How Could a Quantum Upgrade Expose Dormant Bitcoin?
Blockstream CEO Adam Back said a future post-quantum migration of Bitcoin could provide new insight into how much of Satoshi Nakamoto’s holdings remain accessible. The process would require users to move funds from older, potentially vulnerable address formats into quantum-resistant ones, effectively forcing activity across legacy wallets.
Speaking at Paris Blockchain Week, Back said coins that remain unmoved after such a transition could reasonably be considered lost. The logic is straightforward: any holder seeking to protect funds from future quantum threats would need to actively migrate them.
“This migration to post-quantum address format may tell us how many of those coins [Satoshi] still has,” said Back, adding that the pseudonymous creator is estimated to control between 500,000 and 1 million Bitcoin.
Blockchain analytics firm Arkham estimates that wallets linked to Nakamoto hold around 1.09 million Bitcoin, currently valued at more than $80 billion. These holdings have long been a source of debate, particularly as concerns around quantum computing risks begin to enter mainstream discussion.
Why Is Quantum Risk Back in Focus Now?
The discussion follows a new Bitcoin Improvement Proposal published by Jameson Lopp and five co-authors, which seeks to restrict the future movement of coins held in quantum-vulnerable address formats. The proposal targets older wallets where public keys have already been exposed, making them more susceptible to potential cryptographic attacks.
While the risk remains theoretical, the proposal highlights growing attention within the developer community toward long-term security assumptions. Bitcoin’s current cryptographic framework relies on elliptic-curve signatures, which could be broken if sufficiently powerful quantum computers are developed.
The debate is not about immediate risk but about preparing for a structural change in the security model. A coordinated migration would require both technical upgrades and broad user participation, making early planning critical.
Investor Takeaway
How Much Time Does the Market Have to Prepare?
Back downplayed the immediacy of the threat, arguing that a quantum breakthrough capable of compromising Bitcoin signatures is likely decades away. He estimated that such capabilities are at least 20 years from becoming practical.
He described current quantum systems as “less powerful than a $5 calculator,” noting that scaling challenges, including energy consumption, remain significant barriers. This timeline, if accurate, gives developers and users a long runway to design and implement a transition.
The extended horizon also reduces near-term market pressure, allowing upgrades to be introduced gradually rather than under crisis conditions. However, it does not remove the need for coordination, as any transition would require network-wide consensus.
What Would a Post-Quantum Bitcoin Look Like?
Blockstream Research has already outlined a potential path forward. In December 2025, the firm published a paper proposing a hash-based signature scheme as a replacement for current cryptographic methods, including ECDSA and Schnorr signatures.
Unlike elliptic-curve systems, hash-based signatures rely on the security of hash functions, which are widely considered resistant to quantum attacks. The proposal suggests that such schemes could be integrated into Bitcoin as a long-term safeguard.
Any transition would likely involve a phased approach, allowing users to migrate funds over time while maintaining backward compatibility. The process would also require updates across wallets, exchanges, and infrastructure providers.
The outcome would extend beyond security. A large-scale migration could reshape perceptions of Bitcoin’s circulating supply, particularly if a portion of early coins remains untouched. That dynamic could influence long-term valuation models and market narratives around scarcity.