Bitcoin braces for a quantum computing onslaught

Quantum computing, the prospect of advanced computations beyond the binary limitations of ones or zeros, may be the harbinger of advancements to come. But cryptocurrency adherents are starting to wonder if their digital monetary system is ready for what this new age of data processing might bring.

Preparing for a 'potential catastrophe'

The "technological leap" of quantum computing could "pose new risks" to cryptocurrency users and potentially "undermine the cryptographic backbone of blockchain," said quantum computer developer Yuval Boger at Forbes. Although the "immediate risks are low," the future could see "large-scale, error-corrected quantum computers" capable of running algorithms that could break the elliptic curve cryptography (ECC) used by bitcoin as one of the industry's main security protocols.

While current quantum computers "aren't yet powerful enough," the "risk is real in the long term," said Isaac Kim, a computer science professor at UC Davis, in a recent interview with the crypto research firm Presto Labs. Despite "slight differences" between the levels of risk for each different type of cryptocurrency, "any blockchain that uses ECC, like bitcoin and ethereum, are vulnerable."

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"Crypto is underprepared," researcher Rick Maeda said in an interview with CoinDesk on Monday. "The biggest risk is just waiting too long."

Although some members of the crypto community are willing to "shrug off" the looming threat posed by quantum computing, "behind closed doors," a number of leading figures in the field are "concerned about a potential catastrophe," said Decrypt. Experts now believe the industry has "less than a decade, even a handful of years" to enact "contingency plans." And even that might be optimistic: A new paper published last month by Google Quantum AI researcher Craig Gidney suggests that the RSA encryption used by bitcoin could be overcome using "20 times fewer quantum resources than previously estimated," Benzinga said.

'Post-quantum' protections

Given how serious the threat to cryptocurrency from quantum computing is, a "proactive approach" is "critical" to preempt disruption to an industry worth hundreds of billions of dollars annually, researchers from the University of Kent's School of Computing said in a late 2024 study detailing what such an approach might look like. The only way to prevent wide-scale quantum disruptions for an asset like bitcoin, the authors said, is "to upgrade — replace — the currently used public-key cryptosystems" to ones that have "no known vulnerabilities to quantum attacks." This is known as "post-quantum cryptosystems."

That type of complete "protocol update" would "take the cryptocurrency offline for 76 days," Fortune said. More "realistically," bitcoin could dedicate just a quarter of its server space to the upgrade — allowing users to "continue to mine and trade at a slower rate" — in which case the downtime would last an estimated ten months.

Broadly, that downtime risk speaks to what Maeda said is a "key barrier" to addressing the looming challenge. "It's difficult to create a way to monetize this," Maeda said to CoinDesk. But those preparations need to happen sooner rather than later, he added. "We can't wait until the threat is real to start taking it seriously. By then, it's already too late."