EU regulators warn quantum computing could threaten blockchain encryption

European financial supervisors have issued a warning that future quantum computers could break the cryptographic algorithms that protect blockchain networks. The alert highlights a potential risk to roughly 6.9 million Bitcoin, valued at about $586 billion, if the technology becomes capable of deriving private keys from exposed public keys.

Quantum risk to legacy Bitcoin addresses

Older Bitcoin outputs that use pay‑to‑public‑key (P2PK) scripts or reused addresses already reveal their public keys on the blockchain. A sufficiently powerful quantum computer could, in theory, use those public keys to calculate the corresponding private keys and gain control of the funds. Outputs that remain hidden behind a cryptographic hash are less immediately vulnerable.

Implications for the Bitcoin network

Transitioning Bitcoin to quantum‑resistant signatures would require consensus across the entire network and the migration of any exposed coins before an attack becomes feasible. The European Supervisory Authorities (EBA, ESMA, and EIOPA) note that “harvest‑now, decrypt‑later” attacks could collect data today for decryption once quantum capabilities mature.

EU post‑quantum roadmap

The European Commission’s post‑quantum strategy calls on member states to start transitioning high‑risk use cases by the end of 2026, with broader protection targets set for 2030. The warning does not claim that a quantum computer capable of breaking Bitcoin’s cryptography exists now, but it stresses the need for proactive measures.