Coinbase is calling for Bitcoin to begin preparing against the threat of quantum computers that could potentially derive private keys from public keys and compromise vulnerable wallets. The exchange outlined its recommendations in a new post, emphasizing that preparation should start now rather than wait for quantum threats to materialize.
How Bitcoin's Current Security Works
Bitcoin's security relies on two signature methods: ECDSA and Schnorr. These techniques work by having users sign transactions with a private key, which the network verifies against the user's public key. Current computers cannot reverse-engineer a private key from this information, keeping Bitcoin secure.
The Quantum Threat
A sufficiently powerful quantum computer, sometimes called a cryptographically relevant quantum computer, could reverse-engineer private keys from public keys and drain wallets. According to Google researchers, such a machine could exist by 2029.
Coinbase's Proposed Solutions
Coinbase recommends several measures for Bitcoin's quantum defense:
- Flexible signature design: Bitcoin's transaction format should support new post-quantum signature types without rebuilding the entire system, allowing signatures to be added, replaced, or combined over time.
- Staged adoption: Active wallets could begin using quantum-resistant signatures before Bitcoin finalizes rules for older signature types, allowing users to protect their funds earlier without forcing immediate universal adoption.
- Stateful and stateless options: While some post-quantum signatures are smaller and faster, they require wallets to track information. Coinbase suggests supporting both stateful and stateless options to give users safer choices.
- Robust implementations: Coinbase emphasizes the importance of software that works reliably across platforms, verifies signatures consistently, and avoids leaking secret information.
- Multi-party computation compatibility: Post-quantum schemes should work well with MPC systems, which help protect private keys and provide security layers for large organizations.
Timeline and Implementation Challenges
Bitcoin's decentralized design makes implementing changes difficult. As Coinbase noted, consensus changes and ecosystem migrations can take years, which is why preparation should begin well ahead of any quantum computer announcement.
Handling Legacy Wallets and Lost Coins
Coinbase recommends addressing the question of dormant or late-migrating wallets separately to avoid delaying broader protections. The exchange expressed concern about dormant wallets and old address types with exposed public keys that could be vulnerable to quantum attacks. It suggested considering whether users with older wallet formats could migrate their funds to quantum-safe outputs later, though it did not take a position on what should happen to coins in wallets whose keys have been lost.
