Why does Citi think Bitcoin faces higher quantum computing risk than Ethereum?

Citigroup analysts argued that Bitcoin’s governance structure makes it harder to implement major security upgrades quickly. In contrast, Ethereum has historically adapted more rapidly through regular protocol updates.

What is the quantum computing threat to cryptocurrencies?

Quantum computers could theoretically break the cryptographic systems protecting blockchain wallets and transactions. If powerful enough, they may derive private keys from public keys and gain access to digital assets.

How soon could quantum computers threaten Bitcoin encryption?

Citi said recent advances shortened estimates for practical quantum attacks to around 2030 to 2032. Some researchers believe the threat timeline could arrive even earlier.

Why are Bitcoin transactions potentially vulnerable to quantum attacks?

Bitcoin transactions temporarily expose public keys before settlement confirmation. A sufficiently advanced quantum computer could theoretically use that exposed information to calculate the corresponding private key.

Does a quantum computer capable of breaking Bitcoin exist today?

No. The report cited Google research suggesting a future 500,000-qubit machine could potentially break current Bitcoin encryption within minutes, but such hardware does not yet exist.

Why is Bitcoin governance considered a challenge for quantum upgrades?

Bitcoin’s decentralised governance model requires broad consensus across developers, miners and network participants. Major upgrades often take years of debate and testing before implementation.

What is a hard fork and why might Bitcoin need one?

A hard fork is a major blockchain protocol change that creates new rules incompatible with previous versions. Bitcoin could potentially require a hard fork to migrate fully toward quantum-resistant cryptography.

Why could Ethereum adapt faster than Bitcoin?

Ethereum has a history of more frequent network upgrades and governance coordination. Citi said proof-of-stake systems may be operationally more flexible when implementing future security changes.

Cryptocurrency

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Citi warns Bitcoin faces higher quantum risk

Written by Mahathir BayenaPublished May 19, 2026, 5:20 AM

Citigroup analysts warned that advances in quantum computing are accelerating potential risks to cryptocurrency networks, with Bitcoin viewed as more exposed than Ethereum due to governance and upgrade challenges.

The report said recent developments shortened estimates for practical quantum attacks on digital assets to between 2030 and 2032, with some researchers suggesting the threat could emerge even earlier.

According to the analysts, Bitcoin transactions temporarily expose public keys before settlement, theoretically allowing sufficiently advanced quantum computers to derive private keys and redirect funds.

Google research cited in the report suggested a 500,000-qubit quantum computer could potentially break current Bitcoin encryption within minutes, though such hardware does not yet exist.

The analysts argued Bitcoin’s conservative governance structure could complicate migration toward quantum-resistant cryptography because implementing major security upgrades would likely require broad consensus and potentially a hard fork.

In contrast, the report said proof-of-stake networks including Ethereum may be better positioned to adapt because of their history of more frequent protocol upgrades and flexible governance systems.

Citi estimated between 6.7 million and 7 million dormant Bitcoin remain stored in wallet formats with publicly exposed keys, including roughly 1 million Bitcoin believed to belong to Satoshi Nakamoto, potentially making them long-term targets for future quantum attacks.

At the time of reporting, Bitcoin price was $76,800.08.