Google Says Fewer Qubits Needed to Break Crypto Encryption

New Google research suggests quantum computers may break crypto encryption with far fewer qubits than previously expected.

By Matthew Clarke | Edited by Julia Sakovich Published: , Updated:
Google Says Fewer Qubits Needed to Break Crypto Encryption
Google research highlights growing quantum risks to blockchain cryptography. Photo: Pexels

Google has revealed new research indicating that quantum computers may require significantly fewer resources than previously believed to break the cryptographic systems securing major blockchains. The findings suggest that cryptocurrencies like Bitcoin and Ethereum could be more vulnerable to future quantum attacks than earlier estimates implied.

According to the study, a quantum computer could potentially crack the elliptic curve cryptography used in these networks with fewer than 500,000 physical qubits. This represents roughly a 20-fold reduction compared to prior projections, marking a significant shift in how researchers assess quantum risk timelines.

Faster Attacks Than Expected

The research highlights a concerning scenario in which a sufficiently advanced quantum computer could derive a Bitcoin private key in as little as nine minutes. This creates a narrow but critical window for an “on-spend attack,” where an attacker intercepts a transaction and computes the private key before it is confirmed on the blockchain.

Such an attack would exploit the moment when a public key becomes visible during a transaction. While still theoretical, the reduced resource requirements suggest that these risks may materialize sooner than expected, prompting renewed urgency across the crypto industry.

Ethereum Faces Structural Risks

The study also points to deeper vulnerabilities in Ethereum’s design. Unlike Bitcoin, Ethereum accounts expose public keys permanently after their first transaction, making them susceptible to “at-rest attacks.” These attacks do not require precise timing, allowing attackers to derive private keys over extended periods.

Researchers estimate that the 1,000 largest exposed Ethereum accounts, holding tens of millions of ETH, could theoretically be compromised within days using a sufficiently powerful quantum system. This structural exposure makes Ethereum particularly sensitive to long-term quantum threats.

Industry Response and Urgent Recommendations

In response to these findings, Google is urging the adoption of post-quantum cryptography (PQC) across blockchain networks sooner rather than later. The company has already set a 2029 target for its own transition to quantum-resistant systems, signaling confidence that breakthroughs could arrive within the next decade.

Industry figures, including Ethereum researchers and developers, are already exploring mitigation strategies such as new signature schemes and protocol upgrades. The Ethereum Foundation has outlined a roadmap to prepare the network for quantum resilience, while discussions continue in the Bitcoin community.

A Shortening Timeline for Quantum Disruption

The updated research underscores a growing consensus that the timeline for quantum disruption may be accelerating. While large-scale quantum computers capable of executing these attacks do not yet exist, the rapid pace of innovation is narrowing the gap between theory and reality.

As quantum computing advances, the crypto industry faces increasing pressure to evolve its security foundations. The shift toward quantum-resistant systems may soon become a necessity rather than a precaution, reshaping how blockchains are designed and secured for the future.

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