ARK Invest and bitcoin financial services firm Unchained said in a new whitepaper published March 11 that quantum computing does not pose an immediate threat to Bitcoin, even as they argue the network should keep preparing for that possibility. The paper, co-authored by Unchained’s Dhruv Bansal and Tom Honzik and ARK digital assets analyst David Puell, frames the issue as a long-range security and governance challenge rather than a sudden breaking point for the network.
ARK says Bitcoin quantum risk is years away
The paper’s central claim is straightforward: quantum computing is a “long-term risk but not an imminent threat.” According to the authors, today’s systems remain well short of the capability needed to break Bitcoin’s elliptic curve cryptography, and any meaningful breakthrough would almost certainly hit the wider internet, cloud systems, banking infrastructure and government communications before it became a Bitcoin-only crisis.
In the authors’ view, the idea of a single catastrophic “Q-day” is too simplistic. They write that quantum development is more likely to arrive through “a protracted sequence of observable milestones,” giving markets and the Bitcoin ecosystem time to respond. “Today’s quantum systems lack the capabilities required to compromise Bitcoin,” the report said. “Meaningful breakthroughs would disrupt internet security first, triggering coordinated responses well beyond Bitcoin.”
The whitepaper points to the current “NISQ era,” where quantum systems have roughly 100 logical qubits and circuit depths in the hundreds. By contrast, the paper says breaking Bitcoin’s cryptography would require at least 2,330 logical qubits and tens of millions to billions of quantum gates. That gap underpins the report’s conclusion that practical risk to Bitcoin is still some distance away, even if research progress should be watched closely.
That does not mean the exposure is trivial. The report estimates that about 1.7 million BTC sit in vulnerable Pay-to-Public-Key addresses believed to be lost, while another 5.2 million BTC are held in address types the authors describe as vulnerable but still migratable. Together, that amounts to roughly 35% of outstanding supply, though the paper stresses those coins would not all become stealable at once because an attacker would need to break keys individually.
The authors also devote unusual attention to the gap between the first and second successful key breaks. “A plausible alternative is that breaking the first 256-bit ECC public key is a massive effort that cannot be replicated easily until other major capabilities are developed,” they wrote. “A slow, protracted breakage of Bitcoin public keys would mitigate impact on the network to some extent.” That framing matters, because it argues against assumptions that one successful attack would instantly place all exposed coins at risk.
On timing, the paper says views range from those who fear a cryptanalytically relevant quantum computer before 2030 to those who think such machines are decades away. It says projections from companies including Google, IBM and Microsoft, along with agencies such as NIST, cluster around the mid-2030s. ARK and Unchained’s “balanced scenario” assumes 10 to 20 years before Bitcoin enters a phase where a quantum computer could attack its cryptography directly.
Whitepaper maps a gradual path to quantum risk
The paper lays out a five-stage framework, beginning with today’s Stage 0, where quantum computers exist but are not commercially useful, and ending with Stage 4, where elliptic curve keys could be broken faster than Bitcoin’s 10-minute block interval. The stages in between move from commercial applications in chemistry and materials science to attacks on weak or deprecated cryptosystems, and only later to the ability to break Bitcoin keys at scale.
That staging is central to the report’s argument that warning signs would emerge well before Bitcoin faced an existential problem. “An abrupt single point of failure is unlikely,” the authors wrote. They added that “what we call ‘risk’ unfolds similarly to what we call ‘progress’ or ‘advancement’—incremental events that create the conditions for others.” In practice, that means the first serious indicators may show up outside crypto, through attacks on weaker legacy systems or the spread of post-quantum upgrades across mainstream internet infrastructure.
The paper also argues that defenses are already ahead of the threat. It says post-quantum cryptography is “widely deployed” across parts of the internet, citing standards finalized by NIST in 2024 and integrations into OpenSSH, OpenSSL, browsers and content delivery infrastructure. “We are still in Stage 0, NISQ, when quantum computers are essentially useless and CRQCs do not exist, while several promising post-quantum cryptosystems have been invented and deployed across the internet,” the authors wrote.
Bitcoin, though, is a harder case because any shift to post-quantum cryptography would require consensus changes. The paper says proposals such as BIP 360 are a starting point, but no single implementation has emerged as the obvious choice. It also warns against rushing. “Bitcoin moves slowly and may incorporate only a handful of consensus changes over its entire lifetime,” the report said. “Integrating a hastily reviewed PQC implementation that introduces bugs, or that compromises some other aspects of Bitcoin’s functionality, would be a setback and require further fixes.”
That leaves a second debate unresolved: what to do about coins that remain in quantum-vulnerable addresses if the network eventually adds quantum-safe ones. The paper notes that some commentators want those old coins frozen or burned after a notice period, while critics say that would create an unacceptable censorship precedent. The authors say those questions should be treated separately from the narrower issue of adding post-quantum address formats.
For investors, the whitepaper’s practical takeaway is less about imminent danger than monitoring a sequence of technical and governance milestones. In the authors’ telling, the key variables are when the first Bitcoin public key can be broken, how long it takes to break the second, who controls early systems, and whether the Bitcoin community can coordinate around an upgrade before Stage 4 arrives. The report does not claim certainty on any of those points. It argues instead that the threat, if it materializes, is likely to be visible well before it becomes acute.
The paper lands as more crypto firms and researchers are formalizing work on post-quantum security, from Coinbase’s advisory board to Ethereum Foundation efforts and new Bitcoin proposals. ARK and Unchained are not dismissing the risk; they are placing it on a longer timeline and arguing that Bitcoin’s challenge is as much governance and implementation as raw cryptography. For now, according to the report, quantum risk belongs in long-term planning rather than emergency response.
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