Europol warns exposed Bitcoin wallet keys lack quantum computing defences

A report from Europol's cybercrime unit warns that future quantum computers could deduce private keys from exposed public keys, potentially allowing attackers to authorise illicit transfers. The agency clarified that the risk is confined to specific exposed addresses rather than the underlying network, as the hashing algorithms securing Bitcoin's blockchain remain significantly more resilient.

According to Glassnode figures cited in the report, approximately 6.04 million BTC—representing 30.2% of the circulating supply and valued at roughly $502 billion at an $83,050 price—are currently stored in vulnerable conditions. The exposed holdings primarily reside in reused addresses, exchange-managed accounts, Taproot addresses, and legacy formats used in early transactions, where public keys become visible upon broadcasting an outgoing payment.

Europol notes that the only remedy for holders with exposed keys is to transfer their funds to fresh addresses prior to the advent of quantum-capable attacks. The report also highlights logistical hurdles to a network-wide upgrade, indicating that quantum-resistant signatures would be 10 to 120 times larger than current formats, requiring between 76 and 300 days of transaction capacity to execute a comprehensive migration.