Coinbase says the quantum fix should start now, while Bitcoin still has time to prepare for computers that could derive private keys from public ones. Coinbase holds about 5% of all bitcoin for clients including banks, asset managers and hedge funds, according to CoinDesk.

In a new blog post, Coinbase argues that developers should begin work before a cryptographically relevant quantum computer, or CRQC, appears. The source says Google researchers describe such a machine as potentially existing by 2029. Coinbase warns that Bitcoin consensus changes and ecosystem migrations can take years.

Why the Quantum Fix Started Early

Bitcoin transactions rely on digital signatures connecting private and public keys. The source compares a wallet to a mailbox: anyone can use the visible slot, but only its owner holds the key. A wallet uses its private key to sign a transaction, and the network checks that signature against the public key.

Bitcoin uses ECDSA and Schnorr signature methods. The source says current computers cannot reverse-engineer a private key from those signatures or public keys. A sufficiently powerful quantum computer could do so, making exposed wallets vulnerable to theft. The article says that machine does not exist today.

Coinbase says post-quantum cryptography should protect both old and new funds, fit within Bitcoin’s limited data space and allow regular computers to continue running the network. It also says the upgrade must work for individual users as well as large platforms, with a plan for coins that may not move.

Flexible Signatures and Staged Protection

One proposal would separate Bitcoin’s transaction format from its signature method. Coinbase says that flexibility could make it easier to add, replace or combine quantum-resistant signatures without rebuilding the entire system. It points to P2MR, also called BIP-360, and P2TRv2 as proposals that appear to support this approach.

Coinbase also supports staged protection that lets active wallets adopt quantum-resistant or hybrid signatures before Bitcoin finalizes rules for older signature types. One possible setup would allow the same bitcoin to be spent with either a traditional ECDSA or Schnorr key, or a post-quantum key. This could protect funds earlier without requiring everyone to switch at once.

The exchange says developers should consider whether Bitcoin supports stateful signature schemes. Those schemes require wallets to track which one-time signing keys have already been used. Restoring an old backup or failing to save that record could cause key reuse, which the source says may let an attacker forge a signature. Coinbase therefore favors also supporting stateless options that need no such record.

Wallet Recovery Should Not Delay Protection

Coinbase wants reliable implementations that behave consistently across platforms, avoid leaking secret information through timing, use clear settings and remain safe if a signing system’s random-number generator fails. It also says post-quantum methods should work with multiparty computation, or MPC, which can help organizations avoid relying on one person or device to hold a key.

The exchange left open how Bitcoin should handle older wallets if ECDSA and Schnorr spending is eventually restricted or ended. It says users who migrate late may need a way to move funds, while acknowledging that the approach and trade-offs remain unsettled. Coinbase says this discussion can proceed separately from adding post-quantum signatures.

Forgotten coins raise a related question. Some wallets may belong to people who lost their keys, and some older address types have exposed public keys. Coinbase worries an attacker could drain such wallets before the public learns a quantum machine is available. It did not endorse a specific response, but said any rescue method should itself be quantum-safe.

The debate over dormant funds can run alongside the technical upgrade, Coinbase says, so it does not hold up protection for active users. That sequencing leaves developers with immediate work on signature flexibility and staged adoption while the treatment of coins that never migrate remains unresolved.

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