Moving old-generation Bitcoin with 1:1 collateral... Fields proposes quantum defense

Bitcoin Core developer Cory Fields has proposed a quantum-defense scheme in which anyone moving an old bitcoin (BTC) output must post an equal amount of BTC as collateral, so that if a quantum attacker steals the coin, the original owner can reveal a pre-committed proof and claim both the coin and the attacker’s collateral. Fields posted the idea to the Bitcoin developers’ mailing list on November 5, framing it explicitly as a thought experiment rather than a finalized security feature or consensus rule. The proposal matters because early P2PK outputs expose public keys on-chain and are seen as the most quantum-exposed coins, and the mechanism would require quantum-safe transaction outputs to exist before a real attack, with old-output spends carrying the collateral requirement. What to watch next is whether the concept gains traction among developers and how it might interact with other proposed quantum-resistance approaches for Bitcoin.