EU law enforcement authorities are calling on cryptocurrency developers, exchanges and users to begin preparing for post-quantum security upgrades before quantum computers can potentially enable unauthorized transfers.
Europol said in a report published Wednesday that crypto wallets are likely to represent the primary vulnerability to future quantum-computing attacks, rather than the underlying blockchains themselves.
Quantum machines capable of carrying out these attacks do not currently exist, and Europol did not provide a timeline for when they might become practical. Instead, the agency said the more likely scenario is “proactive adaptation, rather than systemic collapse.”
The European law enforcement agency recommended that the crypto industry begin a gradual migration through wallet upgrades, post-quantum cryptographic systems and cooperation between developers, miners, exchanges and users.
Bitcoin researchers and institutions are increasingly identifying 2029 as a target date for having credible plans to migrate toward quantum-resistant systems. IBM said in July that it expects quantum computing to produce significant commercial revenue within the next two to four years.
A sufficiently advanced quantum computer could potentially calculate a private key from its corresponding public key and use it to move the funds controlled by that wallet, according to Europol’s European Cybercrime Center in its report, “Quantum Computing and Cryptocurrencies.”
Wallet Keys Are the Main Quantum Vulnerability
Europol emphasized a distinction that can be overlooked in broader discussions about quantum threats. The hash functions that protect blockchain history and support processes such as Bitcoin mining are considerably more resistant to quantum attacks than the public-key cryptography responsible for controlling wallet funds.
“Cryptocurrencies will not collapse due to quantum computing,” Europol said. The primary concern is whether attackers could gain control of assets stored in vulnerable wallets, rather than whether quantum computers could rewrite Bitcoin’s historical blockchain data.
The issue is particularly significant for early Bitcoin addresses associated with the so-called Satoshi era, where public keys have already been exposed on-chain. A sufficiently powerful quantum machine could potentially derive the corresponding private keys from those public keys.
Approximately 6.9 million BTC are held in addresses with exposed public keys, including early pay-to-public-key outputs and numerous long-dormant holdings.
According to Europol, once a public key has been exposed, the associated cryptographic risk cannot be reversed retroactively. That limitation has fueled debate within the Bitcoin community over how to handle Satoshi-era holdings and whether such coins should eventually be frozen as quantum capabilities advance.
Migrating Bitcoin to Quantum-Resistant Cryptography
Updating the network itself presents a separate challenge. Europol cited a 2024 study estimating that moving every Bitcoin unspent transaction output, or UTXO, into a quantum-resistant format would require at least 76 days of cumulative block space.
If only 25% of each block were allocated to the migration process, the study estimated that the transition could take approximately 300 days.
Post-quantum signature systems also create additional data demands. The report said some newer signature schemes can be between 10 and 120 times larger than Bitcoin’s existing Elliptic Curve Digital Signature Algorithm, or ECDSA, signatures.
ECDSA is the cryptographic system used to demonstrate ownership of Bitcoin and authorize transactions that transfer funds across the network.
The central problem for Bitcoin, therefore, is not simply developing replacement cryptography. The larger challenge is coordinating a worldwide decentralized network so that wallets and other infrastructure adopt quantum-resistant technology before sufficiently powerful quantum computers can exploit exposed keys.
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