Bitcoin developer Cory Fields has proposed an innovative defense mechanism against potential quantum attacks on the cryptocurrency. His idea, dubbed "quantum landmines," aims to make stealing Bitcoin through quantum computing a risky and costly endeavor. Fields outlined the concept in a November 4 post to the Bitcoin development mailing list, emphasizing that it remains a theoretical exploration rather than a ready-to-implement upgrade.
The core of Fields's proposal involves creating hidden proofs of ownership for vulnerable Bitcoin wallets. Before a hypothetical "Q-Day", when quantum computers could break current cryptographic protections, wallet owners could set up small, quantum-safe outputs containing evidence of their control over the original private key. If a thief later uses a quantum computer to steal the coins, they would be forced to post collateral, effectively turning the theft into a gamble where they could lose their own Bitcoin.
Fields also suggested two types of auctions to address apparently abandoned coins. The first, a "staked auction," allows users to secretly bid against specific old wallets before Q-Day. If a thief attempts to move those coins, the highest bidder can challenge the theft and claim part of the attacker's collateral. The second, a "sats auction," requires no advance stake but turns the theft into a bidding contest where the highest bidder wins the coins minus their bid, while the runner-up loses their bid.
Implementing these ideas would require significant changes to Bitcoin, including quantum-safe wallets, new consensus rules, and agreement on activation timelines. Fields acknowledged that the trade-offs are severe, as honest owners might need large collateral deposits, and inactive holders could miss their chance to object. Despite these challenges, Fields believes some mechanics could be introduced through a soft fork, though no detailed design or activation schedule has been provided.