Researchers at the quantum hardware company Alice & Bob calculate that a system featuring around 30,000 physical qubits could compromise the encryption securing bitcoin wallets in roughly sixty-two minutes, demanding significantly less hardware than past models indicated.
Back in March, Google estimated that an advanced quantum computer would require fewer than 500,000 physical qubits to crack Bitcoin cryptography, representing a major drop from earlier projections numbering in the millions. The fresh projection from Alice & Bob sits at 29,588 qubits, which is roughly 17 times lower than Google’s prior figure, though both investigations rely on distinct hardware configurations and foundational assumptions.
These discoveries imply that the processing power needed to pose a threat to Bitcoin might be lower than previously anticipated, potentially drawing such cyberattacks closer to reality than many thought.
The study by Alice & Bob also intensifies worries regarding bitcoin funds situated in addresses where public keys have already been revealed. A public key permits the Bitcoin network to validate transactions without disclosing the private key required to authorize expenditures. A potent quantum computer might theoretically reverse-engineer the public key to reconstruct that private key and misappropriate the funds.
“Yes, it becomes of utmost importance that migration starts now,” Dahmun Goudarzi, senior cryptanalyst at Alice & Bob told CoinDesk. “We know how hard and long this task can be, and this paper shows that Shor’s algorithm could be run sooner than later.”
Executing the attack would require approximately 62 minutes, contrasted against Bitcoin’s typical block duration of 10 minutes. This temporal gap renders the method too sluggish to reliably swipe assets from a transaction prior to its validation. When questioned about whether incorporating additional qubits might compress the duration beneath 10 minutes, Goudarzi noted that his group has not yet finalized the requisite math.
“There is no architectural floor,” stated Goudarzi, who holds a PhD in cryptography. He additionally mentioned that subsequent efforts might yield estimates matching Google’s preceding study, which simulated an assault requiring about nine minutes.
This distinction carries weight because bitcoin confronts two distinct categories of quantum exposure: transactions awaiting validation and BTC retained at addresses featuring revealed public keys. The latter scenario affords an adversary extended windows to compute a private key.
Exceeding 6 million bitcoins rest behind vulnerable, revealed public keys, rendering those holdings potential objectives for prospective quantum breaches.
Goudarzi emphasized that the conclusions reached by Alice & Bob remain entirely theoretical. He added that his organization anticipates technological enhancements and shrinking resource demands to align during the early 2030s.
Such dynamics place Bitcoin engineers before a challenging schedule: substituting vulnerable signature frameworks across a decentralized network could demand years, even while the machinery capable of exploiting them remains under construction.
The scientists at Alice & Bob utilized Shor’s algorithm, an approach capable of empowering sufficiently advanced quantum systems to resolve mathematical equations that standard computers fail to crack within a workable timeframe.
A qubit functions as the fundamental data unit within quantum machinery, capable of representing a 0 and a 1 simultaneously, thereby empowering it to resolve intricate problems far more rapidly than a traditional computer, where the fundamental data unit is a standard bit restricted strictly to either a 0 or a 1, but never both.
Originally published at https://www.coindesk.com/tech/2026/10/29/new-quantum-model-slashes-hardware-needed-to-break-bitcoin-keys-by-17-times.
