Coinbase is urging the Bitcoin ecosystem to begin preparing for quantum-resistant security now, warning that changes to the decentralized network, wallets and custody systems could take years. The exchange holds about 5% of all bitcoin for clients including banks, asset managers and hedge funds.
A sufficiently powerful quantum computer could eventually derive private keys from exposed public keys and authorize unauthorized bitcoin transactions. Such a machine does not exist today, but the risk is concentrated in wallet signatures rather than Bitcoin’s mining, hashing or historical blockchain record. An estimated 6. 9 million bitcoin are in wallets with publicly visible key information or reused keys that could be exposed to a future quantum attack.
Coinbase says Bitcoin’s transaction format should be able to support new post-quantum signature systems without requiring a complete redesign. It identified P2MR, described in BIP-360, and P2TRv2 as proposals that could provide room to add, replace or combine signature methods over time while accounting for limited block space, verification requirements and wallet compatibility.
The exchange also supports staged protection for active wallets. One possible transition would give the same funds two spending paths: a traditional ECDSA or Schnorr key and a post-quantum key. That approach could allow users to add protection before Bitcoin settles a final policy for older signature types, without requiring every wallet to migrate simultaneously.
The proposed systems would need to work across ordinary wallets, exchanges, hardware wallets and institutional custody operations. Coinbase said signature schemes should be evaluated for dependable cross-platform verification, resistance to implementation and random-number failures, manageable transaction sizes and compatibility with multiparty computation, which divides signing authority across participants or systems.
The exchange also raised concerns about stateful post-quantum signatures, which require wallets to track signing information and avoid reusing it. Coinbase said a stateless option should remain available if stateful systems are adopted because mistakes in managing signing state could create a forgery risk.
The treatment of dormant, lost or inaccessible funds remains a separate governance and engineering question. Bitcoin includes older outputs with permanently exposed public keys, reused keys, dormant holdings and wallets whose owners may no longer have access. Coinbase has not endorsed one remedy, but said any rescue mechanism would need to resist quantum attacks, including attacks by someone who knows an exposed public key but not the original owner’s secret.
Coinbase’s position follows earlier efforts to convene Bitcoin developers, cryptographers, institutional custodians and hardware-wallet specialists. A workshop held in September examined signature schemes, output types, hardware constraints and ways to protect assets that might not migrate in time, but produced no final protocol choice. The company says technical work on post-quantum support should continue while the Bitcoin community debates rules for funds that migrate late or never move.