Google Warns of Quantum Cyber Threat to Crypto by 2029

The cryptocurrency sector is built on decades-old cryptographic techniques, forming a system that is both transparent and secure, underpinned by complex engineering designed to safeguard assets over the long term.

Despite this, emerging breakthroughs suggest that quantum computing is advancing at a faster pace than anticipated, raising concerns about the resilience of the infrastructure that underpins digital assets.

Unlike classical machines, quantum computers can process highly complex mathematical problems at extraordinary speed, potentially enabling them to bypass traditional encryption methods used to secure digital information.

This poses a significant risk to the US$2tn global cryptocurrency market, which depends entirely on cryptographic protections embedded in blockchain networks.

Although quantum computing remains largely in the experimental phase, anxiety within the industry has been steadily increasing.

Shrinking timelines

Research published in March 2026 by Alphabet’s Google indicates that the timeline for quantum computers breaking encryption may be shorter than previously believed.

According to the company, machines capable of compromising current cryptographic standards could emerge as early as 2029, a notable shift from earlier estimates that placed such developments at least a decade away.

To prevent misuse, Google validated its findings in collaboration with the US government, using secure cryptographic methods.

The report adds: “To share this research responsibly, we engaged with the US government and developed a new method to describe these vulnerabilities via a zero-knowledge proof, so they can be verified without providing a roadmap for bad actors.”

Google is now calling on the crypto sector to begin transitioning to quantum-resistant security well ahead of this projected timeline.

It is working alongside major players such as the Ethereum Foundation and Coinbase to strengthen protections for digital assets.

Separate research from Citigroup and others similarly suggests that advances in quantum computing, coupled with developments in AI, are accelerating the window in which cryptocurrencies could become vulnerable to attacks.

Exposing the keys 

At the core of the crypto ecosystem is blockchain technology, a decentralised and transparent ledger that records transactions across distributed networks.

Security is maintained through cryptographic systems that generate public and private keys, effectively functioning as account identifiers and confidential passwords used to verify ownership and approve transactions.

Whenever cryptocurrency is transferred, the public key becomes visible. While conventional computers cannot derive a private key from a public one, sufficiently powerful quantum machines could make this possible.

Such a capability would enable attackers to forge digital signatures and access funds. The risk is particularly acute because blockchain transactions are irreversible, unlike traditional banking payments.

Bitcoin, the most widely used cryptocurrency, is especially exposed. Its 17-year transaction history has left millions of public keys accessible.

Research from 2025 suggests that as much as 50% of the network could be affected by this vulnerability. A large-scale breach, followed by the rapid liquidation of stolen assets, could trigger a significant market collapse.

Upgrading the networks

Despite mounting concerns, many experts believe there is still a window of several years before quantum computers can effectively compromise blockchain security, allowing time for the development and deployment of quantum-resistant solutions.

However, moving too quickly carries its own challenges. The technology underpinning quantum-resistant cryptography is still evolving, and early adoption could introduce inefficiencies.

These next-generation digital signatures require significantly more data storage and bandwidth, which could slow transaction speeds and increase costs – particularly for networks like Bitcoin that operate under strict capacity constraints.

Zach Pandl, Head of Research at Grayscale, says: “There is an engineering challenge ahead, but there are engineering solutions already on the table.”

Implementing upgrades is especially complex in decentralised ecosystems, where no central authority exists. Instead, changes must be agreed upon collectively by network participants.

As it stands, none of the top 20 blockchains have adopted quantum-resistant signature schemes.

Within the Bitcoin community, developers and stakeholders remain divided over both the appropriate solution and the timing of its deployment.

The Ethereum Foundation, which supports the network behind the second-largest cryptocurrency, has set a target of achieving full quantum resilience by 2029.

Meanwhile, the Algorand Foundation is moving more quickly. It released a post-quantum roadmap last month and plans to introduce post-quantum account support later this year.

The foundation oversees the Algorand blockchain, whose native token currently has a market capitalisation of approximately US$780m.

While cryptocurrencies have reshaped the concept of money, the sector now faces a critical race against time to ensure quantum computing does not undermine its foundations.

Ultimately, its future will depend on whether decentralised networks can implement stronger safeguards before quantum technology renders existing ones obsolete.