Coinbase, which safeguards roughly five percent of all Bitcoin, has published a detailed proposal urging the network to begin a transition to quantum-resistant cryptography. The exchange argues that waiting for a quantum breakthrough could leave billions of dollars exposed, and that the migration must start well before any capable machine appears.
The looming quantum threat
Current Bitcoin transactions rely on elliptic-curve signatures—specifically ECDSA and Schnorr—to verify ownership. These algorithms are safe against today’s classical computers but could be compromised if a quantum device capable of solving the underlying mathematical problems were built. Researchers estimate that such a machine might be realized within the next few years, potentially by 2029. If that occurs, an attacker could reconstruct private keys from publicly visible information and empty vulnerable wallets.
Coinbase’s proposed roadmap
The exchange’s blog post outlines a multi-phase strategy. First, it calls for Bitcoin’s transaction format to be altered so that new signature schemes can be introduced without overhauling the whole protocol. Two ongoing proposals—P2MR (BIP-360) and an updated Taproot version—appear to provide the needed modularity.
Second, Coinbase supports a hybrid approach where active wallets can start using quantum-secure signatures while still accepting the legacy methods. A “one-of-two” arrangement would let a single output be spent with either the traditional key or a post-quantum key, giving users early protection without forcing a network-wide switch.
Technical components of the upgrade
Post-quantum signatures fall into two categories: stateful and stateless. Stateful schemes require wallets to keep a record of used one-time signing keys; a failure to track this state could lead to accidental key reuse and forged signatures. Coinbase recommends that any implementation also offer stateless alternatives, which avoid the bookkeeping burden and reduce operational risk.
Robust software quality is another pillar of the plan. Implementations should produce consistent results across platforms, resist timing attacks, expose clear configuration options, and remain safe even if random number generators misbehave. Such safeguards would limit bugs, hacking vectors, and accidental loss of funds.
For institutions that employ multi-party computation (MPC) to split private keys among several parties, the chosen post-quantum scheme must be compatible. MPC-friendly signatures would allow exchanges, custodians, and large enterprises to retain their existing security architecture while upgrading to quantum resistance.
Addressing dormant and legacy wallets
A significant portion of Bitcoin resides in addresses that have never been spent, often belonging to users who have lost access to their keys. Coinbase separates the technical migration from the policy debate on how to treat these dormant funds. The exchange suggests that the discussion on recovery or de-activation of such outputs should proceed independently, ensuring that it does not stall the broader security work.
If the network eventually phases out ECDSA and Schnorr, Coinbase advises a clear path for owners of older outputs to move their coins into quantum-secure addresses at a later date. The specifics of that process remain open, but the principle is to prevent permanent lock-out for anyone who cannot upgrade in time.
Why it matters
Bitcoin’s value proposition rests on the durability of its cryptographic guarantees. A successful quantum attack would not only erase individual holdings but also undermine confidence in the entire ecosystem. By advocating an early, measured transition, Coinbase aims to preserve the network’s integrity while giving custodians and everyday users the tools they need to stay protected. The proposal also highlights the broader challenge of updating decentralized protocols: consensus changes can span years, making proactive planning essential.
