A future quantum-computing threat to cryptocurrencies is more likely to target vulnerable wallets than to bring down the blockchains themselves, Europol said in a report published Wednesday. The European Union’s law-enforcement agency is urging developers, exchanges, miners and users to begin a coordinated, phased migration to quantum-resistant security before sufficiently powerful machines exist.
Wallet ownership is the central risk
According to CoinDesk, Europol’s European Cybercrime Center said a quantum computer capable of the relevant attack could derive a private key from a wallet’s exposed public key. The attacker could then use that private key to authorize transfers from the associated address.
Such computers do not currently exist, and Europol did not estimate when they might become available. The agency nevertheless argued that preparation should start now, describing proactive adaptation as more likely than a collapse of cryptocurrency systems.
The warning focuses on the cryptography used to control funds rather than the mechanisms that preserve a blockchain’s transaction history. Europol said the hash functions supporting blockchain security, including those involved in Bitcoin mining, are considerably more resistant to quantum attacks than the public-key systems used to prove wallet ownership.
In other words, the immediate concern is not that a quantum computer could rewrite Bitcoin’s blockchain. It is that an attacker could obtain the private key needed to spend assets from a wallet whose public key is already visible.
Millions of bitcoin are in exposed addresses
The issue is particularly sensitive for some of Bitcoin’s earliest addresses, often associated with the “Satoshi era.” Their public keys have already appeared onchain, leaving the corresponding holdings potentially exposed if quantum technology becomes powerful enough.
Europol estimates that about 6.9 million bitcoin are held at addresses with exposed public keys. That figure includes early pay-to-public-key outputs and many wallets that have remained inactive for long periods.
Once a public key has been exposed, Europol said, it cannot be made safe retroactively. That creates a difficult question for the Bitcoin community: whether vulnerable holdings, including coins in early and dormant wallets, should eventually be frozen as the technology develops. The source material says this issue has already generated significant debate and controversy, but it does not identify a decision or policy to freeze those assets.
Researchers and institutions increasingly regard 2029 as the point by which credible quantum-resistant migration plans should be in place. IBM said in July that it expects quantum computing to produce significant commercial revenue within the next two to four years. Neither reference establishes that an attack on cryptocurrency will occur by then.
A networkwide migration would be difficult
Europol’s recommended response includes upgrading wallets, adopting post-quantum cryptography and coordinating action across the cryptocurrency industry. The challenge is that Bitcoin is a global, decentralized network, so replacing its current security standards requires broad participation rather than a single company’s decision.
A 2024 study cited by Europol estimated that converting every Bitcoin unspent transaction output, or UTXO, into a quantum-resistant format would require at least 76 days of cumulative block space. If 25% of each block were reserved for the process, the migration could take about 300 days.
The replacement signatures also create a capacity issue. The report said new post-quantum signature schemes can be 10 to 120 times larger than Bitcoin’s existing Elliptic Curve Digital Signature Algorithm signatures. ECDSA is the cryptographic system used to demonstrate ownership of bitcoin and authorize transactions.
That means the problem is not simply identifying an alternative form of cryptography. Developers, miners, exchanges and users would need to agree on a transition and implement it across the network before exposed wallets became attractive targets. Europol’s recommendation is therefore for a phased migration rather than an immediate claim that existing blockchains are failing.
Moneyiar market picture
Moneyiar data at 09:04 on October 8, 2026, show mixed performance among the listed assets:
- Polygon (prev. MATIC), now shown as POL, was priced at $0.1016148077, down 0.85% over 24 hours and 8.93% over seven days.
- Quant (QNT) stood at $241.9185905648, down 4.12% in 24 hours and 18.26% over seven days.
- Celestia (TIA) traded at $0.4800982533, up 5.92% over 24 hours and 7.85% over seven days.
These market movements are separate from Europol’s long-term warning about quantum security. The report addresses the future protection of cryptocurrency ownership and transaction authorization, not a current quantum-computing attack or a forecast for the prices of the assets listed above.
