Banking data in France: a quantum computer could break encryption in three days

Published 2026-11-09

According to an article published by the magazine Science et Vie, the encryption used to protect banking data in France could be broken in just three days by a quantum computer with 22,593 qubits. Encryption is the method that makes information unreadable to people who are not entitled to access it. It is used every day to secure payments, online accounts, and exchanges between banks and their customers.

Quantum computers operate on principles that are very different from those of classical computers. Their basic unit, the qubit, can take several states at the same time, which allows them, in theory, to solve certain calculations much faster. For now, machines of this type are still far from this level of power. Researchers estimate that a computer capable of breaking current encryption methods does not yet exist, but the question is already a concern for cybersecurity specialists.

Faced with this risk, experts are working on new so-called "post-quantum" encryption methods, which should be able to withstand future quantum computers. Financial institutions and security authorities are following this work and are gradually preparing the transition to these new protections. This change will take time, as it affects a very large number of computer systems.

In short, the estimate presented in this article rests on one assumption: the arrival of a very powerful quantum computer. It does not mean that an attack of this kind has already taken place. The scientific progress in this field will need to be monitored in order to measure how the real risk to banking data evolves.

Sources: Science et vie

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