Ark Invest Report: 35% of Bitcoin Supply Theoretically Vulnerable to Quantum Computing

A new research report examining Bitcoin’s exposure to future quantum computing breakthroughs suggests the risk is real but distant.

In a joint study titled “Bitcoin and Quantum Computing,” published on March 12, 2026, analysts from Ark Invest and Unchained concluded that roughly 35% of the Bitcoin supply could theoretically be vulnerable if powerful quantum machines are eventually developed, but current technology remains far from that capability.

The researchers argue that while the theoretical attack surface exists, the Bitcoin network would likely have years or decades to adapt before quantum computing poses a practical threat.

Nearly 6.9 Million BTC Could Be Theoretically Exposed

The report estimates that about 6.9 million BTC, representing roughly 34.6% of the total supply, sits in address types that could become vulnerable if a cryptographically relevant quantum computer (CRQC) were created.

These coins fall into several categories based on how their cryptographic keys are exposed on-chain.

The largest group involves reused addresses, where public keys have already been revealed during previous transactions. Researchers estimate that roughly 5 million BTC, or about 25% of supply, falls into this category.

Another 1.7 million BTC (around 8.6%) sits in older Pay-to-Public-Key (P2PK) addresses. In these early Bitcoin address formats, the public key is visible directly on the blockchain. This category includes an estimated 1 million BTC believed to belong to Bitcoin’s creator, Satoshi Nakamoto.

The report also highlights about 200,000 BTC (roughly 1%) linked to Taproot (P2TR) addresses that could potentially be migrated in the future because certain key-path transaction mechanics expose public keys during spending.

Quantum Hardware Remains Far From Breaking Bitcoin

Despite these theoretical vulnerabilities, the report stresses that current quantum technology remains far from being capable of breaking Bitcoin’s cryptography.

Bitcoin relies on elliptic curve cryptography (ECC) for securing transactions. To break this system, researchers estimate that a quantum computer would require around 2,330 logical qubits along with billions of quantum operations.

Today’s quantum computers operate within what researchers call the “Noisy Intermediate-Scale Quantum” (NISQ) era. Current systems typically have only around 100 logical qubits, far below the level needed to threaten Bitcoin’s security.

Ark Invest researcher David Puell argues that the development of quantum capabilities will likely occur gradually rather than through a sudden breakthrough sometimes described as “Q-Day.”

If quantum computing progresses through visible milestones, developers would likely have significant time to introduce upgrades to Bitcoin’s security framework.

Quantum Breakthrough Would Impact Entire Internet

Another key point in the report is that Bitcoin would likely not be the first system affected by a major quantum breakthrough.

The same cryptographic algorithms used by Bitcoin are widely deployed across the global internet, banking infrastructure, and digital communication systems. A quantum computer powerful enough to break Bitcoin signatures would likely compromise many existing security protocols across governments and financial institutions.

Such a development would likely trigger a coordinated global transition toward post-quantum cryptography across multiple industries.

Developers Already Exploring Post-Quantum Solutions

According to the report, the Bitcoin ecosystem has already begun exploring ways to mitigate potential future quantum risks.

One possible approach would involve introducing quantum-resistant address formats through a soft fork, allowing users to migrate funds into wallets protected by newer cryptographic algorithms such as ML-DSA or SLH-DSA.

Another development referenced in the research is BIP-360, a proposal known as Pay-to-Merkle-Root (P2MR). This upgrade aims to disable certain key-path spending mechanisms that currently reveal public keys during transactions.

Over time, the community could encourage users to move coins into new address formats that remain secure even against future quantum computers.

Potential Governance Decisions Ahead

One long-term scenario discussed in the report involves how the Bitcoin community might handle coins that remain in vulnerable address formats.

If quantum threats ever became realistic, developers and network participants might need to decide whether to freeze or restrict coins that have not migrated to safer cryptographic formats.

Such decisions would likely require extensive discussion and consensus across the ecosystem.

Long Timeline for Quantum Risk

Ark Invest and Unchained ultimately conclude that quantum computing represents a long-term technological consideration rather than an immediate security threat.

While a portion of Bitcoin’s supply sits in theoretically vulnerable address formats, the gap between current quantum hardware and the capabilities needed to break Bitcoin’s encryption remains substantial.

For now, the report suggests the Bitcoin network has significant time to evolve its cryptographic defenses before quantum computing becomes a practical risk.

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