Bitcoin Developer Cory Fields Proposes Quantum Landmines to Deter Key Theft

Bitcoin developer Cory Fields has proposed a defensive mechanism dubbed "quantum landmines" to penalize attackers attempting to exploit vulnerable private keys with quantum computers ¹. Outlined in a Nov. 4 post on the Bitcoin development mailing list, the concept introduces game-theoretic traps and auction mechanisms designed to make quantum theft economically unviable rather than mathematically impossible ¹.

Under Fields's thought experiment, a user holding $BTC in an older, quantum-vulnerable address creates a small, quantum-safe output before the arrival of a capable quantum computer ¹. This transaction contains an unrevealed cryptographic proof establishing prior ownership of the legacy key ¹. If a malicious actor later derives the legacy private key via Shor's algorithm, the proposed consensus rules would prohibit an immediate spend; instead, the attacker must post an equal amount of quantum-safe collateral into a time-locked output ¹. During a challenge period, such as 30 days, the original owner can broadcast the concealed receipt to reclaim their original coins alongside the attacker's posted collateral ¹.

Auctions for Abandoned Coins

Because landmines require an active owner to set traps and monitor transactions, Fields also outlined two auction models to address lost or inactive balances ¹. Early network outputs with publicly revealed keys—such as inactive coins mined during Bitcoin's initial years—cannot deploy active defenses ¹. To defend these addresses, Fields proposed "staked auctions" where third parties lock quantum-safe collateral in advance to contest unauthorized transfers, penalizing attackers by destroying the vulnerable assets while distributing a portion of the attacker's collateral to the challenger ¹. A third design, termed a "sats auction," would initiate a public bidding contest without requiring an advance stake ¹.

Fields emphasized that these ideas remain theoretical exercises rather than a finalized software upgrade ¹. Implementing such mechanisms would require the introduction of quantum-safe wallet formats, changes to Bitcoin's consensus rules, and broader developer consensus on network activation ¹. Community efforts have increasingly focused on long-term cryptographic hardening, including previous research into protocol modifications such as Bitcoin Developers Propose BIP 360 to Mitigate Long-Exposure Quantum Vulnerabilities. At the time of writing, $BTC traded at $75,828.