Quantum Computing Threatens Crypto Security

A looming threat to the cryptocurrency market isn’t regulation or volatility, but the potential of quantum computers to crack cryptographic standards. This “Q-Day” could jeopardize digital assets, from Bitcoin wallets to Ethereum smart contracts.

BlackRock Issues Stark Warning

BlackRock, the world’s largest asset manager, has flagged quantum computing as a critical risk in its May 2025 Bitcoin ETF filing. They warned that quantum advancements could “undermine the viability” of cryptographic algorithms.

Vulnerable Bitcoin at Risk

Approximately 4 million bitcoin, about 25% of usable BTC, are in addresses with exposed public keys, making them susceptible to quantum attacks. Once a quantum computer breaks the Elliptic Curve Digital Signature Algorithm (ECDSA), these funds could be stolen almost instantly.

Ethereum’s Potential Hard Fork

Ethereum, like Bitcoin, relies on ECDSA. Vitalik Buterin has discussed emergency hard-fork solutions if quantum computers crack Ethereum accounts. This could involve halting the blockchain for an extended period to migrate to a quantum-resistant chain.

“Harvest Now, Decrypt Later” Attacks

Malicious actors are already collecting encrypted data in “Harvest Now, Decrypt Later” attacks. They aim to decrypt financial transactions, private keys, and government secrets once they have access to a cryptographically relevant quantum computer.

“The quantum threat isn’t coming—it’s here. Nation-states are harvesting encrypted data TODAY, betting they’ll decrypt it tomorrow.”

—Jay Gambetta, Vice President of IBM Quantum

A December 2023 Reuters report stated that cybersecurity expert Tilo Kunz told U.S. defense officials that Q-Day could arrive as soon as 2025.

Post-Quantum Cryptography (PQC) as Defense

The defense against this crisis is a shift to Post-Quantum Cryptography (PQC), rebuilding blockchains’ security foundations. Quranium recently launched its QSafe Wallet, quantum-resistant from the ground up, using SLHDSA and ML-KEM algorithms.

Challenges of Upgrading Blockchains

Researchers at the University of Kent estimate that upgrading the Bitcoin network to be quantum-safe could require 75 days of complete downtime, or over 300 days at reduced capacity. According to a recent report, the global average cost of a data breach reached $4.45 million in 2023, highlighting the financial implications of such vulnerabilities. (IBM)

The Quantum Clock is Ticking

Iain Wood of QRL warns that all blockchains aiming for long-term survival will need to be post-quantum secure by 2035. The quantum threat adds a critical layer of due diligence for traders and investors, meaning the long-term value of any digital asset depends on its roadmap for achieving quantum resistance.