Bitcoin Core developer Cory Fields has outlined a speculative defense called “quantum landmines” that would force anyone attempting to move Bitcoin from a quantum‑vulnerable address to post collateral equal to the amount being transferred. The concept, detailed in a November 4 proposal on the Bitcoin development mailing list, aims to make future quantum‑based theft financially risky for attackers while giving legitimate owners a chance to recover their funds.

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How the landmine mechanism would work

According to Fields, a transaction that spends a vulnerable output would require an additional input from a quantum‑safe wallet matching the value of the original coins. Both inputs would be locked in a new output subject to spending restrictions, such as a 30‑day waiting period. If the original owner had previously created a hidden ownership commitment, they could reveal it during this window, causing the attacker’s collateral to be transferred to the rightful owner. The attacker would not know in advance whether the target wallet contains such a commitment, creating uncertainty that could deter attempts.

Auction designs for permanently lost wallets

Fields also addressed the problem of dormant wallets whose owners no longer control the private keys. He proposed an auction system where participants submit concealed bids against a vulnerable holding before any attack occurs. Should a quantum attacker try to spend the coins, an auction would start after the ownership‑proof period expires, allowing the highest bidder to claim the attacker’s collateral and potentially destroy the original coins. Variations of the design could direct collateral to miners or other designated parties, but none guarantee recovery for the original owner.

Practical challenges and next steps

The proposal remains theoretical. Implementing it would require new consensus rules, quantum‑safe transaction outputs, and a method for the network to identify vulnerable coins—something Bitcoin cannot currently do automatically. Fields noted that legitimate holders would need to acquire additional Bitcoin in a quantum‑safe wallet to move funds from older addresses, which could create liquidity hurdles. He also emphasized that the ideas are “thought experiments” and that no software changes have been drafted.

The broader Bitcoin community is already discussing quantum resilience. Coinbase recently urged developers to prepare for quantum threats, and research from Fireblocks estimates millions of BTC sit in addresses exposed to future quantum attacks. A separate BitMEX proposal suggested activating restrictions only after evidence of a successful quantum breach. Fields’ landmine concept adds another layer to the ongoing debate about how best to protect the network against a technology that does not yet exist.