The cryptocurrency industry is beginning to prepare for a threat that once felt distant. Quantum computers powerful enough to crack the encryption protecting digital wallets and transactions.

Recent research and industry warnings have pushed the issue higher on the agenda, even though the technology remains largely experimental. The concern is not abstract.

The global crypto market depends on blockchains secured by older cryptographic systems, and those systems could become vulnerable if quantum progress continues to accelerate. Google has suggested encryption-breaking quantum computers could arrive by 2029, a far nearer horizon than many in the industry previously assumed.

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Explaining the quantum risk

At the centre of the risk is elliptic-curve cryptography, the decades-old method used by most blockchains to generate public and private keys and to verify ownership and transactions.

Public keys often become visible once crypto assets are used or transferred, which creates a potential opening for a sufficiently advanced quantum machine to derive private keys, forge digital signatures and authorise fraudulent transactions.

That danger is particularly acute for public blockchains, where transactions are irreversible once completed. “Crypto especially is uniquely exposed because blockchains are transparent and permanent,” said Utkarsh Ahuja, managing partner at Moon Pursuit Capital.

Chris Tam, head of quantum innovation at BTQ Technologies, called it “the most direct and existential threat” to cryptocurrencies and crypto networks.

Why bitcoin is in the spotlight?

Bitcoin is seen as one of the most exposed assets because its 17-year transaction history has left behind a large number of visible public keys.

An unpublished June 2026 working paper by independent researcher Ahmed Raza Muhammad Umer estimated roughly 35% of bitcoin’s circulating supply could be exposed to a quantum attack, while earlier research put the figure as high as 50%.

Moody’s Ratings analyst Cristiano Ventricelli warned that a major theft or sale of tokens could hit prices sharply, saying, “Everyone will feel the impact.”

The anxiety has already influenced portfolio decisions. Jefferies’ Christopher Wood removed a 10% bitcoin allocation from his model portfolio in January because of the long-term quantum risk.

The race to future-proof crypto

Crypto firms and blockchain developers are now weighing upgrades to post-quantum cryptography, but that transition could take years and may require sweeping infrastructure changes.

Executives said that moving too early could create fresh vulnerabilities, because post-quantum signatures are larger and can increase storage and bandwidth demands.

Zach Pandl of Grayscale said there is “an engineering challenge ahead” but added that there are “engineering solutions already on the table”. None of the top 20 blockchains has yet implemented a post-quantum signature algorithm, though the Ethereum Foundation is targeting 2029 for full protection and the Algorand Foundation has already published a roadmap and plans to support post-quantum accounts later this year.

“It felt right to start doing (something) now,” said Bruno Martins, Algorand Foundation’s chief technology officer.

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FAQs

Q1: Why are quantum computers considered a threat to cryptocurrencies?

Powerful quantum computers could eventually break the cryptographic algorithms that protect blockchain wallets and transactions.

Q2: What is post-quantum cryptography in blockchain?

Post-quantum cryptography refers to encryption methods designed to remain secure even against attacks from quantum computers.