Coinbase plans post-quantum Bitcoin custody for any scheme

Sep 24, 2026

Coinbase has begun designing a post-quantum custody system intended to protect about $250 billion in institutional assets while supporting any new signature scheme adopted by Bitcoin or another blockchain.

Coinbase prepares custody for several signature schemes

MARA Foundation TV hosted Coinbase Chief Cryptographer Yehuda Lindell, who said the exchange wants its custody platform to remain usable regardless of which post-quantum signature schemes blockchains eventually select.

Bitcoin has not chosen a signature scheme for practical post-quantum use, leaving custodians without a single technical standard around which to rebuild their systems. Lindell said different blockchain communities may also reach different decisions instead of adopting one common scheme.

Post-quantum signatures challenge existing MPC custody

Many institutional custody platforms use Multi-Party Computation, or MPC, to divide control of a private key among several parties. Under such an arrangement, no participant needs to hold or assemble the full private key while approving a transaction.

Lindell said many post-quantum signature schemes may be “not friendly to MPC” because their mathematical design differs from the signatures now used by major blockchains. Hash-based signatures present a particular problem because they lack the arithmetic structure on which traditional cryptographic key splitting depends.

Hardware modules could provide a custody fallback

To reduce its dependence on MPC compatibility, Coinbase is exploring a backup design built around programmable Hardware Security Modules, according to Lindell.

HSMs are physically protected devices used to store cryptographic material and perform sensitive operations. Under the architecture being considered by Coinbase, private keys would remain encrypted using post-quantum cryptography and would be assembled only inside secure HSMs.

Bitcoin has not approved a quantum migration plan

Bitcoin currently uses elliptic-curve cryptography, and no publicly demonstrated quantum computer can derive its private keys from exposed public keys. Researchers and industry groups have still called for early preparation because changing Bitcoin’s security model would require software development, testing, wallet upgrades, and network consensus.

Crypto.news reported in June that Coinbase’s advisory board urged Bitcoin developers to begin creating migration tools before a cryptographically relevant quantum computer exists. The board estimated that about 1.7 million BTC sit in older pay-to-public-key addresses with exposed public keys, while address reuse could place as many as 5 million BTC within a future risk category.

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