The agency aimed to draw a clear distinction often lost in warnings about quantum computing: the hash functions that help secure a blockchain’s history, including bitcoin mining, remain far more resistant to quantum attacks than the public-key cryptography used to control wallets.
“Cryptocurrencies will not collapse due to quantum computing,” Europol said. The immediate concern is ownership of the assets held in wallets, not whether a quantum computer could rewrite the bitcoin blockchain.
That distinction is more critical for addresses from the earliest days of Bitcoin – referred to as the “Satoshi era” – whose public keys have already become visible onchain. A powerful enough quantum computer could use those keys to drive the corresponding private key. Roughly 6.9 million bitcoin sit in addresses with exposed public keys, including early pay-to-topublic-key outputs and many long-dormant holdings.
Europol said exposed keys cannot be made safe retroactively, an issue that has sparked massive debates and controversies across the bitcoin community as the dilemma of whether or not to freeze BTC in Satoshi-era wallets increases as the quantum threat nears.
The more difficult task today is updating the network itself. Europol cited a 2024 study estimating that converting every bitcoin unspent transaction output, or UTXO, to a quantum-resistant format would require at least 76 days of cumulative block space. Reserving 25% of each block for the migration, that study adds, would stretch that process to about 300 days.