Cory Fields proposes a quantum landmine scheme, using staked collateral to raise the cost of stealing Bitcoin from old wallets
Bitcoin Core developer Cory Fields posted on the bitcoin-dev mailing list on November 4, 2026, proposing “Quantum Landmines” and a matching auction mechanism, seeking to raise the cost for future quantum attackers to steal Bitcoin from vulnerable old wallets through economic constraints rather than the cryptographic algorithm itself.
Under the proposal, when transferring quantum-vulnerable Bitcoin, the spender would need to provide equal collateral from a quantum-safe output and undergo a waiting period, with 30 days as the example. A lawful holder could present a secret proof of ownership prepared in advance within the period to reclaim the original assets and obtain the attacker’s collateral. Because the blockchain cannot distinguish between an attacker and a lawful holder, the latter would likewise need to provide collateral when transferring such Bitcoin.
Fields also proposed a challengeable auction mechanism for dormant assets whose private keys have already been lost, namely Staked Auction and Sats Auction. He explicitly described these as a “thought experiment,” on the premise that a quantum-safe output type already exists first; the specific soft-fork rules have not yet been written, there is no BIP number, and this is not a network rule that has already been implemented.
Original source:
Title: Bitcoin developer proposes ‘landmines’ to make quantum thieves lose their own BTC Publisher: CoinDesk Publication date: 2026-11-05 URL: https://www.coindesk.com/tech/2026/11/05/bitcoin-developer-proposes-landmines-to-make-quantum-thieves-lose-their-own-btc Source type: media report Verification status: We read the full text key passages, cross-checked the bitcoin-dev original post summary and a BeInCrypto report Supporting content: Fields’s identity, proposal timing, the collateral and waiting-period mechanism, the lawful holder recovery rule, the auction mechanism, and the positioning as a “thought experiment”
ABAB AI Insight
Fields is currently involved in Bitcoin software work at MIT’s Digital Currency Initiative. His proposal does not change the existing cryptography; instead, it assumes that after “Q-day” the network has activated new validation rules and requires all old-output spends to be fully collateralized. This shifts the defensive focus from “preventing quantum computers from breaking private keys” to “making theft after a break economically unprofitable.”
About 7.1 million bitcoins, or about 35% of the circulating supply, are stored in addresses whose public keys have already been exposed, and these are the primary targets for quantum attacks. The proposal requires attackers to first put up equal funds without knowing which addresses contain “landmines”; if holders respond in time, the attackers not only fail to obtain the target coins, but also lose their collateral. This changes the expected payoff of the attack, but does not guarantee that all holders can detect and respond in time.
Lawful holders would also need to prepare additional quantum-safe funds as collateral in order to safely transfer their old coins after Q-day. For holders with early large positions and insufficient extra liquidity, this means migration costs would rise significantly. Fields himself noted that the private keys for many dormant outputs are believed to have been lost, and that landmines alone cannot cover these assets, which is why he introduced an auction mechanism to let third parties bid on the attacker’s collateral.
The proposal is currently still at the mailing-list discussion stage, with no code implementation, no consensus activation path, and no entry into the BIP process. Whether it can be implemented depends on whether the community is willing to introduce new collateral and timelock rules to address a quantum threat that does not yet exist, and to accept that legitimate users will also need to pay additional capital costs during the transition period.
ABAB News · Law of Cognition
Quantum landmines do not prevent private keys from being broken; they only raise the cost of stealing funds after the break.
Lawful holders must also provide equal collateral when moving old coins, and those with insufficient liquidity will face higher costs.
The scheme is a thought experiment, with no BIP, no code, and no activation timetable, and has not yet become a network rule.