Coinbase says Bitcoin faces no imminent quantum break, but argues a signature migration could take as long as seven years, so preparation should start early. The harder issue is governance: what to do with roughly 1.7 million BTC in exposed legacy addresses that may never migrate.
Coinbase says the most advanced quantum machines have fewer than 1,000 qubits, far short of what it takes to break Bitcoin's elliptic-curve cryptography. Yet the company estimates that changing Bitcoin's signature system could take as long as seven years to implement.
Coinbase argues that preparation must begin beforehand, because the transition would involve developers, custodians, wallet providers, hardware-wallet makers and institutions rather than a single software activation.
A seven-year window sets the pace for action
Because the implementation itself may consume much of the time before any threat arrives, Coinbase Institutional Research places a possible signature migration on a timetable of up to seven years. A network-wide move would need software support, planning by companies that hold bitcoin for clients, and action by users who hold their own keys.
Independent research points the same way. A 2026 paper estimates roughly a one-in-six chance that a cryptographically relevant quantum computer exists by 2035, rising to about 60% by 2050. The article describes these as scenario estimates, not a schedule, and the paper concludes that governance could be the binding constraint.
Legacy coins turn a cryptographic fix into a governance fight
Coinbase's Quantum Advisory Council estimates that roughly 1.7 million BTC sit in legacy pay-to-public-key (P2PK) addresses with fully exposed public keys. Owners who can still act could move the coins to a safer output type. Some coins may belong to owners who are lost, inactive or unwilling to migrate.
The council leaves open whether permanently unmigrated coins should be burned, preserved or handled through another governance mechanism. BIP-361 identifies a redistribution conflict if quantum recovery reaches abandoned or exposed coins, with possible approaches that include letting the first capable actor take them, throttling recovery or preventing it.
BIP-360 and BIP-361 sketch a phased route
Bitcoin has two draft proposals for a phased post-quantum migration, not an adopted consensus rule. BIP-360 would keep the post-quantum public key hidden until spending in a quantum-resistant output design. BIP-361 would first prohibit new payments to vulnerable address types and later retire legacy ECDSA and Schnorr signatures.
Standards already exist: the US National Institute of Standards and Technology finalized ML-KEM, ML-DSA and SLH-DSA in August 2024. They do not choose Bitcoin's output format or settle the fate of old coins, so Bitcoin still has to decide which address types to restrict, when to retire the old signatures and how to treat abandoned balances.
Source: Crypto Daily
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