How Quantum Computing May Disrupt Cryptocurrency Security, and why you should stay away from crypto. | by Adil Siddiqui | The Capital | Mar, 2025

Cryptocurrencies have revolutionized finance by leveraging cryptographic principles thought to be unbreakable by conventional computing methods. However, the emergence of quantum computing technology represents a paradigm shift that could fundamentally challenge the security foundations of digital currencies. This article explores how quantum computers specifically — rather than traditional supercomputers — pose an existential threat to cryptocurrency as we know it.

Today’s cryptocurrencies primarily rely on two cryptographic principles: hash functions and public-key cryptography. While hash functions may remain relatively secure against quantum attacks, public-key cryptography — the backbone of cryptocurrency wallet security and transaction validation — is particularly vulnerable to quantum computing methods.

At the heart of quantum computing’s threat to cryptocurrency lies Shor’s algorithm, developed by mathematician Peter Shor in 1994. This quantum algorithm can efficiently factorize large prime numbers — a task that would take conventional computers billions of years. Most cryptocurrencies use the Elliptic Curve Digital Signature Algorithm (ECDSA), which quantum computers running Shor’s algorithm could potentially break in hours or days rather than the billions of years required by classical computers.

Beyond breaking signatures, quantum computers utilizing Grover’s algorithm could dramatically accelerate the mining process through quadratic speedups in search functions. This could enable:

• Rewriting blockchain history through rapid re-mining of blocks
• Centralization of mining power in the hands of quantum computer owners
• Undermining of proof-of-work consensus mechanisms

Experts disagree on precisely when quantum computers will reach the capability to break cryptocurrency encryption. Current estimates suggest:

• 5–10 years until early quantum computers might theoretically threaten some cryptographic systems
• 10–20 years until more practical quantum attacks become viable
• Varying vulnerability timelines based on the specific cryptocurrency and its cryptographic implementations

The cryptocurrency community hasn’t been passive in the face of quantum threats. Several adaptation strategies are being developed:

Researchers are developing quantum-resistant algorithms that could replace vulnerable cryptographic methods. Projects like NIST’s Post-Quantum Cryptography Standardization are evaluating candidate algorithms that resist quantum attacks.

Some blockchain projects are exploring quantum key distribution (QKD), which uses quantum mechanics principles to secure communications in ways that detect potential eavesdropping attempts.

Many cryptocurrency projects are implementing hybrid classical-quantum resistant approaches to maintain backward compatibility while introducing quantum resistance.

Several forward-thinking cryptocurrency projects are already implementing quantum-resistant features:

• Quantum Resistant Ledger (QRL), built from the ground up with post-quantum cryptography
• IOTA, transitioning to quantum-resistant signatures
• Ethereum, considering quantum resistance in its roadmap
• Bitcoin, with various proposals for quantum-resistant upgrades

While traditional supercomputers pose limited threats to cryptocurrency security, quantum computing represents a fundamentally different challenge. The race between quantum computing development and quantum-resistant cryptography will likely define the future of cryptocurrency security. Projects that adapt early to quantum threats may survive the coming quantum revolution, while those that fail to evolve could become obsolete once practical quantum computers capable of running Shor’s algorithm emerge.

The cryptocurrency industry now faces a watershed moment: embrace quantum-resistant technologies today or risk obsolescence tomorrow. The quantum threat isn’t merely theoretical — it’s an approaching reality that demands proactive solutions from the entire blockchain ecosystem.