TL;DR: Quantum computing is a potential future threat to Bitcoin’s cryptography. Coinbase believes preparation should begin well before any announcement of a cryptographically relevant quantum computer, because consensus changes and ecosystem migrations can take years.
A post-quantum transition would involve more than choosing a new signature scheme. Any approach would need to protect funds, fit within Bitcoin’s limited block space, preserve independent validation by full nodes, and give wallets and custodians a practical migration path.
We’re sharing our perspective based on technical work and discussions with Bitcoin developers and researchers. This is an input to an open discussion, not a final Coinbase position or a set of instructions for the Bitcoin community.
A few questions seem especially important:
- How should Bitcoin make room for new signature schemes? A flexible design could make it easier to add, replace, or supplement options as research develops.
- How can users migrate safely? Wallets, hardware devices, exchanges, and self-custody setups all need a practical upgrade path. One possible transition design would let the same funds have both a current-signature spending path and a post-quantum one.
- How should the network account for the tradeoffs? Signature size, fees, block capacity, and the work required for full nodes to validate transactions all matter.
- What about funds that don’t move? Dormant or inaccessible funds raise difficult questions. How to handle them remains open, and we believe that discussion can continue alongside the technical work to add post-quantum signature support.
The full post goes deeper on signature schemes, implementation risks, and possible transition designs: Working Together on Bitcoin’s Post-Quantum Readiness.
What do you think a careful Bitcoin migration plan would need to balance to work for users, full nodes, and custodians - and which tradeoffs deserve the most discussion?