Overview
- The Coinbase Quantum Advisory Council published a report in mid‑June calling for developers to begin building and testing post‑quantum signature systems now rather than waiting for a consensus on policy for vulnerable funds.
- The council estimates roughly 6.7–7 million bitcoin are exposed to future quantum attacks because public keys are visible from legacy address formats and address reuse.
- About 1.7 million BTC sit in early pay‑to‑public‑key (P2PK) addresses whose public keys are already on‑chain and are likely irrecoverable because their owners cannot move them.
- The report refuses to endorse a single governance outcome and lays out three paths for unmigrated coins: a cutoff that would freeze or burn them, leaving them unchanged to preserve property rights, or middle‑ground controls such as rate limits and cryptographic proofs.
- Practical migration tools the council highlights include Hourglass rate limits to cap spendable amounts, BIP‑361 proofs that let owners prove post‑quantum ownership without revealing keys, and PACTs that let users commit to future quantum‑safe addresses; the council also warns proof‑of‑stake validators could be especially at risk.