Bitcoin developer proposes a deposit that quantum thieves could lose

Cory Fields has outlined a Bitcoin thought experiment in which future quantum thieves must risk matching collateral. A prepared owner could recover their coins and take the attacker's deposit. The mechanism is not live.

Fields posted the idea to the Bitcoin development mailing list on 4 November. In his example, moving a vulnerable 1 BTC requires another 1 BTC from a quantum-safe output. A waiting period gives the owner time to reveal proof prepared before the attack and claim both coins.

The awkward part is that honest owners would face the collateral requirement too. Someone whose entire holding sits in an old output could need additional bitcoin to move it. Lost keys also prevent owners from preparing the protection.

Fields explicitly presents thought experiments, leaving implementation for later. They assume quantum-safe outputs and new network rules. For readers, this is a discussion about possible incentives for future security, with substantial unanswered design questions; it is not a wallet feature to switch on today.