A quantum computer could crack Bitcoin’s security in 26 days

A quantum computer could crack Bitcoin’s cryptographic security in just 26 days—and this is no longer just a theoretical threat. The American company IonQ has published the world’s first fully compiled, end-to-end attack plan against the 256-bit elliptic curve cipher that underpins the world’s largest cryptocurrency.

According to the researchers' calculations, a fault-tolerant quantum computer would be able to break the secp256k1 algorithm—the very one used by Bitcoin—in approximately 25.7 days. This would require a machine with 19,397 physical qubits. That’s less than 20,000—the milestone IonQ publicly highlighted in its announcement.

An important caveat: there has not yet been a real-world attack on Bitcoin. IonQ has not demonstrated a break on a live quantum computer. Instead, the researchers created a detailed engineering blueprint—specifying every operation the future machine would need to perform. Among the parameters are 1,457 logical qubits and approximately 39 million Toffoli gates.

Shor’s theoretical algorithm has long pointed to the vulnerability of public-key cryptography to quantum computing. But translating mathematics into actual hardware architecture is a fundamentally more difficult task. IonQ simulated the attack as a specific workload on a fault-tolerant system and utilized its own Walking Cat architecture, which combines trapped ions with quantum error correction methods.

John Gamble, IonQ’s vice president of architecture, emphasized that the result is an engineering blueprint, not an abstract theoretical assessment. The difference is significant: previously, such calculations often «cut out» parts of the system that actually dominate the execution time. Chris Bellance, President of Quantum Computing, noted that the researchers were able to calculate the lower bound on the probability of a successful attack.

IonQ’s roadmap calls for a fault-tolerant system with 10,000 physical qubits by 2027, with further hardware and manufacturing improvements expected around 2028. Progress across the entire stack—algorithm, compiler, architecture, and error correction—has made it possible to reduce the required resources to a scale that the company already plans to achieve in the coming years.

The company views the secp256k1 research as a rigorous test of its own architecture: taking a known quantum algorithm, a real cryptographic standard, and a specific machine—and linking it all together with verifiable numbers. This does not prove that a quantum attack on Bitcoin will be inevitable tomorrow. But a concrete benchmark for assessing the timeline of such a threat now exists.