Crypto is the canary in the coal mine for the quantum computing threat, experts say

As estimates for “Q-Day” move closer, experts warn that crypto’s slow governance, not its cryptography, may be the biggest obstacle to defending against quantum attacks.

• Quantum computing could first expose vulnerabilities in crypto networks, positioning Bitcoin as an early warning system for broader financial infrastructure risk.
• The real bottleneck is governance, not cryptography, as Bitcoin’s slow, consensus-driven upgrade process lags behind centralized institutions.
• “Q-Day” is a gradual threat, not a single moment, with attackers needing only enough quantum power to break encryption before assets lose value.

Quantum computing is a risk factor for every encrypted system on the planet, including major banks. But crypto, due to the way it works, may be the technology that gets tested first.

"Cryptocurrencies are the canary in the coal mine," Eddy Zervigon, CEO of Quantum Xchange, said in an interview with CoinDesk. Zervigon's firm builds infrastructure to shield networks, including financial ones, from quantum-enabled attacks, and he's blunt about where the first casualty is likely to show up.

"That's the first place of attack because of the decentralized nature," Zervigon said. "Once you see it happening there, then you know that someone somewhere has a cryptographically relevant quantum computer."

A cryptographically relevant quantum computer, capable of breaking the elliptic-curve cryptography underpinning the Bitcoin blockchain's signatures, along with the encryption securing bank rails, doesn't exist yet. The consensus estimate for when it will is compressing, not stretching.

"The folks spending billions of dollars, like Microsoft, IBM, and others developing quantum computers, generally believe there will be a commercially relevant, cryptographically relevant quantum computer in the 2029 timeframe," Zervigon said. "That's not me making stuff up. That's based on what people like Arvind Krishna at IBM have said."

That estimate is consistent with recent hardware developments. Earlier this year, Google researchers revealed that breaking the elliptic-curve cryptography safeguarding top cryptocurrencies like bitcoin and ether would require fewer than 500,000 physical qubits, a 20-fold decline from previous estimates. That prompted several observers, including Google, to pull forward the so-called Q-Day deadline to 2029.

The White House, meanwhile, is aiming to develop a powerful quantum computer by 2028 and shift high-value assets and federal data to post-quantum cryptography by 2030. "That sets the clock. It creates a sense of urgency,” Zervigon said.

Consensus speed is the real risk factor

Zervigon isn't alone in pointing to slow governance, not cryptography, as crypto's weak point.

Deutsche Digital Assets framed it as a clear cut speed differential between TradFi and decentralized rails.

"The difference — and this is the honest answer to the 'Bitcoin is uniquely vulnerable' narrative — is governance speed," the bank wrote on July 23.

It explained that an investment bank like JPMorgan does not need to get a go ahead from millions of pseudonymous global participants before upgrading its cryptographic infrastructure.

“It needs a board resolution, a budget, and a vendor. Large financial institutions can and will migrate to post-quantum standards faster, more quietly, and more predictably than a decentralised public blockchain. That is not an argument against Bitcoin. It is an argument for taking its governance process seriously,” Deutsche Digital Assets added.

Academic literature, such as the 2024 arXiv paper "Downtime Required for Bitcoin Quantum-Safety" validates this argument citing Bitcoin's own upgrade history as the cautionary precedent.

"Before any upgrade process can be commenced, a 90% consensus among Bitcoin miners has to be achieved over the particular details of the upgrade," the researchers wrote. "Historically, considerable changes to the Bitcoin network have been met with high resistance. A notable example of this was the SegWit upgrade in 2017."

That upgrade triggered disagreement in the community to such an extent that the Bitcoin blockchain eventually split into several different versions through hard forks, creating the Bitcoin Cash and Bitcoin Gold networks.

The takeaway, therefore, is that post-quantum cryptography itself could be ready in time. What's uncertain is whether Bitcoin's governance layer can arrive at a 90% consensus to deploy the defenses.

Q-Day isn't a print, it's a trend

Markets tend to model this as a binary event, where encryption holds until a specific date, then it doesn't. Zervigon says that framework is wrong, and it understates how early the risk actually bites.

"Everybody talks about the moment you can break an algorithm," he said. "You don't necessarily need to do it in one moment to be effective. If it takes me three months or six months to decrypt data that still has value, I've achieved the same goal."

That collapses the usual timeline math. A quantum computer doesn't need enough throughput to break a signature in real time to be a threat, it only needs enough throughput to get there before the underlying data or funds stop being worth stealing.

AI Disclaimer: Parts of this article were generated with the assistance from AI tools and reviewed by our editorial team to ensure accuracy and adherence to our standards. For more information, see CoinDesk's full AI Policy.

Crypto Flows, Share and the Selective Rotation

Crypto Flows, Share and the Selective Rotation

Markets repositioned since June, but Binance held share (~55% user funds, ~24% spot) and drew net inflows in early July while the tracked market saw outflows.

Markets repositioned since June, but Binance held share (~55% user funds, ~24% spot) and drew net inflows in early July while the tracked market saw outflows.

Why it matters:

Markets repositioned since June, but Binance held share (~55% user funds, ~24% spot) and drew net inflows in early July while the tracked market saw outflows.

View Full Report