A Third of All Bitcoin Is a Sitting Duck for Quantum. Now Bitcoin Has to Choose.

A future quantum computer could one day crack the addresses holding roughly a third of all Bitcoin, including a fortune widely believed to be Satoshi's. A proposal called BIP-360 offers a safer address, but the harder question is whether to freeze the exposed coins to protect them, or leave them and risk watching them get stolen.

Somewhere on the Bitcoin ledger sits a pile of coins nobody has touched since 2010. Around 1.7 million of them, by analysts' estimates, widely believed to belong to Satoshi Nakamoto, the anonymous person or people who invented Bitcoin and then vanished. At today's prices that hoard is worth a staggering sum, and it just sits there, glittering and frozen in time.

For fifteen years, that was a charming mystery. Now it is a problem, because those coins, and millions more like them, may be quietly counting down to the day a machine can pick their lock.

Here is the uncomfortable arithmetic. Somewhere between 6.5 and 6.9 million bitcoin, by analysts' estimates, call it a third of every coin that will ever exist, sit in addresses that a powerful enough quantum computer could, in theory, one day crack open and drain. Satoshi's stash is part of that number, and so are the coins of anyone who used an old-style address or reused the same one twice. No such computer exists today, not close. But Bitcoin cannot wait for the emergency to arrive, because the fix, whatever it turns out to be, could take years to roll out.

You do not need a physics degree for this part. Every bitcoin address is guarded by public-key cryptography: think of a lock with two keys, a public one you can share freely (your address) and a secret private one that proves the coins are yours. The system is built so that the public key tells you nothing useful about the private one. Working backwards, from the lock to the secret key, would take an ordinary computer longer than the age of the universe.

A big enough quantum computer is a different animal. Running a known method called Shor's algorithm, it could in principle do exactly that backwards trick: start from an exposed public key and calculate the private key that opens it, then move the coins. The catch is the word exposed. Older address types show their public key, and so does any address you have spent from and then reused. Those are the sitting ducks. Crucially, no quantum machine can pull this off yet, so the only real question is when.

For a while the response was calm and technical. On 11 February 2026, a proposal called BIP-360 was published and merged into Bitcoin's official catalogue of improvement proposals. Be precise about what that means: publishing and numbering a BIP makes it an official proposal, not a rule the network has adopted. BIP-360 introduces Bitcoin's first quantum-resistant address type. It works much like Taproot, Bitcoin's modern address standard, with one change that matters enormously: it removes the quantum-vulnerable path, so no exposed public key is left sitting out on the blockchain. Take away the exposed lock, and Shor's algorithm has nothing to grab. By March 2026, a firm called BTQ Technologies had a working version running on a Bitcoin test network.

If the story had stopped there, nobody outside a few forums would have noticed. On 14 April 2026, a companion proposal landed: BIP-361, "Post Quantum Migration and Legacy Signature Sunset." BIP-360 gave people a safe place to move their coins. BIP-361 asks the harder question: what about everyone who does not move, the millions of coins whose owners are asleep, dead, disinterested, or gone, like Satoshi? Its answer is blunt: do not just offer a safe address, force the move, and freeze whatever is left behind. The proposal sketches a phased plan:

This is the choice, and there is no clean way out of it. That is exactly what makes it a story.

Both doors betray something Bitcoin holds sacred. One risks the money, the other risks the meaning. And notice who cannot vote: Satoshi, and the owners of long-lost wallets. A relatively small group of developers, miners and loud online voices would effectively decide the fate of other people's fortunes, some belonging to people who will never even know the debate happened.

It is tempting to file this under "crypto weirdness." Do not. The same public-key math guards bank logins, secure websites, government secrets and every other cryptocurrency. Bitcoin is simply the most visible place the reckoning is playing out in real time, with a named fortune on the line. Others are already moving: in January 2026, Ethereum, the second-biggest crypto network, stood up a dedicated post-quantum security team, and newer blockchains are being built quantum-resistant from day one. Part of what lit the fuse was research in 2025 suggesting the quantum horsepower needed to break this kind of encryption might be lower than experts had assumed, which nudges the danger a little closer than the comfortable "decades away" everyone had leaned on.

Not today, and not for the foreseeable future. No quantum computer that exists comes close to the scale needed to break Bitcoin's cryptography and calculate a private key from an exposed public key. The concern is a future machine, which is why developers are debating defences now: a fix could take years to roll out, so the argument has to happen long before any real threat arrives.

They are two Bitcoin Improvement Proposals, formal numbered documents in Bitcoin's public catalogue. BIP-360 introduces a quantum-resistant address type so newly received coins do not expose a vulnerable public key. BIP-361 goes further, proposing a phased migration that would eventually freeze coins left in old, vulnerable addresses. Crucially, being published as a BIP makes each an official proposal, not an activated network rule, and BIP-361 remains contested and far from agreement.

Under BIP-361 as written, in theory yes. The proposal would eventually switch off the old signature system, and any coins not moved to a quantum-safe address by then could never be spent again. Satoshi's estimated 1.7 million coins would almost certainly qualify, since moving them requires private keys nobody appears to hold. But this is one contested proposal, not a decision, and the community is nowhere near adopting it. None of this is financial advice, it is a live debate, not a settled outcome.

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