Bitcoin Security Faces Quantum Threat With 4M BTC at Risk

The Bitcoin quantum threat is no longer just a future risk. Recent analyses show that the cryptocurrency, once thought to have 20 years of safety against quantum computing, is already facing serious vulnerabilities. About 25% of Bitcoin in circulation, around 4 million BTC, is stored in addresses that could be attacked using quantum computers.

This puts a large portion of inactive Bitcoin at immediate risk if quantum technology advances as expected. The old belief that Bitcoin has decades to prepare is being challenged. Quantum computing is advancing faster than many expected and the threat is already active today. Bitcoin must move to quantum-resistant systems before attackers exploit these vulnerable addresses.

What Does the Bitcoin Quantum Threat Mean?

The Bitcoin quantum threat comes from the fact that powerful quantum computers could break the security that protects Bitcoin wallets. Most Bitcoin addresses rely on elliptic-curve cryptography, which could be cracked by Shor’s algorithm, a quantum technique that can calculate private keys from public keys.

Deloitte’s January 2026 report shows that about 4 million BTC, or 25% of all usable Bitcoin, are stored in these exposed addresses. If attackers had the right quantum hardware, they could empty these wallets almost instantly, risking serious market disruption. This is not just a small technical issue. Bitcoin’s security system would need a complete upgrade to use post-quantum cryptography (PQC), which is much more complicated than a normal software update.

How Immediate Is the Quantum Risk for Bitcoin?

The Bitcoin quantum threat is moving faster than many expected. IBM has introduced a new generation of quantum chips that are on track to reach quantum advantage this year, with early fault-tolerant systems expected by 2029. Even Ethereum co-founder Vitalik Buterin has warned that elliptic-curve cryptography could fail sooner than planned. 

At the 2025 Devconnect conference, he said Ethereum needs to switch to quantum-resistant cryptography within a few years. The warning is clear because if Ethereum cannot wait, Bitcoin cannot assume it has decades of safety. While experts like Adam Back have suggested Bitcoin has 20 to 40 years to prepare, current evidence shows the Bitcoin quantum threat is already affecting the market. Delaying action now is increasingly dangerous.

Why Upgrading Bitcoin Is Not Straightforward?

Transitioning Bitcoin to quantum-resistant protocols is a major technical and operational challenge. Researchers at the University of Kent estimate that a full migration could take between 75 and 300 days, depending on whether the network needs to run at reduced capacity to limit risks. Governance also adds difficulty because Bitcoin’s culture is known for resisting change.

Even the Taproot upgrade, which was a relatively small improvement, took years of debate and coordination. A required migration to quantum-safe cryptography could lead to disagreements, potential chain splits, and long periods of uncertainty. The Bitcoin quantum threat cannot be ignored or delayed. Bitcoin’s past governance experience shows that a rushed or poorly planned upgrade could be just as risky as the threat itself.

What Are the Market Implications of Delayed Action?

The consequences of doing nothing go beyond just technical problems. If attackers take advantage of quantum weaknesses in dormant wallets, millions of BTC could suddenly enter circulation. This sudden surge could cause sharp price drops and shake exchanges and market confidence. Miners with quantum capabilities could also dominate proof-of-work mining, reducing decentralization.

This could turn Bitcoin mining into a concentrated system, putting the network’s core principle of fairness at risk. The Bitcoin quantum threat is not just theoretical. Its ability to disrupt the market is real, making it essential to take proactive steps to protect the long-term stability of the cryptocurrency ecosystem.

Are Post-Quantum Cryptography Measures a Solution?

Using post-quantum cryptography is seen as the only reliable way to defend against quantum attacks. NIST standards provide a framework for upgrading Bitcoin and other networks, but the process is neither simple nor quick. Regulators in Europe are already taking action. The European Commission and member states have introduced a roadmap to protect critical infrastructure with quantum-resistant encryption.

The first migration steps are beginning this year, 2026, with full adoption planned by 2035. Bitcoin and other blockchains that delay action could face serious market and operational problems. The Bitcoin quantum threat requires immediate preparation. Waiting for quantum computers to become fully capable before acting could put a multi-trillion-dollar market at extreme risk.

Conclusion 

The Bitcoin quantum threat is no longer a distant risk. With 25% of Bitcoin supply exposed, quantum computing advancing rapidly, and warnings from industry leaders, taking action is essential. Upgrading Bitcoin to a quantum-resistant system will be challenging in terms of technology, governance, and operations. Still, the cost of doing nothing is far higher than the effort needed to protect the network.

The cryptocurrency industry now faces a crucial choice: act quickly to reduce quantum risks or face potentially severe consequences. The countdown for quantum readiness has already begun. Every year of delay shrinks the margin for safety. Immediate and coordinated action is the only way to keep Bitcoin secure against the next generation of computing threats.

Glossary 

Quantum Computing: A new computing technology that can solve very hard problems fast.

Public Key: A visible Bitcoin code used to receive funds but risky in a quantum era.

Private Key: A secret code that controls access to Bitcoin.

Shor’s Algorithm: A quantum technique that can break today’s cryptographic security.

Post-Quantum Cryptography: Encryption designed to stay secure against quantum computers.

Frequently Asked Questions About Bitcoin Quantum Threat

Why is Bitcoin at risk from quantum computers?

Bitcoin at risk from quantum computers as it uses cryptography that quantum computers may be able to crack.

How much Bitcoin is currently vulnerable?

About 4 million BTC, around 25 percent of supply, is already exposed.

What makes these Bitcoin wallets vulnerable?

These wallets have public keys that could be attacked by quantum algorithms.

Why can’t Bitcoin upgrade quickly?

Bitcoin changes slowly due to technical limits and governance disagreements.

What is the best way to protect Bitcoin from quantum threats?

Bitcoin must move to post-quantum cryptography before attacks happen.

Sources

Cointelegraph

Mexc