TL; DR
- Coinbase’s The Quantum Advisory Council says post-quantum migration planning should begin before quantum attacks become practical.
- The report estimates that around 7 million BTC are quantum vulnerable because public keys are exposed through legacy formats or address reuse.
- About 1.7 million BTC are said to be held in legacy Pay-to-Public-Key addresses, including early mined and potentially abandoned coins.
- The Council defines the issue as a long-term management challenge, not an emergency.
Coinbase’s Quantum Advisory Council has warned that Bitcoin and other cryptocurrencies need to start planning for a post-quantum migration long before quantum computers can realistically crack today’s public-key cryptography.
In a June 11 report titled “Post-Quantum Migration and Abandoned Coins,” the panel framed the problem as both a technical migration problem and a governance dilemma. The key question is not just how to move users to quantum-secure addresses, but what the network should do with coins that are never migrated.
The report says that no current quantum computer can crack the cryptography that secures crypto assets today. However, the risk is argued to be strategically important as decentralized ecosystems can take years to coordinate major upgrades, especially when user funds, abandoned wallets and property rights are involved.
Why some bitcoins are more exposed
A Coinbase report estimates that approximately 7 million BTC are currently quantum vulnerable. That figure includes coins in address types where public keys are already visible, as well as coins related to address reuse, where the public key becomes exposed after a transaction is broadcast.
One particularly sensitive category is legacy Pay-to-Public-Key addresses. The report says that around 1.7 million BTC are located in these P2PK addresses, where the public keys are directly visible. That group includes early-mined coins, including coins associated with Bitcoin’s earliest history, as well as assets that may have been lost or abandoned.
The problem is different from a simple software upgrade. Active users can be told to move funds to quantum-secure addresses once the appropriate signature schemes are ready. Abandoned coins, lost wallets and inactive early addresses are more difficult because no one will be available to move them.
Management dilemma
The council outlined several broad paths. One option is a strict deadline for migration, after which vulnerable assets that have not been migrated could be frozen or burned to prevent future quantum theft. That approach prioritizes network security, but raises serious property rights issues.
Another option is to preserve the rights and do nothing, leaving the vulnerable coins untouched. This avoids forced intervention, but could allow future attackers to steal exposed assets if quantum capabilities finally become strong enough.
The report also discusses intermediate ideas. These include limiting the rate of how much can be moved from older addresses in any block-like time interval, sometimes described as an hourglass mechanism, and using no-knowledge proofs like BIP-361 to allow users to prove ownership of old keys without exposing sensitive information.
Planning before a crisis
The council’s practical recommendation is to separate the engineering work from the management struggle. In other words, the industry can start building and testing quantum-secure signatures now while still debating how abandoned or vulnerable coins should be handled later.
This difference is important. Waiting for quantum attacks to be imminent would leave networks trying to coordinate technical upgrades, wallet migrations, exchange support and community management under pressure. An early start gives developers and users more space to test the system and avoid hasty decisions.
For Bitcoin owners, the takeaway is not that coins are suddenly insecure today. It is that long-term digital assets need long-term security planning. The more value there is in crypto networks over the decades, the more important it becomes to plan for crypto transitions before they become emergencies.
Coinbase’s report adds another important voice to that conversation. Debating abandoned coins will not be easy, but the Council’s message is clear: the issue of post-quantum migration is no longer theoretical enough to ignore.
