Inside Coinbase’s $250 Billion Playbook for Post-Quantum Bitcoin Custody
Coinbase is preparing custody systems for a future where quantum computers could threaten Bitcoin and other assets, but the post-quantum signature standard Bitcoin may adopt is still uncertain. Yehuda Lindell said Coinbase wants an adaptable architecture that can support different blockchain outcomes rather than betting on a single signing scheme. A key issue is that Coinbase currently relies heavily on MPC-based custody, where key shares are split among parties so no full private key exists in one place. Some post-quantum schemes, especially hash-based signatures, may be difficult or impossible to use with MPC because they lack the algebraic structure MPC depends on. Researchers are exploring possible fixes, but results are still experimental. If Bitcoin’s final post-quantum design is not MPC-friendly, Coinbase is considering a fallback using programmable HSMs, where encrypted keys are assembled only inside physically secured hardware. Coinbase aims to be ready to support whatever post-quantum approach different networks adopt.
