EU financial watchdogs warn quantum computing poses imminent threat to blockchain encryption
The warning brings renewed urgency to the debate over how bitcoin should deal with legacy addresses whose public keys are already exposed onchain.
European financial authorities warned that an advanced quantum computer could undermine cryptography used to secure blockchains, saying the threat could emerge before the technology has a viable commercial application.
The warning from the Joint Committee of the European Supervisory Authorities (ESAs), which includes the European Banking Authority (EBA), European Securities and Markets Authority (ESMA) and European Insurance and Occupational Pensions Authority (EIOPA), brings fresh urgency to a long-running question for bitcoin of whether to freeze or not freeze the BTC in legacy wallets. In the event that quantum computers one day do become capable of breaking bitcoin’s cryptography, roughly 6.9 million bitcoin, worth roughly $586 billion, are currently vulnerable, according to Cryptoquant.
“Threats could materialize earlier than any viable commercial application,” the authorities said in their Autumn 2026 Risk and Vulnerabilities report released Wednesday. An advanced quantum computer “could undermine some cryptography systems widely used to secure communications, transactions, databases and blockchains,” according to the report..
The Satoshi-era bitcoin held in older, legacy addresses or reused addresses could face greater risk if quantum computing advances. In those cases, the public key may already be visible on the blockchain. A sufficiently powerful quantum computer could use it to derive the private key and take control of the coins.