CoinDesk
Alice & Bob researchers estimate that a quantum computer with about 30,000 physical qubits could break the cryptography protecting Bitcoin wallets in roughly 62 minutes. Their estimate of 29,588 qubits is about 17 times lower than Google's earlier estimate of fewer than 500,000, though the studies use different hardware designs and assumptions.
Why it matters
At roughly 62 minutes, the modeled attack is too slow to reliably steal funds from a transaction before Bitcoin confirms it, typically after a 10-minute block interval. The more exposed risk is BTC held at addresses whose public keys are already visible: researchers say more than 6 million bitcoins sit behind such keys, giving a potential attacker more time to derive private keys.
The researchers stress that the scenario is theoretical. Alice & Bob expects hardware improvements and falling resource requirements to converge in the early 2030s. The model uses Shor's algorithm, which could let a sufficiently powerful quantum computer solve the mathematical problems underpinning current wallet cryptography.
Market impact
This is a security-planning signal, not evidence that Bitcoin wallets can be cracked with current machines. The findings increase pressure on Bitcoin developers to begin moving toward quantum-resistant security before capable hardware arrives.
Changing signature systems across a decentralized network could take years. That makes the timeline relevant now: developers must weigh a long migration against uncertain quantum progress, while the exposed-key holdings represent a distinct, longer-duration risk. Alice & Bob's researchers say further work is needed to determine whether adding qubits could reduce the modeled attack time below Bitcoin's block interval.
Frequently asked questions
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How many qubits does Alice & Bob estimate could break Bitcoin wallet cryptography?
The researchers estimate about 30,000 physical qubits, giving a specific estimate of 29,588. The finding is theoretical, and it differs from Google's earlier estimate.
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Why are exposed Bitcoin public keys a concern in the study?
Researchers say more than 6 million bitcoins are held at addresses with exposed public keys. Those funds could give an attacker more time to derive private keys than a pending transaction would.
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Could the modeled attack steal Bitcoin before a transaction is confirmed?
At roughly 62 minutes, the modeled attack is too slow to reliably target a transaction before Bitcoin's typical 10-minute confirmation interval.
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How does the estimate compare with Google's earlier quantum model?
Alice & Bob's estimate of 29,588 qubits is about 17 times lower than Google's earlier estimate of fewer than 500,000. The studies use different hardware designs and assumptions.
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Why do the researchers call for Bitcoin developers to act now?
Replacing vulnerable signatures across Bitcoin's decentralized network could take years. The researchers say preparation should begin before quantum hardware potentially advances toward threatening capabilities in the early 2030s.
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