Nine crypto companies on Thursday unveiled the Quantum Alliance, an industry group that plans to develop shared security standards for Bitcoin, Ethereum and other blockchain networks as concerns over future quantum attacks move from theory toward long-term planning.
At the center of the debate is a question that has lingered for years: if quantum computers eventually become powerful enough to break the cryptography protecting old wallet formats, who gets control of the bitcoin that could be exposed, including the roughly 1.1 million BTC commonly attributed to Satoshi Nakamoto?
Alliance says 6.4 million BTC already have exposed public keys
The alliance estimates that 6.4 million bitcoin, equal to 30.2% of the supply, already have public keys exposed. It also stressed that those coins cannot be stolen this way today because no existing quantum computer is yet strong enough to carry out that attack.
The concern is that a future machine could work backward from a wallet’s publicly visible key and uncover the corresponding private key, giving an attacker the ability to move funds. Experts cited in the report said wallets holding those coins could become vulnerable if such hardware is built.
Christopher Smith, CEO of quantum-resistant layer-1 blockchain Quantus, said the first party to develop that capability could seize tokens worth billions, potentially with state support.
"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."
No agreement on when the threat becomes real
There is still no industry consensus on when quantum computing will become a practical threat to Bitcoin.
Bryn Bennett, chief revenue officer at The Vault, put it this way: "Nobody knows the date, but the estimates keep falling, and the risk is one we can already plan for. 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 at Postquant Labs, disagreed on the timetable and said 2028 is a realistic date for a machine capable of breaking today’s cryptography.
Recent research has lowered estimates for the amount of computing power needed to attack Bitcoin and Ethereum. Even so, no current machine can break the cryptography those networks use, and forecasts on when one might appear remain contested.
Freeze, move, or place vulnerable coins in a trust
The possibility that at-risk BTC could eventually be stolen has pushed the debate into another difficult area: whether developers should freeze vulnerable assets, including certain bitcoin holdings, before quantum computers can reach them.
Carback said he would rather see those assets moved than frozen. Bennett pointed to a different issue altogether.
"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."
He added: "Any freeze would trade quantum risk for a precedent on property rights and neutrality."
The argument is not new. Binance founder Changpeng Zhao has suggested freezing Satoshi’s estimated 1.1 million bitcoin if the coins remain untouched as quantum technology advances. Bitcoin developer Jameson Lopp has also proposed restrictions on vulnerable coins to prevent future theft. Critics, however, argue that freezing someone’s bitcoin cuts against the core promise that no one can confiscate it.
Quantum resistance would require ecosystem-wide coordination
Making Bitcoin quantum-resistant would require replacing the digital signatures used to authorize transactions. That would demand broad agreement across developers, miners, wallet providers, exchanges and users rather than action by any single group.
"Nobody has a credible single number, and anyone offering one is guessing," Bennett said when asked about costs. "The real cost isn’t the cryptography; it’s coordinating wallets, exchanges, custodians and protocol developers."
Replacement signature schemes could also consume more block space, which could raise fees or reduce the number of transactions Bitcoin can process. Researchers are already working on ways to reduce that effect.
Alliance members plan tests and migration guidance
The Quantum Alliance includes Hacken, Charles Hoskinson’s Midnight Foundation, Quantus and Postquant Labs among its members. The group plans to publish common security tests and guidance for moving existing networks toward quantum-resistant systems.
Carback also floated another option: placing vulnerable coins into a trust, allowing owners who can prove ownership to reclaim their funds.
For bitcoin holders, the unresolved issue is whether the network can protect funds without changing the rules that made the largest cryptocurrency attractive in the first place.