Bitcoin Core developer Cory Fields has introduced a conceptual defense called quantum landmines aimed at discouraging future quantum-computer theft from vulnerable Bitcoin wallets. The proposal, posted on the Bitcoin Development Mailing List on November 4, would require anyone attempting to spend coins from a wallet whose public key is exposed to first post collateral equal to the amount being moved from a quantum-safe wallet.
Under the example Fields described, a would-be thief targeting 1 BTC would need to provide another 1 BTC as collateral. Both amounts would enter a restricted output with a waiting period, potentially around 30 days. Legitimate owners who had prepared a hidden ownership commitment in advance could reveal that proof during the waiting period, recover their original coins, and also claim the attacker’s collateral. Fields wrote that the attacker would not know in advance whether a wallet was protected, creating an incentive to avoid theft.
The proposal also addresses dormant or lost wallets, including coins from Bitcoin’s earliest years, where original owners may no longer hold keys. Fields outlined an auction mechanism in which participants could place hidden bids against vulnerable holdings. If a quantum attacker later tried to move those coins, an auction would trigger and the vulnerable coins could be destroyed, with the attacker’s collateral distributed among bidders, miners, or other designated recipients.
Fields stressed that the concept remains a thought experiment and would require quantum-safe Bitcoin outputs and new consensus rules, with any eventual implementation likely requiring a soft fork. It could also burden legitimate holders, since moving 1 BTC from an older vulnerable wallet would require an additional 1 BTC in a quantum-safe output. About 7.1 million BTC, roughly 35% of supply, sits in wallets with exposed public keys, according to the discussion. No such mechanism currently operates on Bitcoin, and implementation details including collateral ratios, auction deadlines, and penalties remain unresolved.
The discussion follows broader industry warnings. Coinbase urged developers in October to prepare for quantum threats, while Fireblocks research identified exposed public keys as a major concern and a separate BitMEX proposal suggested restricting older wallets only after evidence of a successful quantum attack.
