Analysis of Quantum Vulnerable Bitcoin with Dr. Anthony Milton | Quantum Bitcoin Summit

A recorded talk (presented at Presidio Bitcoin's Quantum Bitcoin Summit, 2025) that breaks down how much of bitcoin's supply is exposed to a quantum attacker. It is the source most often cited for the figure of roughly 6.5 million BTC — about a third of supply — sitting at addresses whose public keys are already visible on-chain.

The talk attributes much of that exposure to address reuse and to large custodial holdings concentrated in reused addresses, rather than to old output types alone. As a conference presentation its figures are estimates tied to a snapshot in time, but it is a useful, specific accounting of the at-risk set.