Europol’s European Cybercrime Centre (EC3) published two reports on October 7 identifying crypto wallets as “the primary point of exposure to quantum threats” and urging everyday users to act. The agency’s newsroom announcement carries both papers, Quantum Computing and Cryptocurrencies and Harvest Now, Decrypt Later.
For a holder, the practical takeaway is narrower than the headline. A future quantum computer running Shor’s algorithm could derive a private key from a public key that has already been shown on-chain, which would let an attacker spend the funds. Wallets whose keys are still hidden face a different, shorter risk: a “just-in-time” attack during the seconds between a transaction exposing its public key and its confirmation. The blockchain data that links blocks, including mining, is largely quantum-safe; Europol says breaking a 256-bit hash would take an astronomically high number of operations with foreseeable technology.
The report is blunt about exposed keys: “the only solution is pre-emptive migration,” meaning moving funds to a fresh wallet with new keys before any attack. That cannot be done retroactively once a large-scale quantum computer exists, because the exposed public keys stay exposed. Glassnode’s estimate, cited in the report, put 6.04 million BTC, about 30.2% of issued supply, in the exposed-key category as of May. CryptoQuant’s separate count of Bitcoin in legacy or reused addresses, which uses a different methodology, came to roughly 6.9 million BTC, about $586 billion at the time of the reports.
Europol framed the migration recommendation as a phased, systematic move addressed to blockchain developers, wallet providers, policymakers and everyday users, alongside better wallet security and stronger key management practices. The reports deliberately name no specific asset or platform, so the advice applies across the crypto spectrum.
Two cautions belong next to the advice. NIST-standardized post-quantum signatures run 10 to 120 times larger than the ECDSA signatures Bitcoin uses today, a size jump the report warns could crowd block space and raise fees, so wallet providers are still working out what a migrated wallet looks like in practice. And Europol is not predicting collapse: the report concludes cryptocurrencies will not collapse due to quantum computing and recommends proactive defence rather than panic.
The urgency comes from timing, not imminent capability. IBM’s roadmap targets a fault-tolerant quantum computer by 2029, and Microsoft expects scalable quantum computing the same year. NIST has proposed deprecating today’s most common public-key configurations by 2030 and phasing out classical public-key cryptography by 2035. A 2024 study cited in the report estimated that migrating every unspent Bitcoin output would take at least 76 days of cumulative network downtime, which is why Europol wants the transition started while there is still room to schedule it.
