BIP-361 UPDATED — LOPP COAUTHORS THE QUANTUM MIGRATION. TWO PHASES, LEGACY SIGNATURE SUNSET, AND 1.1M SATOSHI COINS ON THE LINE.

Jameson Lopp has coauthored Bitcoin’s updated post-quantum migration proposal — BIP-361 — with Christian Papathanasiou, Ian Smith, Joe Ross, Steve Vaile, and Pierre-Luc Dallaire-Demers. The proposal, updated Monday on the BIPs registry, describes a two-phase migration away from Bitcoin’s current ECDSA and Schnorr signature schemes. Phase A would restrict legacy transactions to post-quantum destinations approximately three years after activation. Phase B would tighten legacy spending rules roughly two years later through a quantum-safe recovery process. The proposal is currently classified as draft informational — not activated, does not require Bitcoin holders to move funds. The contested line is the estimated 1.1 million BTC held in inactive wallets, including coins linked to Satoshi Nakamoto, that could be permanently frozen under Phase B if private keys are never used to migrate. Critics have called the proposal authoritarian and confiscatory. Proponents describe it as security migration with sunset windows measured in years. Two design goals sit in tension: preventing future protocol-level theft by quantum attackers, and preserving the immutability of long-term holdings whose owners may never come back online. BIP-361 is where the tension gets formalized.