Coinbase’s Quantum Advisory Council has released a report examining how cryptocurrency networks and users could transition to post-quantum cryptography and addressing the challenge of “abandoned” coins that cannot be upgraded. The publication highlights growing industry attention to quantum computing risks and the need for coordinated planning across protocols, wallets, and custodians.
Why post-quantum migration matters
Quantum computing poses a long-term threat to widely used public-key cryptography, including the digital signature schemes that secure most blockchain transactions. While practical, large-scale quantum attacks are not considered imminent, security planning typically assumes long lead times due to the complexity of upgrading cryptographic primitives across decentralized networks.
Regulators and standards bodies have been advancing post-quantum cryptography (PQC), with new algorithms progressing through standardization. For public blockchains, migration entails technical upgrades, broad ecosystem coordination, and user actions to move funds to quantum-resistant addresses once available.
Key issues in post-quantum migration
- Hybrid strategies: Transitional approaches may pair existing signature schemes with PQC to reduce risk while minimizing disruption.
- Wallet and address upgrades: New address types and wallet workflows are needed to enable users to rotate keys and move assets to quantum-safe formats.
- Ecosystem coordination: Exchanges, custodians, wallets, and protocol developers must align on timelines, standards, and user communications.
- Measurement and monitoring: Networks benefit from understanding how much value is potentially at risk (for example, assets tied to exposed public keys or legacy scripts).
- User education: Clear guidance will be required to help asset holders execute safe migrations and avoid phishing or operational errors.
Abandoned coins and governance challenges
The report addresses “abandoned” coins—assets in addresses whose owners are unable or unlikely to sign new transactions, such as wallets with lost keys or long-dormant accounts. These holdings present a specific problem in a post-quantum transition: if private keys cannot be used to move funds, those assets may remain on legacy cryptography indefinitely, potentially increasing their exposure to future quantum attacks.
Possible responses raise technical and governance questions. Options discussed across the industry range from leaving such coins untouched to exploring protocol-level mechanisms that could enable safer rekeying under defined conditions—approaches that would require broad consensus and careful consideration of decentralization and property rights.
Outlook
The Coinbase council’s publication underscores the importance of early planning for post-quantum security, even as timelines for practical quantum threats remain uncertain. Concrete next steps for the ecosystem include progressing wallet and protocol designs that support PQC, advancing standards, and preparing user-focused migration pathways that prioritize safety and interoperability.