Bitcoin Core developer Cory Fields has proposed "quantum landmines," a thought experiment intended to make attempts to steal exposed Bitcoin economically costly. A sufficiently powerful quantum computer could derive a wallet’s secret spending key from its public key, putting coins linked to early payments—including holdings associated with Bitcoin creator Satoshi Nakamoto—among potential targets. Under Fields’ example, stealing 1 BTC would require an attacker to commit another 1 BTC from a quantum-safe wallet, with both amounts locked for a waiting period such as 30 days. Owners who had previously created a separate quantum-safe landmine with hidden proof of ownership could reveal that proof during the lockup, reclaim the targeted coins and take the attacker’s collateral. The attacker would not know which wallets contained traps before committing funds. The proposal applies only to owners who still control their keys, excluding coins believed lost. Fields also sketched an auction system for inactive holdings, in which rivals would post hidden bids through cryptographic traps; an attack could trigger the highest bidder’s contract to destroy the targeted coins and transfer the attacker’s collateral to the winning bidder as a bounty. As of early November 2026, about 7.1 million BTC, or roughly 35% of circulating supply, was held in wallets with exposed public keys, many of them legacy addresses. Fields, who works on Bitcoin software at MIT’s Digital Currency Initiative, posted the proposal to the bitcoin-dev mailing list on Wednesday, November 4, 2026. The idea remains theoretical because quantum-safe wallets, enforcement rules and the required soft-fork mechanics have not been developed, adding an economic-deterrence option to debates over voluntary migration and rules for at-risk UTXOs.