Quantum Alliance warns 6.4 million Bitcoin face future quantum threat

Key points

• The Quantum Alliance estimates 6.4 million Bitcoin, 30.2% of supply, have public keys already exposed, though no existing quantum computer can exploit them.
• Quantus CEO Christopher Smith says whoever builds the first cryptographically relevant quantum computer could seize vulnerable coins, possibly with government backing.
• Postquant Labs CTO Richard Carback calls 2028 a realistic date for a machine able to break today's cryptography, while The Vault's Bryn Bennett says the date is unknown.

Christopher Smith, chief executive of the quantum-resistant layer-1 blockchain Quantus, told CoinDesk that whoever builds the first cryptographically relevant quantum computer could take those coins, probably with the backing of a national government. Researchers disagree on timing: Postquant Labs chief technology officer Richard Carback calls 2028 realistic, while The Vault's chief revenue officer Bryn Bennett says nobody knows the date and that estimates keep falling.

The debate over whether to freeze vulnerable coins remains unresolved. Binance founder Changpeng Zhao has suggested freezing Satoshi Nakamoto's estimated 1.1 million Bitcoin if they stay untouched, and developer Jameson Lopp has proposed restrictions on vulnerable coins.

Making Bitcoin quantum-resistant would mean replacing the digital signatures that authorise transactions, requiring agreement among developers, miners, wallet providers, exchanges and users. Bennett says the real cost is coordinating those groups rather than the cryptography itself.

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