Europol is urging cryptocurrency companies, policymakers and other organizations to begin preparing for quantum-computing threats, warning that wallet keys are the main point of exposure even though the hash functions underpinning blockchains remain largely resistant.
Wallet keys are the main vulnerability
The European Union’s law enforcement agency published two reports on Wednesday examining how more powerful quantum computers could affect cryptocurrencies and encrypted communications. The first, titled *Quantum Computing and Cryptocurrencies*, was produced by Europol’s European Cybercrime Centre.
At the center of the report is the cryptographic key pair used by cryptocurrency wallets. A private key authorizes transactions, while a public key allows the network to verify them. Europol warned that a sufficiently capable quantum computer could calculate a private key from an exposed public key. That could allow an attacker to spend funds without authorization, in what is often described as “Q-Day.”
The agency distinguished this threat from an attack on the blockchain’s underlying hash functions. Hashes link blocks and support mining, and Europol said that breaking a 256-bit hash would still require an “astronomically high” number of operations with foreseeable technology. Its conclusion was that cryptocurrencies are not expected to collapse solely because of quantum computing, but that the industry needs a proactive defense to preserve long-term security.
According to Decrypt, Europol recommended a phased move to quantum-resistant cryptography, together with stronger wallet security and improved key-management practices. The warning is particularly relevant to wallets whose public keys are already visible on a blockchain. Those keys cannot be protected retroactively, so the report says the only remedy is pre-emptive migration: transferring funds to newly created wallets before an attack becomes possible.
Glassnode estimated in May that 6.04 million Bitcoin, equivalent to 30.2% of the issued supply, had already had its public key exposed.
A difficult upgrade for Bitcoin
Moving to post-quantum protection would not be cost-free. Europol said signatures standardized by the U.S. National Institute of Standards and Technology are between 10 and 120 times larger than the ECDSA signatures currently used by Bitcoin. Larger signatures could consume more block space, push up fees and make transaction confirmations slower.
The report cited a 2024 study estimating that making every Bitcoin unspent transaction output quantum-safe would require at least 76 days of cumulative network downtime. If the work used only 25% of each block, the study estimated that the process could take about 300 days.
The timetable for quantum development remains uncertain, but the reports point to several indicators. IBM’s roadmap targets a fault-tolerant quantum computer by 2029, while Microsoft also expects scalable quantum computing by that year. A 2025 survey of 32 experts placed the probability of a machine breaking RSA-2048 encryption within 24 hours during the next decade at 28% to 49%.
Europol also noted that Google research published in March, along with an AI-assisted competition in September, reduced estimates of the resources needed to attack the elliptic-curve cryptography used by Bitcoin.
Preparatory work is already being discussed across the sector. Coinbase’s quantum advisory council called on developers in June to start post-quantum migration work. Ripple and the Stellar Development Foundation have published migration roadmaps. In July, nine companies, including BlackRock, Coinbase and Strategy, pledged a combined $15 million over three years for Bitcoin security research, including quantum defenses.
“Harvest now, decrypt later”
Europol’s second report, *Harvest Now, Decrypt Later*, was developed with Spain’s University Carlos III of Madrid. It examined the possibility that attackers could collect encrypted information today and decrypt it once sufficiently powerful quantum computers become available.
The report found that protocols including TLS, SSH and OpenPGP could be susceptible, although the level of risk depends on configuration and key-management practices. Europol said there is currently no clear evidence that this method is being used systematically at scale. Because of the resources involved, government communications and confidential business information appear to be the most plausible targets.
For cryptocurrency payments, however, Europol described real-time interception as a more immediate concern than the later decryption of stored data. A “just-in-time” attack could involve deriving a private key during the brief period after a transaction exposes a public key but before the transaction is confirmed.
The agency recommended a European Commission-led working group involving Europol, the EU cybersecurity agency ENISA and the EU Anti-Money Laundering Authority. The group would regularly brief policymakers. The EU’s NIS Cooperation Group has recommended that member states adopt a post-quantum migration strategy by the end of 2026. NIST has proposed deprecating today’s most common public-key configurations by 2030 and phasing out classical public-key cryptography by 2035.
Current crypto market picture
Moneyiar market data at 09:24 on October 8, 2026, showed Cardano (ADA) at $0.2517381456, down 1.33% over 24 hours but up 2.05% over seven days. Polygon’s successor token, POL, was priced at $0.1013455488, down 1.05% in 24 hours and 9.32% over seven days. Quant (QNT) stood at $241.1569615096, down 4.39% over 24 hours and 17.75% over seven days.
