Bitcoin
Nic Carter, co-founder of Castle Island Ventures, has warned that quantum computing could reach a level capable of threatening Bitcoin’s cryptographic security within the next decade, arguing that the network should begin preparing for the possibility before the technology becomes a practical risk.
Speaking on the Coin Stories program hosted by Natalie Brunell, Carter said he was bringing forward his timeline for quantum computing’s potential capabilities. He stressed that the warning does not mean Bitcoin will necessarily be hacked within that period, but that the network’s security architecture may need to evolve before sufficiently powerful quantum computers emerge.
The central concern is Bitcoin’s reliance on cryptographic signature systems to authorize transactions. A sufficiently capable quantum computer could undermine the mathematical assumptions protecting certain exposed public keys, potentially allowing attackers to derive private keys and access vulnerable funds.
For Bitcoin, the challenge is not simply developing a replacement cryptographic system. The network would also need to agree on an upgrade, implement it through its governance and software processes, and give users sufficient time to migrate their holdings to quantum-resistant addresses.
Carter argued that a soft fork could provide a path toward introducing post-quantum digital signatures. However, a transition would require coordination among developers, node operators, wallet providers, exchanges, custodians and individual holders. The technical changes could also introduce trade-offs in transaction efficiency and implementation complexity.
These coordination requirements make the timeline important. Bitcoin cannot eliminate the risk merely by adopting new cryptography in software; users must also move assets into the upgraded security framework. If migration takes years, delaying preparation until a quantum breakthrough is imminent could leave vulnerable holdings exposed during the transition.
The issue is particularly sensitive for older Bitcoin holdings whose owners may be unable or unwilling to move their funds. Carter highlighted the potential vulnerability of long-dormant coins associated with Bitcoin creator Satoshi Nakamoto and early miners, raising a difficult question about what should happen if those assets remain exposed after the network adopts stronger cryptography.
Carter also proposed a controversial approach to the problem of dormant coins. He suggested that a legally authorized recovery process could potentially move vulnerable holdings into a court-supervised fund, allowing verified owners to reclaim their assets. Such a proposal would raise substantial questions about property rights, network consensus and the limits of intervention in a decentralized monetary system. He acknowledged that the Bitcoin community might resist measures that effectively freeze older holdings.
The potential market implications extend beyond the immediate risk of theft. Uncertainty over Bitcoin’s long-term security could influence how investors assess custody arrangements, network resilience and the feasibility of holding the asset over extended periods. If a credible upgrade plan emerges, it could help address those concerns. Conversely, prolonged disagreement over implementation or the treatment of dormant coins could deepen uncertainty about the network’s ability to respond to a major technological challenge.
Carter has not abandoned Bitcoin because of these concerns. He said he had not sold his holdings in response to quantum risk, emphasizing that he wants the network to resolve its security challenges rather than move away from the asset. He also identified multisignature custody using hardware from different manufacturers, exchange-traded funds and professional custody services as options for managing certain custody risks, although these approaches do not eliminate the underlying need for cryptographic resilience.
The threat itself remains dependent on advances in quantum computing, and Carter’s timeline should be understood as a forecast rather than confirmation that a practical attack is imminent. The central question is whether Bitcoin can develop and coordinate a credible transition before quantum capabilities reach the point at which existing cryptographic protections become unreliable.
For markets, the next important developments will be progress toward an agreed post-quantum signature standard, a practical migration framework and a resolution of the debate over older, potentially vulnerable holdings. Those decisions could prove as consequential as the underlying technological advances because Bitcoin’s security depends not only on its cryptography, but also on the network’s ability to coordinate changes without undermining confidence in its rules.
