Coinbase Calls for Quantum‑Safe Bitcoin Upgrade

Coinbase says that as quantum computers grow powerful, the cryptographic scheme that protects Bitcoin could be broken, exposing the 5 % of the network’s total holdings that the company safeguards and the roughly 1.7 million bitcoins that sit in the oldest address types. 7 million bitcoins overall are considered vulnerable, and many of those legacy coins have keys that may never be recovered, so the company stresses the urgency of preparing a migration path for funds that cannot be moved.

Design goals for a quantum‑safe Bitcoin include a flexible architecture that keeps the coin‑holding container separate from the signature scheme, a staged transition with a 1‑of‑2 setup that allows spending with either a classical or a post‑quantum key, and compatibility with multi‑party computation techniques that Coinbase uses to protect custodial wallets. The plan also calls for early preparation before a cryptographically relevant quantum computer appears, keeping a stateless signature option, ensuring robust implementations, and providing a migration route for wallets that upgrade late. Coinbase explicitly says that legacy funds are a separate governance problem and that protection should be offered to those already willing to upgrade.

Coinbase’s proposal builds on work already underway. The BIP‑360 draft introduces a Pay‑to‑Merkle‑Root output type, while a StarkWare researcher has sent the first quantum‑resistant Bitcoin transaction on mainnet. The company is also evaluating post‑quantum signature candidates such as ML‑DSA, SLH‑DSA, FN‑DSA, and SHRINCS, and it participates in the Bitcoin Security Consortium, which has pledged $15 million over three years to support security research. A debate over AI‑driven cryptanalysis has also been raised, but Coinbase’s cryptography lead argues there is no evidence such attacks threaten current schemes.