Bitcoin Core Dev Proposes Quantum Landmines to Punish Coin Thieves

Cory Fields, a Bitcoin Core developer at MIT's Digital Currency Initiative, wants quantum thieves to put up their own bitcoin before they can steal anyone else's. He posted the idea, called "quantum landmines," to the bitcoin-dev mailing list on Wednesday, November 4, 2026.

The exposure is large. As of early November 2026, about 7.1 million BTC, roughly 35% of circulating supply, sat in wallets with exposed public keys. A sufficiently powerful quantum computer could work backward from an exposed public key to the private key behind it. Some early bitcoin payments exposed their keys from the start, which puts coins associated with Satoshi Nakamoto among the potential targets.

How the trap works

Fields' example: to steal 1 BTC, an attacker would have to supply another 1 BTC from a quantum-safe wallet. Both coins would be locked for a waiting period, such as 30 days.

Before quantum attacks become possible, the real owner could create a quantum-safe "landmine" holding hidden proof of ownership. If a thief moves the coins, the owner reveals the proof during the waiting period, reclaims the bitcoin and takes the thief's collateral. A thief cannot tell which holdings carry a trap before committing money.

The setup is commit/reveal, like a sealed-bid auction. The commitment comes first, so nobody can see another participant's move and copy or front-run it.

"However, Alice notices the transaction in the meantime and spends the in-limbo output to her committed-to key by including her landmine as an input and revealing the proof. In doing so, she moves her own coins while also taking the attacker's collateral."

Cory Fields

The attacker, Fields wrote, has no such proof. "Because they have no pre-qday proof-of-knowledge of Alice's key, the attacker would have to wait the 30 days before they can re-spend the output."

Lost coins

Landmines only work for owners who still hold their keys. Coins believed lost, including Satoshi Nakamoto's, get no protection.

For those, Fields sketched an auction. Rivals stake hidden bids on a vulnerable wallet in advance. If a quantum thief attacks, the highest bidder's contract triggers: the target coins are destroyed and the thief's collateral goes to the winning bidder.

Limits

The costs are plain. The chain cannot tell a quantum thief from the true owner, so honest holders moving their own vulnerable coins would also need matching collateral. An early holder with a whole fortune in an old wallet would need matching funds.

Fields called the ideas thought experiments. They depend on quantum-safe wallets and enforcement rules nobody has written. Soft-fork mechanics are unresolved, pending further discussion, and any change would need broad community agreement. No immediate responses had appeared in the discussion thread, so whether the mechanism holds up is untested.

Where this fits

Earlier proposals centered on voluntary migration to quantum-safe wallets. Others explored soft forks to manage at-risk UTXOs. A separate dispute asks whether Bitcoin should freeze vulnerable coins or leave them to anyone who can produce a valid signature. A freeze could stop thieves, but it would also lock out owners who never upgraded.

Landmines pull a different lever: an economic penalty on theft rather than a cryptographic upgrade. The open question is whether honest holders can carry the collateral burden.