[Coinbase Develops Post-Quantum Bitcoin Custody, Compatible with Multiple Signature Schemes] According to a report by Jinse Finance, on September 23, Coinbase's Chief Cryptographer Yehuda Lindell stated on the MARA Foundation TV program that the exchange is designing a custody system capable of supporting any post-quantum signature scheme that Bitcoin may adopt in the future. It is currently unclear which post-quantum signature scheme Bitcoin will use in practical applications. Lindell believes it is unlikely that a single signature scheme will be universally adopted, so preparations must be made for different outcomes across various blockchains. Coinbase currently provides custody for approximately $250 billion in assets for institutions like BlackRock. Traditional Multi-Party Computation (MPC) relies on key sharding, but many post-quantum signature schemes may be "unfriendly to MPC." For example, hash-based signatures lack the arithmetic structure required for traditional cryptographic key splitting. Although cryptographers like Dan Boneh are researching related solutions, this research remains highly experimental, and it is uncertain whether a feasible MPC-like solution can be developed for hash-based signatures. To address this, Coinbase is exploring an alternative architecture centered around programmable Hardware Security Modules (HSMs), where private keys will be encrypted using post-quantum cryptography and assembled only within physically secure HSMs. Lindell stated that while the completion timeline is uncertain, once finished, "I will be able to say that I can support any scheme," without worrying about a blockchain adopting a signature scheme that cannot be supported.