A quantum system built from 22,593 physical cat qubits could theoretically factor a 2048-bit RSA encryption key in 3.14 days, according to researchers at the French company Alice & Bob, working with scientists from the National Institute for Research in Digital Science and Technology (Inria), the French Alternative Energies and Atomic Energy Commission (CEA) and the University of Edinburgh, the website infohub.kz reports.
The study has been published as a preprint in the open archive of the International Association for Cryptologic Research (IACR Cryptology ePrint Archive). As ScienceAlert notes, it points to a fundamentally different scale of threat to conventional data-protection standards.
RSA-2048 encryption underpins the security of the modern internet, protecting online banking, email and digital signatures. The standard relies on the computational difficulty of factoring enormous numbers into primes. Cracking it with Peter Shor's algorithm requires powerful quantum resources.
Experts had previously assumed that such a task would require millions of transmons, but an optimized architecture built on 22,593 physical qubits cuts those requirements by roughly 40 times. Linking ten such machines together could reduce the time needed to break a key to one hour and 15 minutes.
The authors also assessed the vulnerability of Bitcoin's elliptic-curve cryptography (secp256k1). Breaking that algorithm would require 29,588 qubits and about 62 minutes, which is well above the 10-minute block-formation interval and currently keeps transactions protected.
The scientists stress that the calculations are purely theoretical: quantum systems on this scale do not exist today. The largest experimental array, at the California Institute of Technology, contains 6,100 laser qubits but is not a working processor. The researchers recommend that the IT sector move to post-quantum cryptography in advance.