Overview
- Google research says a sufficiently powerful quantum computer could recover a Bitcoin private key in under nine minutes.
- Experts note no machine can do this today, yet the finding has moved the risk from theory to near-term planning.
- Roughly 6.5–6.9 million BTC are exposed to such attacks, including about 1.7 million in legacy addresses tied to early miners and Satoshi-era wallets.
- Proposals under review include BIP 360 to keep public keys off-chain for new outputs, SPHINCS+ post‑quantum signatures that are far larger, and a commit‑reveal scheme to protect transactions waiting in the mempool.
- None of the measures are activated, and debate is growing over voluntary upgrades versus restrictions on old wallets such as Hourglass V2 withdrawal limits or ideas to lock Satoshi’s coins, which many insiders say would be unlikely to win consensus.