Bitcoin Faces New Risk as Quantum Computing Threat Moves Closer

Quantum computers can solve complex mathematical problems far faster than even the most advanced conventional computers. That capability could allow them to defeat traditional encryption methods used to protect digital information. The risk is particularly significant for the global cryptocurrency market, valued at around $2 trillion, because many blockchain networks still rely on older cryptographic systems to secure digital assets.

Industry concerns have grown since Google published research in March suggesting quantum computers may be able to break existing cryptographic systems earlier than earlier estimates indicated. Google has said encryption-breaking quantum computers could arrive by 2029, compared with previous expectations that such systems were at least a decade away.

Recent research by Citigroup and other institutions has also found that progress in quantum computing and artificial intelligence has narrowed the time frame in which cryptocurrencies could become broadly vulnerable to cyberattacks.

U.S. President Donald Trump last month issued executive orders aimed at strengthening U.S. quantum capabilities and protecting public and private-sector systems from advanced cryptographic attacks. One White House order said large-scale quantum computers could pose a significant threat to widely used cryptographic security systems and warned that adversaries may already be collecting encrypted data to decrypt later.

Some crypto companies and blockchain developers have started drawing up plans to upgrade their networks with quantum-resistant cryptography. Industry officials say the process could take years and may require sweeping changes to the infrastructure supporting digital assets.

Chris Tam, head of quantum innovation at BTQ Technologies, described quantum computing as a direct and existential threat to cryptocurrencies and crypto networks.

BLOCKCHAINS RELY ON OLDER CRYPTOGRAPHY

Many blockchains rely on decades-old elliptic-curve cryptography to create the public and private keys and digital signatures used to verify ownership of crypto assets and approve transactions.

Public keys are mathematically derived from private keys. In many blockchain networks, those public keys become visible once crypto assets are transferred or used in a transaction.

Today’s conventional computers cannot practically derive a private key from a public key. But a sufficiently powerful quantum computer could do so, allowing hackers to imitate digital signatures and approve fraudulent transactions.

The risk is especially important for public crypto networks because, unlike traditional payments, blockchain transactions generally cannot be reversed.

Utkarsh Ahuja, managing partner at Moon Pursuit Capital, said cryptocurrencies are unusually exposed because blockchains are transparent and permanent.

Bitcoin, the largest cryptocurrency, is viewed as particularly vulnerable because its 17-year transaction history has produced a large number of visible public keys.

According to an unpublished June 2026 working paper by independent researcher Ahmed Raza Muhammad Umer, about 35% of Bitcoin’s circulating supply could be exposed to a quantum-computing attack. Other research last year estimated that the figure could reach as much as 50%. A separate June 2026 academic paper said quantum risks to Bitcoin and Ethereum are real but remain bounded and largely mitigable if migration happens in time.

Cristiano Ventricelli, vice president and senior analyst for digital assets at Moody’s Ratings, said a single incident in which a hacker stole and sold a large quantity of cryptocurrency could sharply depress the affected token’s price, with market-wide consequences.

The risk has already led some investors to reconsider Bitcoin exposure. Christopher Wood, global head of equity strategy at Jefferies, removed a 10% Bitcoin allocation from his model portfolio in a January newsletter, citing the long-term existential threat posed by quantum computing.

BLOCKCHAIN UPGRADE PLANS TAKE SHAPE

Some industry representatives say quantum computers may still need several years before they can break blockchain security and that the crypto sector can use that time to move toward post-quantum cryptography.

But many crypto executives warn that moving too early could create new vulnerabilities because post-quantum cryptography remains a fast-developing field.

Post-quantum digital signatures are usually much larger than traditional signatures. That can increase storage and bandwidth requirements, potentially raising costs and weakening user experience, especially on networks such as Bitcoin that have fixed block-size limits.

Zach Pandl, head of research at Grayscale, said the industry faces an engineering challenge but also has possible engineering solutions available.

The transition could still take years. A senior cybersecurity executive at a major crypto company said his firm expects it would take about two years to become fully quantum-resistant. Some industry figures compare the effort to the Y2K transition, when more than $300 billion was spent globally to address the “millennium bug.”

The issue is more complicated for blockchains because many are decentralized and depend on community consensus over which solution should be adopted and when.

According to people cited in the Reuters report, none of the 20 largest blockchains has yet implemented a post-quantum signature algorithm. In Bitcoin, developers and market participants remain divided over the appropriate fix and the timing of any transition.

The Ethereum Foundation, which supports the Ethereum blockchain, says it has a dedicated post-quantum research team and is targeting 2029 for full post-quantum protection under its Lean Ethereum roadmap. Its public guidance says no quantum computer today can break Ethereum’s cryptography, but that migration planning is needed because cryptographic transitions take years.

Christopher Smith, CEO of Quantus, a blockchain that uses post-quantum cryptography, said the worst-case scenario would be the threat arriving much earlier than expected.

Algorand Foundation is among the early movers. The foundation, which supports the Algorand blockchain, published a post-quantum roadmap last month and said native support for post-quantum accounts is planned for its third-quarter 2026 protocol release.

Bruno Martins, chief technology officer at Algorand Foundation, said beginning work now was the responsible approach because the sector needs a plan before the threat becomes urgent.