Quantum Threat to Bitcoin Shrinks: 30,000 Qubits Could Crack Keys in 62 Minutes
TREE NEWS reports: A new theoretical study from quantum computing firm Alice & Bob suggests that breaking Bitcoin’s 256-bit elliptic curve cryptography (ECDLP-256) may require only about 29,588 physical qubits and roughly 62 minutes of computation. That is approximately 17 times fewer qubits than Google’s March estimate of under 500,000, thanks to the company’s cat qubit architecture, which is designed to reduce error correction overhead.
Why the Numbers Matter
Bitcoin’s security relies on the computational difficulty of deriving a private key from a public key. A quantum computer running Shor’s algorithm could theoretically reverse that process. The new estimate lowers the hardware barrier significantly, but the 62-minute runtime remains longer than Bitcoin’s average 10-minute block time. That means an attacker still could not reliably hijack a transaction before it is confirmed.
However, the risk is not uniform. Addresses whose public keys are already exposed on-chain—such as reused addresses or those spent from—are more vulnerable. The study estimates that over 6 million BTC sit in such addresses, representing a substantial pool of value that could be targeted by a future quantum adversary.
Industry Implications
- Migration urgency: The findings add weight to calls for Bitcoin to adopt quantum-resistant signature schemes, such as those based on hash functions or lattice cryptography, before quantum hardware matures.
- Wallet hygiene: Users should avoid reusing addresses and move funds to fresh addresses to limit public key exposure.
- Protocol debate: Any post-quantum upgrade would require a soft or hard fork, raising complex governance and backward-compatibility questions for the Bitcoin community.
Forward Outlook
Alice & Bob expects hardware progress and declining resource requirements to intersect in the early 2030s, a timeline that leaves roughly five to seven years for the ecosystem to prepare. While the study is theoretical and assumes idealized error correction, it signals that the quantum threat is no longer a distant abstraction. Bitcoin developers, custodians, and institutional holders should begin evaluating migration paths and contingency plans now—before the gap between quantum capability and network defense narrows further.
