Millions of Bitcoins at Risk from Quantum Computers: Developers Weigh In

A significant portion of Bitcoin's circulation is at risk from quantum computers, according to research by Project Eleven and Coinbase. Approximately 7 million BTC are exposed, out of around 14 million addresses scanned with non-zero balances.

The exposure breakdown shows that address reuse is the single biggest culprit, accounting for nearly 4.99 million BTC, or about 72% of the exposed total. Legacy P2PK outputs add another 1.72 million BTC, while Taproot (P2TR) addresses are not fully immune, with around 198,000 BTC at risk due to their x-only public key format.

The debate over how to address this issue has split the Bitcoin developer community, with some advocating for a consensus change, BIP-360, which would introduce a quantum-resistant address format called P2QRH. This approach aims to solve the exposure problem without touching custody assumptions, but it requires broad agreement among miners, node operators, exchanges, and wallet vendors.