About 6.04 million bitcoin, or 30.2 percent of the supply issued so far, sit in addresses whose public keys are already visible on the blockchain, by Glassnode’s estimate. A report published by Europol on Wednesday explains why that number matters.
The study, from the agency’s European Cybercrime Centre, calls cryptocurrency wallets the primary point of exposure to quantum threats, Decrypt reported. A powerful enough quantum computer could derive the private key from an exposed public key and spend the funds.
The chains themselves fare better. Europol says the hash functions that link blocks and underpin mining are largely resistant, because breaking a 256-bit hash would take a number of operations it calls astronomically high.
No date is given for when such a machine might exist. The report points to others’ timelines instead. IBM and Microsoft both name 2029 for fault-tolerant or scalable systems, and a 2025 survey of 32 experts put the odds of RSA-2048 encryption being broken within a decade at 28 to 49 percent.
Fixing it is costly. Post-quantum signatures are 10 to 120 times larger than the ones Bitcoin uses today. A 2024 study cited in the report estimated that moving every unspent output would need at least 76 days of cumulative network downtime.
Europol recommends a phased move to quantum-resistant cryptography. A companion report on attackers who harvest encrypted data now to decrypt later proposes a working group led by the European Commission, with Europol, ENISA and the EU’s anti-money-laundering authority.
The gap is ownership. Only Bitcoin’s developers, miners and holders can change Bitcoin, and coins whose owners have died or lost their keys cannot be moved by anyone. Decrypt’s account of the report does not say what should happen to those.
