EU Regulators Warn Quantum Computing Could Break Blockchain Encryption Sooner Than Expected

European regulators say a powerful quantum computer could weaken the encryption that protects blockchains, and the danger may appear before the technology has any real commercial use. The warning comes from the Joint Committee of the European Supervisory Authorities, which includes the EBA, ESMA and EIOPA. It was published Wednesday in their Autumn 2026 risk and vulnerabilities report.

Bitcoin Quantum Risk: 6.9 Million BTC Exposed

Coindesk report, CryptoQuant estimates that about 6.9 million bitcoin, worth roughly $586 billion, could be vulnerable. The most exposed coins are old Satoshi era holdings in legacy or reused addresses, where the public key is already visible onchain. A strong enough quantum machine could use it to work out the private key. Many other coins hide the key behind a hash, so they face less risk for now.

Quantum Computing Timeline and Harvest Now, Decrypt Later Attacks

The report gives no dates, but an IBM report says quantum computing could be in use within four years or less. Regulators also warned that data collected today could be decrypted later.

Post-Quantum Cryptography Roadmap

Bitcoin cannot update its security as quickly as a bank. Moving to quantum resistant signatures needs network wide consensus, and holders of exposed coins must move them first. The European Commission wants member states to start transitioning by the end of 2026, with high-risk uses protected by 2030.