European financial regulators have cautioned that sophisticated quantum computers might eventually crack the cryptography safeguarding distributed ledgers, pointing out that this hazard could materialize prior to the technology reaching practical commercial viability.
This alert issued by the Joint Committee of the European Supervisory Authorities (ESAs)—comprising the European Banking Authority (EBA), the European Securities and Markets Authority (ESMA), and the European Insurance and Occupational Pensions Authority (EIOPA)—adds immediate urgency to a long-standing debate within the bitcoin community regarding whether to freeze or not freeze legacy wallet holdings. Should quantum machines eventually gain the capability to break bitcoin encryption, approximately 6.9 million coins carrying an estimated value of $586 billion remain exposed, according to Cryptoquant.
In their Autumn 2026 Risk and Vulnerabilities report published on Wednesday, the agencies noted that dangers might surface ahead of any commercial utility. An advanced quantum system “could undermine some cryptography systems widely used to secure communications, transactions, databases and blockchains,” the document states.
Even though the assessment avoids specifying precise timelines for quantum hardware commercialization, a recent IBM study projects implementation within four years or less.
Legacy bitcoin assets dating back to the Satoshi era, stored within older addresses or repeatedly used destinations, face elevated danger as quantum technology progresses. Under those circumstances, the public key might already be exposed directly on the blockchain. A sufficiently advanced quantum processor could leverage this data to calculate the corresponding private key and seize control of the funds.
This vulnerability does not extend uniformly to all inactive wallets. Many unspent transaction outputs continue to conceal their public keys behind cryptographic hashes, keeping them better protected for the time being. Vintage pay-to-public-key outputs alongside reused addresses differ because their public keys already exist on-chain.
While the European Union alert stops short of declaring that a quantum machine capable of cracking bitcoin security exists today, the network cannot simply patch its defenses the way traditional financial institutions do. Transitioning toward quantum-resistant signatures demands absolute network-wide consensus, and owners of vulnerable tokens would need to transfer their balances prior to any successful exploit.
European regulatory watchdogs additionally warned that data intercepted today risks being decrypted at a later date through so-called harvest-now-decrypt-later operations. The European Commission post-quantum roadmap instructs member governments to initiate upgrades by the conclusion of 2026, ensuring high-risk applications achieve protection by 2030.
Originally published at https://www.coindesk.com/tech/2026/09/24/eu-financial-watchdogs-warn-quantum-computing-poses-imminent-threat-to-blockchain-encryption.
