European financial regulators have issued a warning that advanced quantum computers could potentially undermine the cryptography used to secure blockchains, posing a significant threat to the integrity of blockchain technology. The warning comes 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).
The report highlights that approximately 6.9 million Bitcoin, worth roughly $586 billion, are currently vulnerable to this threat. This vulnerability arises because older or reused Bitcoin addresses may have their public keys already exposed on the blockchain, making them susceptible to quantum computing attacks.
The European Union (EU) warning does not indicate that a quantum computer capable of breaking Bitcoin's cryptography currently exists. However, the transition to quantum-resistant security measures would require network-wide consensus and the transfer of exposed coins. The European Commission has urged member states to begin post-quantum transitions by the end of 2026.
The report from the ESAs states that threats could materialize earlier than any viable commercial application of quantum computing. A recent report by IBM suggests that quantum computing could be commercially viable within four years or less. The Satoshi-era Bitcoin held in older, legacy addresses or reused addresses faces greater risk if quantum computing advances. In these cases, the public key may already be visible on the blockchain, allowing a sufficiently powerful quantum computer to derive the private key and take control of the coins.
The European financial watchdogs emphasize that information gathered today could be decrypted later in so-called "harvest now, decrypt later" attacks. The European Commission's post-quantum roadmap calls for member states to begin transitioning by the end of 2026, with high-risk use cases to be protected by 2030.
