Q-Day Could Arrive Before Quantum Computers Are Commercially Useful, EU Warns

In brief

• The EU's banking, insurance and markets regulators said an advanced quantum computer could undermine cryptography protecting communications, transactions, databases and blockchains.
• They warn that data captured today could be decrypted later, a tactic known as “harvest now, decrypt later.”
• The EU has recommended member states adopt a post-quantum cryptography migration strategy by the end of 2026.

An advanced quantum computer could undermine some of the cryptography systems used to secure communications, transactions, databases and blockchains, the European Union's three financial supervisors said in their autumn assessment of risks to the bloc's financial system.

The warning, from the joint committee of the European Banking Authority, the European Insurance and Occupational Pensions Authority and the European Securities and Markets Authority, highlighted that the threat could materialise “earlier than any viable commercial application,” meaning a machine capable of breaking encryption may exist before quantum computing is useful for anything else.

The assessment noted that encrypted material does not have to be read at the moment it is stolen. Information gathered now could be decrypted in future, the report said, a practice the industry calls “harvest now, decrypt later.” Anything intercepted today that still has value in a decade is already at risk.