Bitcoin Core Dev Proposes 'Quantum Landmines' to Make Attackers Pay First

Roughly 7.1 million BTC — about 35% of Bitcoin's circulating supply — sits in wallets with exposed public keys as of early November 2026, and Bitcoin Core developer Cory Fields has proposed a way to make any future quantum attacker risk their own coins before touching that pool.

Fields, who works at MIT's Digital Currency Initiative, posted the concept to the bitcoin-dev mailing list on Wednesday, November 4, 2026. He calls it "quantum landmines" and explicitly labels it a thought experiment. The design depends on quantum-safe wallets and enforcement rules that do not yet exist in any written specification.

The scale of the exposure explains why developers keep returning to the problem. Legacy address formats publish the public key directly on-chain. A sufficiently powerful quantum computer could, in theory, derive the private key from that exposed public key, since Bitcoin's ownership model relies on public-key cryptography where the private key proves control. The count of exposed keys has risen significantly, moving quantum risk from a fringe concern to a recurring topic on developer channels.

How would a quantum landmine work?

Fields' mechanism uses a commit/reveal-style setup, comparable to a sealed-bid auction. A participant locks in a commitment without disclosing details, then reveals them later. Because the commitment comes first, no one can observe another party's move and copy or front-run it.

The "landmine" itself would be a small output created in a quantum-safe format. The output triggers rewards or penalties depending on how someone interacts with it. The practical effect: a would-be quantum thief must post collateral before attempting a theft. Behave honestly and the collateral returns; get caught attempting theft and it could be forfeited.

Fields also describes the framework as a way to protect auctions involving vulnerable coins. He stressed that the soft-fork mechanics remain unresolved. A soft fork is a backward-compatible rule change, the upgrade type Bitcoin has used before to add features without splitting the chain, and it requires broad community agreement. Fields said those details are pending further discussion.

Where does this fit in the broader debate?

The proposal lands in an already crowded field. Earlier proposals centered on voluntary migration, where holders move funds into quantum-safe wallets on their own schedule. Others explored soft forks aimed specifically at managing at-risk UTXOs — the individual chunks of unspent Bitcoin that make up every wallet balance.

Each path carries the same tension. Voluntary migration respects property rights but depends on owners showing up, and some coins belong to people who may never return. Rule changes that restrict vulnerable coins could prove more effective but raise questions about who decides what happens to someone else's Bitcoin.

The landmine idea tries to sidestep part of that fight. Rather than freezing or seizing anything, it changes the economics for the attacker.

What happens next?

For now, the proposal is a mailing list post, not a code change. No responses had appeared in the discussion thread at the time of reporting, so the community has not yet tested whether the mechanism holds up.

Three constraints define its prospects. It reflects a shift from purely cryptographic migration toward an incentive layer — game theory rather than math alone raising the cost of an attack. It depends on quantum-safe wallets being standardized, built and adopted first, which makes it a complement to migration work, not a replacement. And any implementation requires a soft fork, inheriting the political friction of changing Bitcoin's rules.

The 7.1 million BTC figure remains the metric to watch. The next step is developer response on the bitcoin-dev list: if other contributors start identifying flaws or proposing refinements, the thought experiment could begin turning into a specification.