Coinbase has published a detailed list of what it would like to see as Bitcoin prepares for a possible future threat from quantum computers. The blog post, by Coinbase’s Shashank Agrawal and dated 13 October 2026, is the exchange’s own position. Coinbase calls it “an input to an open discussion, not a set of instructions or a final Coinbase position” [1]. No change to Bitcoin has been agreed.
Why quantum computers matter for Bitcoin
Bitcoin uses digital signatures to prove who owns coins. When you spend bitcoin, your wallet signs the transaction with a private key, and everyone can check the signature against your public key. Bitcoin’s current signature schemes, ECDSA and Schnorr, are safe against today’s computers.
A large enough quantum computer could in theory work out a private key from a public key. Experts call such a machine a CRQC, a “cryptographically relevant quantum computer”. None is known to exist, but moving Bitcoin to new “post-quantum” (PQ) signatures would take years of agreement and software changes.
“We believe it is important to begin preparing well ahead of any CRQC announcement,” Coinbase writes [1].
Why Coinbase is weighing in
Coinbase says it is one of the largest crypto custodians in the world and holds “~5% of all BTC in existence”, a figure it gives itself [1]. It says it is preparing its own systems, holding discussions with Bitcoin developers and researchers, and taking part in the Bitcoin Security Consortium [1].
What Coinbase is asking for
A flexible “container”. Coinbase wants a new type of Bitcoin address that can hold different PQ signature schemes, so one can be swapped or added later without starting again. It says “P2MR (BIP-360) and P2TRv2 appear to offer this kind of flexibility” [1]. BIP-360 is a Bitcoin Improvement Proposal; P2MR and P2TRv2 are proposed address types.
A 1-of-2 design for the transition. Coinbase suggests wallets could protect funds before the final rules are settled. In a “1-of-2 construction”, the same coins could be spent in either of two ways: with an ordinary key as today, or with a new quantum-safe key [1]. In plain terms, people keep using their normal key, but a quantum-safe backup route is already in place if it is needed.
A stateless option. Some PQ signature schemes are “stateful”: the signer must keep an exact record of how many times a key has been used, and never reuse a step. Others are “stateless” and need no such record. Stateful ones can be smaller and faster, but Coinbase warns that “state reuse can be catastrophic, leading to immediate forgery” [1]. A person restoring a wallet from an old backup could reuse a step without knowing it. Large exchanges, which sign from many servers at once, would also struggle. “If stateful signatures are supported, we think it is important to also have a stateless option available,” Coinbase says [1].
A wide comparison of schemes. Coinbase wants a Bitcoin-specific evaluation that includes ML-DSA, SLH-DSA, and FN-DSA “when standardized”, and says SHRINCS, a compact hash-based candidate, “is a good fit for this evaluation set” [1].
Support for shared signing. Coinbase and many of its clients use multi-party computation (MPC), where a key is split between several machines. It wants at least one chosen scheme to work well with MPC [1].
Old and lost coins
The hardest question is what to do with coins whose owners have not moved them, including lost coins and very old holdings with exposed public keys. Coinbase says “legacy funds are best treated as a separate governance and engineering problem” and that this debate should not hold up adding PQ signatures [1].
What this means
- It is one voice. This is Coinbase’s view as a large custodian. Bitcoin changes need broad agreement among developers, miners and node operators.
- Nothing has changed yet. BIP-360 and the other ideas are still proposals.
- Big holders want practical options. Coinbase’s main concerns are safe key handling at scale and avoiding fragile stateful designs.
Sources
- Coinbase, Shashank Agrawal, “Working Together on Bitcoin’s Post-Quantum Readiness”, 13 October 2026. https://www.coinbase.com/blog/working-together-on-btc-post-quantum-readiness
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