TLDR: EU regulators warn quantum threats may reach blockchain security before quantum computing sees mass adoption. Coinbase advisers estimate 7 million BTC face quantum risk, including 5 mil
European financial regulators have warned that quantum computing could threaten blockchain security before the technology becomes widely commercially available. The warning came from the Joint Committee of the European Supervisory Authorities, which includes the EBA, ESMA and EIOPA.
In its Autumn 2026 risk update, the committee said advanced quantum systems could weaken cryptography protecting transactions, communications, databases and distributed ledgers. That timing matters as financial institutions may face security risks before quantum computing reaches mass adoption.
Regulators therefore want preparation to begin well in advance. The technology could also support financial applications, including pricing, compliance monitoring and fraud detection. However, regulators emphasized that stronger computing power creates new cryptographic vulnerabilities.
Bitcoin’s main exposure involves digital signatures built on public-key cryptography, which protects ownership and authorizes transactions across the blockchain. A sufficiently capable fault-tolerant quantum computer using algorithms such as Shor’s could theoretically derive private keys from exposed public keys.
That capability could allow unauthorized transactions from affected addresses. However, no existing quantum computer has the scale and reliability required to break Bitcoin’s cryptography.
The longer-term exposure remains significant as many public keys have already been revealed through previous transactions and address reuse. Coinbase’s Independent Advisory Board estimated in June that roughly 7 million BTC could eventually face quantum-related risks.
Around 5 million BTC were linked to address reuse, including holdings associated with some large exchange cold wallets. Recent research has also lowered estimates for certain computational resources involved in theoretical cryptographic attacks.
A September study cited by The Block produced a circuit using 1,151 logical qubits and 1.30 million Toffoli gates. Researchers stressed that the circuit does not represent a complete Bitcoin attack and excludes substantial physical error-correction requirements.
Europe has already moved toward post-quantum cryptography as regulators seek to reduce future vulnerabilities across financial infrastructure. EU member states adopted a coordinated migration roadmap in June 2025 covering the transition toward cryptographic systems designed to resist quantum attacks.
As a result, the roadmap calls for every member state to begin migration by the end of 2026. High-risk systems and critical infrastructure should complete their transition no later than 2030 under the coordinated plan.
The United States has taken similar action through the National Institute of Standards and Technology. NIST finalized three post-quantum standards in 2024, including ML-KEM, ML-DSA and SLH-DSA, and recommends that organizations begin deployment now.
For blockchain networks, migration could prove more complex as signature upgrades may require protocol changes, ecosystem coordination and users moving assets from vulnerable addresses.
That creates a timing challenge. Although a practical quantum attack remains unavailable today, regulators are treating preparation as an immediate security issue rather than a distant technology problem.
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