Bitcoin proposes phased quantum upgrade to safeguard against future attacks

A draft Bitcoin Improvement Proposal, BIP‑361, outlines a multi‑year soft‑fork to transition the network from legacy ECDSA and Schnorr signatures to quantum‑resistant cryptography. Phase A, expected to activate about 160,000 blocks—roughly three years after approval—would block new transfers to addresses using vulnerable signature types while still allowing spending from existing outputs. About two years later, Phase B would tighten verification for legacy signatures and introduce a rescue path to prevent quantum‑enabled theft.

The proposal, co‑authored by Jameson Lopp and five collaborators, notes that as of 1 March 2026 more than 34 % of Bitcoin had exposed public keys on‑chain, making those coins potentially susceptible if sufficiently advanced quantum computers emerge. Implementation depends on a future post‑quantum signature BIP, and the staged approach aims to give wallets, custodians, exchanges and miners ample time to adapt before any quantum risk becomes acute.