Coinbase Warns Against Delaying Bitcoin’s Transition to Quantum-Resistant Security

Coinbase is encouraging Bitcoin developers to start preparing for a potential shift to quantum-resistant cryptography, emphasizing the importance of protecting assets held by institutional and retail clients. The exchange reportedly safeguards around 5% of all Bitcoin on behalf of banks, hedge funds, asset managers, and other customers. While quantum computing remains a future concern rather than a confirmed immediate threat, Coinbase believes the network should begin preparing before existing security methods become vulnerable.

Bitcoin transactions use digital signatures to prove that the person spending funds has the authority to do so. The network currently relies on ECDSA and Schnorr signature schemes, which remain secure against the computing technology available today.

However, a sufficiently advanced quantum computer could potentially calculate a private key from an exposed public key. If this becomes practical, attackers could gain unauthorized access to Bitcoin held in vulnerable addresses.

A machine capable of breaking widely used cryptographic systems in this way is known as a cryptographically relevant quantum computer (CRQC). The report cites projections from Google researchers suggesting that such a machine could potentially emerge by 2029.

Preparing for this development will require more than designing new cryptographic algorithms. Bitcoin’s decentralized structure means that major protocol changes depend on coordination across the network. Wallet providers, exchanges, custodians, and other infrastructure operators would also need time to develop, test, and deploy compatible solutions.

Coinbase argues that the preparation process should begin well before a CRQC becomes available. Although there is currently no evidence that quantum computers are breaking Bitcoin’s signatures, a transition to new security standards could take years. Starting early would provide developers with time to evaluate different approaches and prepare the infrastructure needed for a gradual upgrade.

Coinbase Favors Flexible Approaches to Quantum-Resistant Bitcoin

Coinbase wants Bitcoin’s transaction outputs, which establish the conditions under which funds can be spent, to accommodate post-quantum cryptography without requiring repeated redesigns of the transaction system.

A flexible framework could allow developers to introduce new signature methods, replace older schemes, or combine different approaches as cryptographic research advances. Coinbase has highlighted P2MR, associated with BIP-360, and P2TRv2 as potential designs for further evaluation.

The exchange also supports a phased migration rather than forcing all users to change their security arrangements simultaneously. One possible hybrid design would allow funds to be spent using either traditional ECDSA or Schnorr signatures or a post-quantum key.

Such an arrangement could help users adopt quantum-resistant protection before the network completes a broader transition. However, Coinbase has not selected a definitive design or established when existing signature methods should be discontinued.

Stateful signature schemes present another challenge because they require wallets to maintain accurate records of signing-key usage. If these records are lost or incorrectly handled, improper key reuse could potentially enable signature forgery.

To address this concern, Coinbase recommends evaluating stateless alternatives alongside stateful designs. This would provide developers with more choices and reduce dependence on perfectly maintained records.

Software Implementation and Institutional Support Are Essential

The move toward quantum-resistant security will require careful implementation as well as stronger cryptographic algorithms. Coinbase recommends consistent signature verification across platforms, safeguards against timing-based information leaks, clear security settings, and protection against failures in the random-number generators used during signing.

These measures could help prevent a security upgrade from introducing new vulnerabilities into wallets and other Bitcoin infrastructure. Even a cryptographic scheme designed to withstand quantum attacks may become unreliable if its implementation contains weaknesses.

Coinbase also wants post-quantum Bitcoin schemes to support multiparty computation (MPC). This technology distributes key-related operations among multiple participants instead of depending on a single person or device.

MPC compatibility is particularly relevant to exchanges, custodians, and financial institutions that manage substantial Bitcoin holdings. If new cryptographic schemes are practical only for individual wallets, institutional adoption could become more complicated and slow the migration process.

Legacy Bitcoin Could Complicate Future Security Upgrades

A future decision to restrict or retire ECDSA and Schnorr spending could create problems for Bitcoin held in older transaction formats. Some legacy address types have exposed public keys, while certain dormant wallets may belong to owners who have lost their private keys.

Coinbase warns that an attacker with access to a CRQC could potentially target vulnerable holdings before the public becomes aware that the technology can break existing cryptographic protections.

The company has not endorsed a specific approach for handling dormant, quantum-exposed, or potentially lost Bitcoin. Instead, it argues that these questions should be discussed separately so that disagreements over older holdings do not delay security upgrades for users who can migrate to safer formats.

Any proposed recovery or special-handling mechanism for vulnerable coins would also need to account for quantum-related risks.

For now, Coinbase’s priority is to encourage developers to examine flexible transaction formats, assess implementation risks, and ensure that future cryptographic systems work with both individual wallets and institutional infrastructure.

The question of what to do with legacy Bitcoin remains unresolved. Beginning the technical work now could give the network more time to evaluate solutions and coordinate upgrades before quantum computing becomes a demonstrated threat to Bitcoin’s current signature systems.