Coinbase, the cryptocurrency exchange that says it custodies roughly 5% of all Bitcoin in existence, is pressing Bitcoin's developers to begin preparing for the quantum-computing threat before it is too late, arguing that the work cannot wait for certainty that a danger has actually arrived.

In a blog post published Tuesday, the company laid out a detailed technical wish list for how the network should harden itself, framing the shift to quantum-resistant cryptography as a complex, multi-year undertaking that needs to begin immediately. "Bitcoin consensus changes and ecosystem migrations can take years," Coinbase wrote, warning that waiting for the announcement of a cryptographically relevant quantum computer—the kind capable of breaking Bitcoin's signatures—would leave too little time to respond. The timeline reflects Bitcoin's structure: with no central authority, protocol changes require broad agreement among developers, miners, and node operators, a process that has historically unfolded over years.

The concern centers on how Bitcoin secures wallets. A sufficiently powerful quantum machine could, in theory, derive a private key from an exposed public key and drain the funds—a hypothetical milestone the industry calls "Q-Day." Coinbase's position is that the possibility alone justifies starting the work early. The push aligns with a broader shift across the technology sector: the U.S. National Institute of Standards and Technology finalized its first post-quantum encryption and signature standards in 2024, and organizations in finance and technology have since been assessing how to migrate.

The company stressed that a fix involves far more than picking a new signature scheme. Any transition, it said, would need to protect both existing and newly created coins, fit within Bitcoin's limited block space, keep working for ordinary wallets and institutional custody alike, and offer a migration path for coins that never move.

The post reads less like a mandate than a set of requirements from one of the network's largest stakeholders. Coinbase backed a flexible "container" design—pointing to proposals such as BIP-360—that would let new post-quantum signature systems be swapped in over time without requiring a full redesign of the protocol. Any such proposal would move through Bitcoin's open review process, where developer discussion and testing precede any network-wide adoption. It also floated a staged "1-of-2" construction, letting the same funds be spent with either a classical key or a quantum-safe one during the transition period. The company emphasized that whatever scheme Bitcoin adopts should be compatible with multi-party computation (MPC), the key-splitting technique custodians like Coinbase rely on to guard against theft.

Thornier still is the question of dormant, lost, or exposed coins, including Satoshi-era holdings, which Coinbase said should be treated as a separate governance problem. The company argued that this question should be settled through a governance process of its own, rather than being folded into the broader technical transition. It cautioned that any rescue mechanism must itself be quantum-safe, so an attacker who knows only an exposed public key could not exploit it.

The push builds on Coinbase's steady drumbeat of quantum warnings. The exchange convened a quantum advisory board in January to study the risks and to develop precisely the sort of guidance it offered this week. In July, the company joined a Bitcoin Security Consortium alongside asset manager BlackRock and Strategy, pledging a combined $15 million toward quantum-proofing Bitcoin. Whether Bitcoin's developer community takes up these requirements—and on what timeline—remains an open question in a network where no single party can force a change.