EU financial supervisors warn quantum advances could weaken blockchain cryptography
EU financial supervisors warned that quantum advances could weaken blockchain cryptography before commercial quantum applications arrive, and urged an EU post-quantum migration strategy by end-2026.
Why it matters
Bringing a post-quantum change to Bitcoin would require networkwide agreement to replace current signatures and a policy for coins in legacy wallets. Decrypt reported an end-2026 EU migration-strategy target, while Crypto.News said high-risk uses should be protected no later than 2030; Cointelegraph reported that no existing computer can perform the described attack.
Key facts
The Joint Committee of the European Supervisory Authorities warned in its Autumn 2026 risk update that quantum advances could undermine cryptography used for communications, transactions, databases and blockchains, with the threat possibly emerging before viable commercial applications.
Reported by Cointelegraph
Crypto.News reported CryptoQuant founder Ki Young Ju's estimate that 6.89 million BTC may face public-key exposure relevant to a future quantum attack.
6,890,000 BTCDisputed figureReported by Crypto.News
CoinDesk and Bitcoin Insider said a future quantum computer could derive a private key from a public key already visible onchain; older or reused Bitcoin addresses are more exposed, while many other unspent outputs do not reveal the public key until a transaction is made.
Reported by Cointelegraph
Decrypt reported an end-2026 post-quantum strategy target; Crypto.News said migration should begin by 2026 and high-risk uses should be protected no later than 2030, while CoinDesk said the European Commission urged transitions to begin by the end of 2026.
Reported by CoinDesk
Cointelegraph reported that Jameson Lopp and five co-developers proposed in February to phase out Bitcoin's current signatures and restrict spending on unmigrated funds five years after activation, but the proposal has not been adopted.
Reported by Cointelegraph
What happened
Cointelegraph, CoinDesk, Crypto.News, Bitcoin.com News and Decrypt reported that the Joint Committee of the European Supervisory Authorities, which includes the European Banking Authority, the European Insurance and Occupational Pensions Authority and the European Securities and Markets Authority, warned in its Autumn 2026 risk update that quantum advances could undermine cryptography used for communications, transactions, databases and blockchains, with the threat possibly emerging before viable commercial applications. Decrypt and Bitcoin.com News reported the regulators' 'harvest now, decrypt later' concern, while Cointelegraph reported that no existing computer is capable of the attack it described. Reported estimates of exposed Bitcoin differ, as CoinDesk cited about 6.9 million BTC, worth roughly $586 billion, while Crypto.News attributed 6.89 million BTC to CryptoQuant founder Ki Young Ju. CoinDesk and Bitcoin Insider said older or reused Bitcoin addresses are more exposed when their public keys are already visible onchain, because a future quantum computer could derive the corresponding private keys, which could then authorize spending. Decrypt reported an end-2026 post-quantum strategy target; Crypto.News said migration should begin by 2026 and high-risk uses should be protected no later than 2030, while CoinDesk said the European Commission urged transitions to begin by the end of 2026. Bitcoin's migration path remains unsettled, as Cointelegraph reported that Jameson Lopp and five co-developers proposed in February to phase out current signatures and restrict spending on unmigrated funds five years after activation, although the proposal has not been adopted; CoinDesk and Crypto.News said consensus and the handling of legacy coins remain unresolved.
How the story developed
- First report
First report by Cointelegraph
EU watchdogs warn quantum computers could pick crypto’s locks
- Update
Bitcoin developers propose staged signature migration
Cointelegraph reported that Jameson Lopp and five co-developers proposed phasing out Bitcoin's current signatures and restricting spending on unmigrated funds five years after activation.
- Update
Google Quantum AI revises a physical-qubit estimate
Cointelegraph reported that in March Google Quantum AI researchers estimated that breaking cryptography used by many cryptocurrencies could require about 20 times fewer physical qubits than earlier estimates.
- Update
Cointelegraph reports EU supervisors' quantum warning
Cointelegraph reported that the three EU financial supervisors warned that quantum computing could weaken cryptography securing blockchains.
- Independent corroboration
Independently corroborated by CoinDesk
EU financial watchdogs warn quantum computing poses imminent threat to blockchain encryption
- Update
CoinDesk adds a Bitcoin exposure estimate
CoinDesk reported that about 6.9 million BTC, worth roughly $586 billion, could be exposed to future quantum attacks.
- Update
Crypto.News reports Ki Young Ju's BTC estimate
Crypto.News reported that 6.89 million BTC may face public-key exposure relevant to a future quantum attack and cited migration dates for 2026 and 2030.
- Official statement
Official statement from Bitcoin.com News
AI Threat: Web3 Told to Add Spending Caps and Circuit Breakers Onchain
How coverage built up
Independent sources over time, counted the way the consensus panel counts them: a republication of a wire story does not move the line.
- 23 Sept 2026, 12:22 UTC: Cointelegraph — 1 independent source, 1 reports
- 24 Sept 2026, 09:32 UTC: CoinDesk — 2 independent sources, 2 reports
- 24 Sept 2026, 10:24 UTC: Crypto.News — 3 independent sources, 3 reports
- 24 Sept 2026, 10:30 UTC: Bitcoin.com News, official — 4 independent sources, 4 reports
- 24 Sept 2026, 11:05 UTC: Decrypt — 5 independent sources, 5 reports
- 24 Sept 2026, 12:53 UTC: Bitcoin Insider — 6 independent sources, 6 reports
- 24 Sept 2026, 20:40 UTC: Bitcoin Insider — 7 independent sources, 8 reports
Affected entities
Original sources
| Publisher | Report | Role | Published |
|---|---|---|---|
| Bitcoin.com News Company, official | AI Threat: Web3 Told to Add Spending Caps and Circuit Breakers Onchain | Independent | |
| Cointelegraph Crypto media | EU watchdogs warn quantum computers could pick crypto’s locks | Original | |
| CoinDesk Crypto media | EU financial watchdogs warn quantum computing poses imminent threat to blockchain encryption | Independent | |
| Decrypt Crypto media | Q-Day Could Arrive Before Quantum Computers Are Commercially Useful, EU Warns | Independent | |
| Crypto.News Crypto media | EU watchdogs warn quantum computers could hit blockchains | Independent | |
| Bitcoin Insider Aggregator | EU Regulators Warn Quantum Computing Could Threaten Blockchain Security | Syndicated | |
| Bitcoin Insider Aggregator | Quantum-Proofing Crypto: Why Blockchain Migration Is an Operational Problem | Syndicated | |
| Bitcoin Insider Aggregator | Quantum-Proofing Crypto: Why Blockchain Migration Is an Operational Problem | Syndicated |
Related events
Carlo Comporti Appointed ESMA Chair Effective November 1, 2026
The Council of the European Union confirmed Carlo Comporti as the new ESMA chair starting November 1, 2026, succeeding Verena Ross after her five-year term.
Banks double presence on EU MiCA crypto register to nearly 23% share
Banks roughly doubled their count on ESMA's MiCA register to about 80 between late June and mid-September, lifting their share of listed crypto providers to nearly 23%.
ESMA names AI and tokenization a Union-wide supervisory priority from 2027
ESMA said on Wednesday it will make AI and tokenization the first focus of a new Union-wide supervisory priority from 2027, with national regulators mapping client-facing uses and checking selected firms.
ESMA and regulators in France, Germany and Greece question Binance over MiCA reverse solicitation
ESMA and national regulators in France, Germany and Greece are examining whether Binance properly relied on MiCA's reverse solicitation exemption to keep serving EU customers after July 1 without a licence.
ESMA bars EU crypto providers from non-MiCA stablecoins with January 8, 2027 deadline and launches tokenized collateral consultation
ESMA ordered EU crypto firms to wind down services for non-MiCA stablecoins like USDT by January 8, 2027, while separately opening a consultation on tokenized collateral risks with a January 15, 2027 response deadline.
ESMA directs EU regulators to clear non-MiCA stablecoin exposures by January 8, 2027
ESMA issued an opinion giving national supervisors three months to wind down crypto firm services for stablecoins not authorized under MiCA, with a final deadline of January 8, 2027.