A large, fault-tolerant quantum computer could in principle derive a private key from a public key. No such machine exists today.
What is exposed
- Coins whose public key is already visible on-chain: very old pay-to-public-key outputs, reused addresses, and Taproot key-path outputs.
- Coins in addresses never spent from show only a hash, which quantum computers do not break efficiently.
- proof of work mining is far less affected.
What is being prepared
- NIST approved post quantum standards FIPS 203, 204 and 205 on 13 Aug 2024.
- BIP 360 (Pay-to-Merkle-Root, status Draft) proposes a Taproot-like output without the exposed key path. It is not activated.
What you can do now
Avoid address reuse. That alone keeps your public key hidden until you spend.
Bitcoin can upgrade by soft fork, as it did with SegWit and Taproot. The risk is real but distant, and the work started early.