Ledger CTO says estimate that only 30% of BTC faces quantum risk is inaccurate

Ledger CTO Charles Guillemet challenged an analysis suggesting only about 30% of Bitcoin is exposed to quantum-computing attack risk, stressing that public keys can be exposed through xpubs, devices, PSBTs, logs and backups, not just through spent on-chain outputs. Citing Glassnode data, Guillemet said about 30.2% of BTC has exposed spent public keys on-chain, but added that public keys are also revealed during BTC transfers before transactions are confirmed. Guillemet emphasized that if sufficiently fast quantum computers emerge, hiding public keys alone would not be enough and Bitcoin would ultimately need to transition to a quantum-resistant cryptographic system.