Coinbase has urged the Bitcoin community to begin preparing for the threat posed by quantum computing, warning that moving the network to post-quantum security will be a complex process expected to take several years.
The exchange, which holds 5% of the total Bitcoin supply, said it was already preparing its own systems for a future in which quantum computers could threaten existing cryptographic protections. It argued that the challenge involved more than simply choosing a quantum-resistant signature scheme.
Coinbase said an effective solution should protect both existing vulnerable funds and newly created holdings, operate within Bitcoin’s limited block space and allow full nodes to continue validating transactions independently. It should also be compatible with institutional custody arrangements and everyday wallets, while offering a credible solution for coins that cannot or will not be transferred.
“We believe it is important to begin preparing well ahead of any CRQC (Cryptographically Relevant Quantum Computer) announcement,” Coinbase said. “Bitcoin consensus changes and ecosystem migrations can take years, so it is important that we begin this work now.”
Coinbase sets out design priorities
The exchange said future post-quantum transaction outputs should separate the underlying “container” from the signature scheme. That would allow new systems to be introduced, replaced or combined without requiring a complete redesign.
Coinbase identified P2MR (BIP-360) and P2TRv2 as constructions that appeared to provide the required flexibility.
It also supported a phased approach, allowing active wallets to adopt a post-quantum-capable or hybrid design before a final decision was made on the treatment of legacy signatures.
One model described by Coinbase was a 1-of-2 construction in which the same funds could be spent through either of two routes. One would use a classical ECDSA or Schnorr key, while the other would rely on a post-quantum key.
The company said any support for stateful signature systems should be accompanied by a stateless alternative. It warned that stateful designs could be vulnerable to poor state management, potentially creating a risk of forgery.
For institutional users, Coinbase said compatibility with multiparty computation (MPC) was another significant factor. At least one workable post-quantum option, it added, should show promising compatibility with MPC.
“When implemented effectively, MPC can provide strong protection against key theft, and it is an important layer of defense for large organizations that face constant attacks on their infrastructure,” Coinbase said.
The exchange acknowledged that the future of abandoned or inaccessible coins raised difficult questions and required further discussion. However, it said those debates should take place alongside technical efforts to introduce post-quantum signature support.
“Coinbase believes that Bitcoin will continue to be the most trusted cryptocurrency in a post-quantum world,” the exchange said. “We want to contribute to the community’s efforts and help create the conditions for careful, sustained progress.”
