Community Trust ScoreVerified
Six million BTC. That’s the figure making the rounds, and it’s hard to look at. Nine crypto organizations have just created the Quantum Alliance to develop post-quantum security standards, precisely because 6.04 million bitcoins already have a public key visible on the blockchain.
Why It Matters
Why it matters: The formation of a Quantum Alliance underscores that quantum risk is moving from theoretical discussion to concrete security planning, which matters for long-term confidence in Bitcoin’s custody and infrastructure. Even if the assets cited are not currently vulnerable, the headline figure can influence how exchanges, custodians, and protocol developers prioritize upgrades, while also testing whether the market distinguishes between future technical risk and immediate threat.
But “visible” does not mean “stealable.” Not now. The distinction matters and is often misunderstood in mainstream media. These bitcoins have a public key that can be observed, making them theoretically vulnerable to a future quantum attack — but with the machines available in October 2026, no one can do anything with those keys. No current computer runs fast enough, or reliably enough, to reverse the elliptic-curve cryptography that protects Bitcoin. The threat remains in the future. A future that may not be far off, but the future nonetheless.
The figure of 6.04 million also deserves a closer look. It does not refer to a uniform category. Some estimates count only transaction outputs where the public key appears directly on the blockchain. Others include reused addresses, older address formats, or bitcoins linked to Taproot. So the scope varies depending on the methodology. What the figure really says is that public keys are visible in several different configurations — not that all these funds face exactly the same level of risk.
How Bitcoin Becomes Vulnerable to Qubits
Bitcoin relies on elliptic-curve signatures to prove that a transaction really comes from the holder of the private key. When you send BTC, you sign with your private key. Others use your public key to verify that the signature is valid. With a classical computer, working backward from the public key to find the private key would take an astronomical amount of time — making it impractical.
An error-corrected quantum machine could use Shor’s algorithm to solve this mathematical problem much faster. That’s what “exposed bitcoins” means: not an active vulnerability today, but a potential long-term vulnerability, conditional on the existence of a sufficiently powerful and stable quantum computer.
A 2026 study by Google put a number on it: a machine with fewer than 500,000 physical qubits could, under certain assumptions, break Bitcoin’s elliptic-curve cryptography in a matter of minutes. That’s a future architecture. Current processors are too small and too unstable. But the study exists, and it is being taken seriously.
Opinions differ considerably on the timeline. The Quantum Alliance cites estimates that put a first practical attack around the end of the 2020s. Two of its contributors have even created a “Quantum Doom Clock” that points to March 2028 as the first possible window. The Alliance itself stresses that this is not a scientific consensus. Other specialists see the 2030s as more likely. The necessary advances in error correction and logical-qubit production remain considerable.
Who Makes Up the Alliance and What It Really Wants to Do
Quantus, American Fortress, Intmax, Keystone, Midnight Foundation, Postquant Labs, Abelian, The Vault and Hacken. Nine organizations from a range of fields: blockchains, hardware wallets, cybersecurity, zero-knowledge proofs and quantum infrastructure. In short, a bit of everything related to crypto security.
The governance model they have chosen is inspired by the Internet Engineering Task Force — the IETF, which has developed open technical standards for the internet for decades. Public evidence, rough consensus, working implementations. And above all, a company’s size or the number of tokens it holds will not give its positions more weight. That’s a deliberate choice to prevent major players from dominating the debate.
Four working groups. Blockchain migration, post-quantum zero-knowledge proof systems, wallet security, and interoperability between networks. Migration is probably the central problem — and the hardest to solve.
The idea of new post-quantum signatures is appealing on paper. They would protect bitcoins transferred to compatible addresses. But they would not automatically move coins from lost wallets, deceased owners, or holders who simply never move their funds. That’s where the problem lies.
The BIP-361 proposal envisions a gradual transition to new signatures, followed by restrictions on the old ones. It raises an uncomfortable question: what should happen to coins that have not migrated? Freezing them might prevent theft — but would also affect bitcoins held legitimately. The Alliance cannot decide that. It cannot impose anything on the Bitcoin network, whose rules change by consensus. Its role is to develop shared tests and comparable migration methods.
The criteria for determining whether a project is truly “quantum-ready” have not yet been published. There are no details on the publication timeline, either.
What the Alliance can do is clarify what “quantum resistance” means — because protection may involve signatures, consensus, cross-network bridges, oracles, or the keys used to issue stablecoins. These are different layers, each posing a distinct problem.
6.04 million BTC. March 2028 as the first possible window, according to the Quantum Doom Clock. Nine organizations. And “quantum-ready” criteria that have not yet been published.
Frequently Asked Questions
How many bitcoins have a public key visible, according to the Quantum Alliance?
The Quantum Alliance estimates that 6.04 million BTC already have a public key visible on the blockchain. That does not mean these funds can be stolen with the computers available today.
When could a quantum attack on Bitcoin take place?
A “Quantum Doom Clock” created by two Alliance contributors identifies March 2028 as the first possible window, but that date is not a scientific consensus. Other specialists believe the 2030s are more likely.
Which organizations are part of the Quantum Alliance?
The Quantum Alliance comprises Quantus, American Fortress, Intmax, Keystone, Midnight Foundation, Postquant Labs, Abelian, The Vault and Hacken, with expertise spanning blockchains, hardware wallets, cybersecurity and quantum infrastructure.
