TLDR
- Bitcoin Core developer Cory Fields proposed “quantum landmines” on the bitcoin-dev mailing list on November 4.
- A would-be quantum thief would need to post matching collateral before moving vulnerable coins.
- Owners could reveal hidden proof of ownership, reclaim their coins and take the thief’s collateral.
- About 7.1 million BTC, or roughly 35% of supply, sits in wallets with exposed public keys.
- Fields calls the plan a thought experiment, and the rules needed to enforce it are not written.
Cory Fields, a Bitcoin Core developer, posted a new idea to the bitcoin-dev mailing list on Wednesday, November 4, 2026. He calls it “quantum landmines.” The plan would make anyone who tries to steal coins with a quantum computer risk their own money first.
Fields works at MIT’s Digital Currency Initiative. He described the idea as a thought experiment. It depends on quantum-safe wallets and enforcement rules that do not exist yet.
The Quantum Threat to Exposed Keys
Bitcoin uses public-key cryptography. A public key can be seen by anyone, while a private key proves who owns the coins. Developers have long worried that a strong enough quantum computer could work out a private key from an exposed public key.
Some early bitcoin payments showed their public keys from the start. Coins linked to Satoshi Nakamoto are among the possible targets. As of early November 2026, about 7.1 million BTC sat in wallets with exposed public keys.
How the Landmines Would Work
Before quantum attacks become possible, an owner could create a separate quantum-safe output called a landmine. It would hold hidden proof that the owner controls certain coins. The setup follows a commit and reveal style, where a person locks in a commitment first and shows the details later.
Under Fields’ example, a thief who wants to steal 1 BTC would have to add another 1 BTC from a quantum-safe wallet. Both amounts would be locked for a waiting period, such as 30 days. The thief could not tell which coins were guarded by a trap before putting up the money.
During the waiting period, the real owner could see the transaction. The owner could then spend the locked coins to a key committed in advance and reveal the proof. This would return the owner’s coins and hand over the thief’s collateral as a penalty.
Fields wrote that Alice, his example owner, would “notice the transaction in the meantime” and move her coins while taking the attacker’s collateral. He said the thief would have to wait 30 days because the thief has no earlier proof of knowledge of Alice’s key.
The design gives owners a reason to set traps before quantum computers arrive. It also means attackers may avoid stealing coins that could be secretly guarded.
Limits for Lost and Inactive Coins
Landmines only work for owners who still hold their keys. That rules out coins believed lost, including those tied to Satoshi Nakamoto. Fields sketched a separate auction system to protect those coins.
In that plan, rival network participants would place hidden bids on a vulnerable wallet in advance. If a quantum thief attacked, the highest bidder’s contract would trigger. The thief’s target coins would be destroyed, and the thief’s collateral would go to the winning bidder as a bounty.
The setup could also add cost for honest holders. The blockchain cannot tell a quantum thief from a true owner. Someone moving 1 BTC under these rules would need another 1 BTC as collateral.
An early holder with a full fortune in an old wallet would need matching funds to move it. Fields said the rules needed to enforce the ideas are still unwritten.
Soft Fork and Earlier Proposals
Any version of the plan would need a soft fork. That is a backward-compatible change to Bitcoin’s rules. Fields said the soft fork details are unresolved and need further discussion.
Earlier proposals have focused on voluntary migration, where holders move funds to quantum-safe wallets themselves. Others have suggested soft forks to handle at-risk UTXOs, the unspent chunks of bitcoin that make up wallet balances. Some proposals would freeze vulnerable coins, which could also lock out owners who never upgraded.
The landmine idea does not freeze or seize coins. It changes the cost of an attack instead.
As of Thursday, no immediate responses had appeared in the mailing list thread. The next step is feedback from other Bitcoin developers on the post.
