Coinbase, custodian of about 5% of all bitcoin, says the quantum fix should start now

Coinbase, which holds roughly 5% of all bitcoin in existence on behalf of clients such as banks, asset managers and hedge funds, has published its view on how Bitcoin should defend itself against a future quantum computer. Its headline message: start preparing now, rather than waiting until the threat is real.

Why quantum computing matters for Bitcoin

Every Bitcoin transaction is authorised with a digital signature created from the owner's private key and checked against the matching public key. Bitcoin uses two signature schemes, ECDSA and Schnorr. Today's computers cannot work backwards from a public key to the private key, which is what keeps coins safe.

A large enough quantum computer could, in theory, do exactly that. No such machine exists yet, but some projections — CoinDesk cites Google researchers — suggest one could arrive around 2029.

What Coinbase is proposing

• Begin the migration early. Moving the network to quantum-resistant signatures will take years of design, review and wallet upgrades, so the work should start before it is urgent.
• Keep the design flexible. According to The Block's reading of the post, Coinbase wants a migration path that can adapt as post-quantum cryptography matures, rather than locking in one scheme too soon.
• Handle lost coins separately. What to do with coins whose owners will never move them — including early, possibly lost wallets — is a contentious question, and Coinbase suggests it should not hold up the technical upgrade.

What it means for holders

Nothing changes for ordinary users today. But the debate is moving from academic papers to the companies that custody large amounts of BTC, and any eventual upgrade will require wallets and exchanges to move funds to new address types.