Inside Coinbase’s $250 Billion Playbook for Post-Quantum Bitcoin Custody

In brief

• Coinbase is developing post-quantum custody safeguards to support a wide range of signature schemes, according to Head of Cryptography Yehuda Lindell.
• Traditional Multi-Party Computation (MPC) relies on split keys, but many post-quantum signature schemes may be “non-MPC-friendly.”
• Coinbase is exploring a fallback architecture that combines post-quantum threshold decryption with programmable Hardware Security Modules (HSMs).

If a cryptographically relevant quantum computer eventually becomes an active threat to Bitcoin's security, Coinbase wants to have protections in place that are prepared for whatever direction Bitcoin and other digital assets take, according to Yehuda Lindell.

In a recent appearance on MARA Foundation TV, the crypto exchange’s head of cryptography told host Isabel Foxen Duke that the company’s post-quantum safeguards are being designed to support any potential forms of technical retooling. At the moment, it is unclear what kind of post-quantum signature scheme Bitcoin will use in practice.

“It’s unlikely that there will be a single signing scheme that everybody will use,” Lindell said in reference to the standards that various networks will ultimately adopt. “That means we have to be prepared and ready for the different outcomes on different blockchains.”