Overview
- ARK Invest and Unchained assess about 34.6% of BTC as theoretically exposed under a future quantum break of elliptic‑curve cryptography.
- The vulnerable slice includes roughly 5 million BTC from address reuse, around 1.7 million BTC in legacy P2PK believed largely lost, and about 200,000 BTC in Taproot outputs.
- The authors say today’s quantum machines are far from capable, with real‑time key breaks needing roughly 2,330 logical qubits and tens of millions to billions of gates.
- Risk is framed as a staged, gradual progression likely to disrupt broader internet security before Bitcoin, offering warning signals and time to adapt.
- Mitigations under discussion include discouraging key reuse, post‑quantum signatures, and proposals such as BIP‑360’s P2MR, with investor takeaways focused on a structural tail risk as dormant coins and custody standards may reprice; CoinCentral estimates about 6.9 million BTC (~$483B at $70,000) could be in the vulnerable cohort.