Coinbase Outlines Post-Quantum Migration Framework for Bitcoin

Coinbase released a technical framework on Oct. 14 addressing Bitcoin's long-term vulnerability to cryptographically relevant quantum computers ¹. The crypto custodian, which holds roughly 5% of all circulating $BTC in existence, warned that upgrading the network's cryptographic foundations will require a multiyear effort that must begin well before quantum threats materialize ¹. At the time of writing, Bitcoin traded at $83,504.

The custodian called for separating Bitcoin's transaction container architecture from specific signature algorithms ¹. Coinbase pointed to proposals such as BIP-360 (Pay-to-Merkle-Root, or P2MR) and P2TRv2 as flexible script constructions that could let the network deploy or swap post-quantum algorithms without needing recurring protocol redesigns ¹. Under this model, wallets could adopt staged protections—such as a 1-of-2 spending condition pairing classical ECDSA or Schnorr keys with post-quantum alternatives—ahead of any permanent retirement of legacy signature schemes ¹.

Signature Selection and Custody Constraints

Coinbase highlighted several post-quantum signature schemes for evaluation, including standardized options like ML-DSA and SLH-DSA, impending standards such as FN-DSA, and hash-based constructions like SHRINCS ¹. While stateful signature schemes offer smaller transaction footprints and faster processing, Coinbase cautioned that state synchronization errors can lead to key compromise or signature forgery, making stateless fallbacks essential ¹.

Institutional requirements remain a focal point of the proposal ¹. Coinbase stressed that any chosen post-quantum signature system must support multiparty computation (MPC), hardware security modules, and threshold signing workflows relied on by institutional custodians ¹. The company also noted that developers should establish clear migration frameworks for dormant, lost, or slow-to-move UTXOs without stalling immediate protocol-level signature upgrades ¹.