Europol’s latest assessment flags quantum computing as a future risk to cryptocurrency ownership rather than to the underlying ledgers. While quantum machines capable of breaking public-key cryptography have not yet materialised, the agency stresses that proactive measures are needed to avoid a sudden loss of control over assets.
Exposure of Bitcoin wallets
The report identifies roughly 6.9 million bitcoin stored at addresses where the public key is already on-chain – a situation common among early-era wallets and long-dormant holdings. If a sufficiently powerful quantum processor were built, it could reverse-engineer the corresponding private key and move the funds.
Migration challenges
Transitioning the network to quantum-resistant cryptography involves more than swapping algorithms. A 2024 analysis estimates that converting every unspent transaction output (UTXO) to a post-quantum format would occupy at least 76 days of cumulative block space. Reserving a quarter of each block for the upgrade would extend the effort to about 300 days. New signature schemes are substantially larger – ten to 120 times the size of Bitcoin’s current ECDSA signatures – which would increase the data burden on the blockchain.
Industry response and timeline
Europol urges developers, miners, exchanges and users to begin a phased upgrade now, incorporating post-quantum cryptographic primitives and coordinated wallet updates. Researchers and institutions are already targeting 2029 as a deadline for a credible migration plan. IBM has projected that commercial quantum revenue could appear within the next two to four years, underscoring the narrowing window for action.
Why it matters
The immediate danger lies in the potential theft of assets from vulnerable wallets, not in the alteration of blockchain history. Without a coordinated shift to quantum-resistant security, a future quantum computer could silently empty billions of dollars worth of crypto held in exposed addresses, eroding confidence in digital assets and prompting regulatory scrutiny.
