According to CoinMeta, Coinbase is developing an encrypted asset custody architecture for the post-quantum era to adapt to different post-quantum signature schemes that Bitcoin and other blockchains may adopt in the future. Yehuda Lindell, the head of cryptography at Coinbase, stated that it is still uncertain which post-quantum signature mechanism Bitcoin will ultimately adopt. Some schemes, especially those based on hashing, may not be compatible with the existing MPC private key sharding model. For this reason, Coinbase is researching the use of programmable hardware security modules (HSM) as an alternative solution to protect private keys, with private key assembly and signing only taking place within physically protected HSM.