceptionally difficult, and the gap between a quantum breakthrough becoming public and a network-wide upgrade being completed could be dangerously narrow.

Google is now collaborating with Coinbase, the Stanford Institute for Blockchain Research, and the Ethereum Foundation on responsible transition frameworks, working toward a 2029 migration timeline.

The Uncomfortable Truth

The answer to whether quantum computers can currently break Bitcoin or Ethereum is no. The answer to whether they eventually will, absent preventative action, is almost certainly yes.

The researchers who raised this years ago were not paranoid. They were early. Google just made that official.

Related: Google Sets Public 2029 Deadline for Post‑Quantum Cryptography