Coinbase says Bitcoin (BTC) should start preparing well before anyone announces a quantum computer capable of breaking its cryptography. The exchange set out its technical considerations in an October 13 blog post.
Coinbase holds roughly 5% of all BTC, worth more than $80 billion at current prices. It said the post aims to inform community debate and does not set a final company position.
Coinbase’s Wish List for a Post-Quantum Bitcoin
Coinbase said choosing a quantum-resistant signature scheme is only one part of securing Bitcoin. It noted that a comprehensive transition plan would protect exposed and new funds while fitting Bitcoin’s limited block space.
The plan would also keep full nodes able to validate the chain on modest hardware. It would need to suit custodians and everyday wallets alike, and give unmoved coins a workable migration route.
“We believe it is important to begin preparing well ahead of any CRQC announcement. Bitcoin consensus changes and ecosystem migrations can take years, So it is important that we begin this work now,” the blog read.
Coinbase’s key considerations cover five areas:
- A flexible output type, such as P2MR (BIP-360) or P2TRv2, that can introduce, replace, or combine signature schemes without a complete redesign.
- Staged protection, allowing active wallets to adopt post-quantum or hybrid setups before the final policy on legacy signatures is settled. One option is a 1-of-2 design that allows funds to be spent through either a classical or a post-quantum key.
- A stateless option alongside any stateful scheme, since errors in state management can potentially enable forgery.
- Reliable implementations, with deterministic verification across platforms, constant-time code, clear parameterization, and protection against signing random-number-generation failures.
- Compatibility with multiparty computation (MPC), which can help large organizations protect keys against theft.
Old Coins With a $575 Billion Price Tag
Coinbase’s quantum advisory board estimated in April that about 6.9 million BTC sit in addresses with exposed public keys. At $83,307 per coin, those holdings are worth roughly $575 billion.
The new post argues that legacy funds need their own governance and engineering track, running alongside the signature work. It names pay-to-public-key outputs, reused keys, lost keys, and Satoshi-era holdings among them.
Coinbase also suggests weighing whether late movers could still migrate if Bitcoin later limits or ends current signature types.
The Quantum Doubt Weighing on Institutional Money
Coinbase said its considerations draw on its own work and on needs it hears from institutional customers. Two prominent market voices have tied their Bitcoin calls to the same quantum risk.
Kevin O’Leary said in September that Bitcoin can reach $1 million, but only if quantum doubts get resolved. He also said in February that institutions would cap Bitcoin allocations at 3% until then.
Jefferies strategist Christopher Wood dropped a 10% Bitcoin position from his model portfolio over quantum concerns.
ut what would happen to the price if a code-breaking quantum computer appeared? Swiss custody firm Taurus expects the price to take the first hit. Its June report said prices would collapse once the machine became known, before any theft took place.
Coinbase lists covert theft, before the public learns such a machine exists, among the risks to weigh for legacy coins. In either case, quantum risk remains a major consideration for investors.
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