Here’s When Quantum Computers Could Threaten Bitcoin’s Security

Capriole Investments founder Charles Edwards has raised fresh alarm over the rising pace of quantum-computing development, warning that Bitcoin’s cryptographic security could be compromised as early as 2027–2029, an event analysts now refer to as “Q-Day.”

The forecast aligns with a growing body of research suggesting that advances in quantum hardware may soon reach the capability required to break elliptic-curve cryptography (ECC), the foundation of Bitcoin’s public-key security.

Multiple Expert Sources Converge on a 2-to-9-Year Risk Window

Edwards’ summary of global findings shows an emerging consensus: Bitcoin’s encryption may be vulnerable within two to nine years, with several independent experts identifying 2027–2029 as a high-probability window.

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  Jameson Lopp (2024): Estimates a 50% probability of quantum decryption within four to nine years.
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  Pierre-Luc Dallaire-Demers (2025): Predicts elliptic-curve cryptography could be breached in two to six years by an operational quantum machine.
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  McKinsey & Co. (2024): Projects Q-Day arriving within two to ten years, assuming RSA 2048 is the first standard to fall, followed shortly by ECC.
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  2017 Bitcoin Quantum Paper (Meta, Microsoft, IonQ collaboration): Found that only 2,330 logical qubits are required to break Bitcoin’s ECC, a threshold that most leading quantum labs expect to surpass within four years.
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  U.S. Department of War (2025): Concluded that cryptographically relevant quantum computers may emerge in as few as three years.

Collectively, these assessments point to a narrowing window of quantum safety — with 2029 identified as the latest plausible upper bound for maintaining current security standards.

What “Q-Day” Means for Bitcoin

“Q-Day” refers to the moment when quantum computers gain the ability to crack cryptographic keys used in existing blockchain networks. In Bitcoin’s case, that means the potential exposure of private keys and wallet signatures, threatening both stored BTC and transaction integrity.

Capriole’s report warns that without proactive migration to quantum-resistant algorithms, the ecosystem faces a systemic security risk. However, researchers also stress that Bitcoin’s open-source nature offers a path to upgrade before quantum decryption becomes viable.

Potential mitigation strategies include:

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  Adoption of post-quantum cryptography (PQC) standards.
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  Gradual rollout of multi-signature and quantum-safe address formats.
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  Coordinated hard-fork planning to ensure network-wide transition once PQC standards stabilize.

Industry Response and Timeline

While most cryptography experts agree that the risk is not immediate, the acceleration of quantum research at Google, IBM, and IonQ suggests the timeline could compress.

Edwards noted that “Bitcoin has four years of very high risk”, citing a 50% likelihood that quantum machines achieve decryption capability by 2029. Still, many developers believe the Bitcoin community can adapt in time, much as it did during previous protocol upgrades.

For now, the message from Capriole is clear: preparation must begin before the breakthrough arrives.