Bitcoin faces quantum threat: Over 6 million BTC may be frozen

BIP-361 arrives in April 2026. This isn’t just a casual discussion.

The proposal aims to freeze 6.5 million bitcoins. Why? Because they are vulnerable to quantum attacks. Among these coins, more than a million are believed to belong to Satoshi Nakamoto himself. We’re talking about real addresses, real exposed public keys, real vulnerabilities. What was theoretical two years ago is now a concrete problem. Bitcoin acknowledges control, not ownership on paper. But when someone can break your key with a quantum computer, who really owns your coins?

Not All Bitcoins Are Equal Against Quantum Threats

The quantum risk hits some bitcoins harder than others. A normal address doesn’t reveal its public key until you move your funds. This is crucial. Quantum attackers can’t just extract your private key from an address that lies dormant on the blockchain without first seeing your public key. But the old pay-to-public-key outputs? They expose everything. The old script constructions too. And Taproot, ironically, does the same.

Google Quantum AI published research on March 31, 2026. Bad news for Bitcoin. The secp256k1 curve could fall with less than 500,000 physical qubits. Previous estimates talked about millions of qubits. This reduction changes the game. Current hardware isn’t there yet, true. But algorithmic optimization is progressing faster than hardware. Much faster.

Satoshi’s old addresses use pay-to-public-key. Exposed. The early miners too. Many people who lost their keys had this type of address. It’s estimated that 2 to 3 million bitcoins lie dormant in these vulnerable formats. Add to that the modern Taproot addresses that also expose their public keys by design.

Ownership Doesn’t Disappear Just Like That

Classic property law says something clear. Recovering a private key with a quantum computer is theft. Not a discovery. Not legitimate recovery. Bitcoin enforces technical control, not legal ownership. But the law doesn’t change its rules because a blockchain operates differently.

Ownership isn’t abandoned just because your coins remain unmoved. Abandonment requires a clear intention to renounce. Plus a manifest act. Inactivity alone is never enough. You can leave a house empty for ten years, it still belongs to you. Same for bitcoins.

The Property (Digital Assets etc) Act 2025 in the UK created a distinct category for crypto-tokens. Personal property, but different from tangible goods or contractual rights. This legislation prevents dormancy from being interpreted as automatic abandonment. Other jurisdictions are likely following the same path.

When someone dies, their bitcoins don’t become ownerless. The titles pass to heirs. Or to the state if no one comes forward. Lost keys don’t transfer legal title. Technical inaccessibility isn’t a transfer of ownership. A stranger who acquires your private key via a quantum computer hasn’t discovered an abandoned treasure. They’ve merely obtained the technical ability to move a property that still belongs to someone else.

Financial institutions remain silent for now. No public comments from major banks or funds holding Bitcoin. This lack of reaction could complicate matters later. Because if BIP-361 passes, someone will have to decide who can unlock these coins and when.

Also read: Bitcoin miners sell 32,000 BTC in three months as margins collapse

Dormancy and Legal Complexity

Dormant bitcoins pose a unique problem. Some come from paper wallets forgotten in drawers. Others from poorly labeled backups. Many are linked to storage habits from 2010-2013 when no one really thought about long-term security.

And then there are those who choose not to touch their coins. By strategy. By conviction. By laziness too, sometimes. Impossible to distinguish a lost bitcoin from one simply held without moving.

Property laws require clear intent to prove abandonment. The non-use of a high-value asset proves nothing. This applies to land, inheritances, dormant bank accounts. It applies to bitcoins too. Even if it’s new for courts.

Succession works even when the asset becomes difficult to manage. Legal mechanisms already exist. They adapt slowly to digital assets, but they exist. An heir can claim bitcoins if they prove the deceased owned them, even without having the keys. The problem then becomes technical, not legal.

BIP-361 doesn’t resolve these issues. It raises them. Freezing coins to protect them from quantum threats, fine. But who decides next? Who can unlock them? With what proof of ownership?

Future quantum key holders will have to prove their right. Not just show they can move the coins. This will create complex disputes. Courts will have to decide between technical control and legal ownership. Two concepts that don’t really communicate yet.

Google has reduced the qubit requirements to break secp256k1. This puts pressure on everyone. Holders must review their security. Developers must accelerate on post-quantum solutions. Institutions must stop acting like it’s a problem for 2040.

The market impact could be violent. A successful quantum attack moving dormant bitcoins? Confidence collapses. The price likely follows. Future adoption takes a hit. The economic implications far exceed the 6.5 million BTC involved. Because if these coins fall, all others become suspect.

Precedents are lacking. No court has really ruled on crypto theft by quantum calculation. Because it doesn’t exist yet. But it’s coming. And the legal system will need to react quickly. Too quickly for its usual pace.