EU Watchdogs Warn Quantum Computers Could Break Blockchain Cryptography

European financial watchdogs have warned that advanced quantum computers could compromise the cryptography securing blockchains and transactions. The Joint Committee of European Supervisory Authorities, comprising EBA, EIOPA, and ESMA, emphasized that such risks may emerge before any commercially viable quantum applications become practical.

The warning is based on a risk update published in September 2026, which noted that quantum computing could improve financial processes but also weaken cryptography used throughout the financial infrastructure. The authorities stressed that 'risks posed could materialise faster than any commercially viable application.'

According to ESMA's technical analysis, sufficiently advanced quantum computers could use Shor's algorithm against public-key schemes, including those used by Bitcoin for ownership and transaction authorization.

CryptoQuant founder Ki Young Ju estimated in February that approximately 6.89 million BTC may face future quantum exposure risks, while Glassnode measured 6.04 million BTC as having public-key exposure at rest.