Nine crypto companies have launched the Quantum Alliance, a coordinated effort to prepare bitcoin, Ethereum and other blockchain networks for potential quantum computing attacks. The group's unveiling on Thursday arrives alongside a stark warning: an estimated 6.4 million bitcoin — including roughly 1.1 million coins attributed to Satoshi Nakamoto — sit within reach of a future cryptographically capable quantum computer, even as the industry remains sharply divided over when that threat will materialize and what should be done with the exposed coins.

Who controls Satoshi Nakamoto's 1.1 million bitcoin, along with millions of other coins that could be at risk if quantum computers become powerful enough to break the cryptography protecting them, has been a topic of intense debate for quite some time. Christopher Smith, CEO of quantum-resistant layer-1 blockchain Quantus, believes that whoever develops such a machine first could take those tokens — worth billions of dollars — potentially with government backing.

"The most likely scenario is that whoever gets the first CRQC (Cryptographically Relevant Quantum Computer) will take them, probably with the blessing of whichever national government," Smith told CoinDesk. "Hopefully it's a government that likes bitcoin."

Smith's warning came as the nine companies unveiled the Quantum Alliance to develop common security standards for bitcoin, Ethereum and other blockchain networks. The concern underlying the effort is that a future quantum computer could reverse-engineer a wallet's publicly visible key to uncover its secret key, allowing attackers to steal funds. Shor's algorithm, described by mathematician Peter Shor in 1994, makes such key derivation possible in principle once a machine is large enough.

According to the Alliance's estimates, 6.4 million bitcoin — 30.2% of the total supply — have public keys that are already exposed. The group clarified, however, that those coins cannot be stolen this way today, because no existing quantum computer is yet powerful enough to carry out such an attack. In bitcoin's earliest transaction format — which includes Satoshi's known holdings — the public key is written directly onto the blockchain, while addresses in use today expose their public key only after coins are spent from them.

When could the threat arrive?

The first question many are asking is when quantum computers will actually pose a threat to bitcoin. Bryn Bennett, chief revenue officer at The Vault, said the precise date matters less than readiness.

"Nobody knows the date, but the estimates keep falling, and the risk is one we can already plan for," Bennett said. "The question for custodians isn't whether the date is 2028 or 2035; it's whether you can migrate in time if it arrives early."

Richard Carback, chief technology officer of Postquant Labs, took a more definite view, saying he believes 2028 is a realistic date for a machine capable of breaking today's cryptography.

Recent research has reduced estimates of the computing power needed to attack bitcoin and Ethereum. Even so, no existing machine can break either network's cryptography, and predictions about when one might arrive remain disputed. On the defensive side, the U.S. National Institute of Standards and Technology finalized its first post-quantum cryptography standards in 2024, giving software makers reference algorithms to migrate toward.

To freeze or not to freeze

The prospect of exposed coins being stolen raises another difficult question: should developers freeze vulnerable assets, such as bitcoin holdings, before quantum computers can reach them?

Carback said he prefers that vulnerable coins be moved rather than frozen. Bennett sees a different entirely.

"Nobody owns that issue, and that's the problem," Bennett told CoinDesk. "A custodian protects its clients' assets, not abandoned ones. Freezing coins is a governance decision for the Bitcoin network, not for the industry."

"Any freeze would trade quantum risk for a precedent on property rights and neutrality," he added.

The debate has been ongoing. Binance founder Changpeng Zhao has suggested freezing Satoshi's estimated 1.1 million bitcoin if the coins remain untouched as technology advances, and bitcoin developer Jameson Lopp has proposed restrictions on vulnerable coins to prevent future theft. Critics counter that freezing someone's bitcoin goes against the promise that no one can confiscate it.

The coordination challenge

Making bitcoin quantum-resistant would mean replacing the digital signatures used to authorize transactions — a change that requires agreement among developers, miners, wallet providers, exchanges and users. Bitcoin has crossed that threshold before: Segregated Witness activated in 2017 and Taproot in 2021, each following years of discussion across the community.

"Nobody has a credible single number, and anyone offering one is guessing," Bennett said of the cost. "The real cost isn't the cryptography; it's coordinating wallets, exchanges, custodians and protocol developers."

The replacement signatures could also take up more space on the blockchain, potentially increasing fees or reducing the number of transactions bitcoin can process. Researchers are already working on ways to limit that impact.

What the alliance plans to do

The Quantum Alliance, whose members include security firm Hacken, Charles Hoskinson's Midnight Foundation, Quantus and Postquant Labs, plans to publish common security tests and guidance for moving existing networks to quantum-resistant systems.

Carback has also proposed placing vulnerable coins in a trust, an arrangement that would allow owners who can prove ownership to recover their funds.

How bitcoin's developers, miners and custodians respond to those standards — and whether proposals to freeze, move or place vulnerable coins in a trust gather wider support — will shape the next phase of the debate. For bitcoin holders, the unresolved question is whether the network can protect their money without changing the rules that made the number one cryptocurrency so appealing in the first place.

This article was originally published by CoinDesk.