Quantus founder warns: first quantum attack or replica vulnerability on cryptocurrency

Quantum computing and cryptocurrency: First attacks may be difficult to detect

In the cryptocurrency field, quantum computing is often portrayed as the doomsday scenario in the future-sometimes even around the assumption that once "Q Day" arrives, Satoshi Nakamoto's sleeping bitcoins may be looted. But Christopher Smith, CEO and co-founder of Quantus Network, believes its first real-world impact may be far less dramatic: not an overt, evidence-friendly hack, but a series of wallet intrusions that are difficult to attribute to quantum capabilities.

Smith pointed out that once quantum computers are powerful enough to crack the public key cryptosystem used by mainstream blockchains, attackers may derive private keys from public information on the chain. The key is that this breached path may not trigger obvious security failures within the wallet or exchange, leaving investigators with little evidence to confirm that no meaningful intrusion was detected.

Core Points

Q-day attacks can be difficult to detect because attackers do not need to breach wallets, devices, or exchange infrastructure to carry out attacks. The targets of early quantum attacks may not be limited to "Satoshi Nakamoto's Bitcoin", but also include high-value management keys and other sensitive systems. Security researchers believe that attackers are more likely to prioritize targeting exchanges 'hot wallets because these targets are not easy to trigger alerts quickly. Predictions about when quantum computers can crack modern elliptic curve codes range from possibilities in the late 2020s to almost certainty in the early 2030s. The blockchain team has begun to migrate backward quantum signatures, mainly because the risk of waiting for certainty is too high.

Why quantum theft may be indistinguishable from "ordinary" intrusions

Smith's core warning is that quantum attacks may not leave clear forensic traces. "When someone cracks your key, you don't get a memo explaining how they did it," he said in an interview. In this scenario, once they have sufficient quantum computing power, the attacker can use the information already on the public blockchain to calculate the corresponding private key.

This change in attack mechanism is important for event response. Smith pointed out that if a highly secure organization is attacked,"the only forensic evidence is that there was no intrusion." Attackers do not need to use the system in which the wallet is running, nor may they leave traces in the logs that point to traditional intrusion paths.

As a result, security expectations may not be consistent with the earliest manifestations of quantum-driven theft incidents. If investigators look primarily for device-level intrusions, key management failures, or exchange-side intrusions, they may not be able to detect the traditional indicators that accompany catastrophic key losses.

The first targets may be more strategic than the "famous" targets

Most public concerns about Q-Day have focused on Satoshi Nakamoto's positions estimated to be worth about US$63 billion. Smith believes that while this narrative has dominated the headlines, the earliest targets of quantum attacks may be elsewhere.

According to Smith, the earliest high-value targets may include military systems and state secrets. In the crypto ecosystem, he specifically pointed out that the "most valuable single key" may be the coinage key of Tether. According to him, quantum attackers can mince tokens from management wallets and sell them before the issuer responds.

He also pointed out that USDT is deployed on multiple networks, some of which are already undergoing post-quantum migration. This detail highlights an important practical issue: Even if stablecoins are widely used, the risks are not limited to user wallets. Management keys or coinage keys-as well as other privileged cryptographic roles-may be where quantum attacks cause the greatest financial losses.

Another point of view comes from blockchain capital security researcher Sean Chetham. He believes that attackers are more likely to target exchanges 'hot wallets, especially those that "don't sound alarms," than try to seize well-known holding coins. Chetham's comments suggest that attackers may optimize timing and operational resistance: Quantum capabilities may not eliminate the value of targeting, but simply change the way an invasion is achieved.

Smith added a more nuanced situation: An attacker can cover up quantum theft with seemingly reasonable, deniable explanations. "It's also possible that they... give these seemingly reasonable, deniable explanations: 'Oh, someone just somehow lost the key,'"he said. This increases the possibility that quantum-related events will be misjudged as ordinary losses or traditional intrusions.

The timing of the Q-day is still uncertain, AI is reshaping the assumption

Part of the reason why the Q-day is difficult to plan is that predictions have been changing as quantum advances and related algorithms improve. There are reports that Google has advanced its subsequent quantum migration schedule to 2029, citing AI-assisted breakthroughs that show that elliptic curve codes can be cracked with fewer physical qubits.

In current reports, NGRAVE CEO Roy Blackstone criticized early quantum threat models, arguing that they did not fully account for the parallel development of AI. He cited the view that many threat models assume sufficient time before public-key cryptography is cracked, but fail to reflect the speed at which AI and quantum research are developing simultaneously.

Despite the urgency, there is still no consensus on when quantum computers can crack modern cryptography. Smith, whose company is building a blockchain network that has quantum resistance from launch, said that there is a "50-50" possibility of Q-Day coming in 2028, and believes that the continuous improvement of quantum algorithms with AI assistance and hardware research makes predictions even more unreliable.

Chetham's view is that the early 2030s are "almost certain", while earlier dates are "more like trailing probabilities." Michael Coates, chief information security officer at the Solana Foundation, declined to give an estimate in an earlier interview, saying it was "impossible to know." He also pointed to a long-standing industry model: "It's always five years away," a view he believes has lasted for more than a decade.

Even if predictions vary widely, the theme these experts emphasize repeatedly is that uncertainty should not be a reason for procrastination. Blackstone emphasized that blockchain has begun to migrate backward quantum signatures because "if it does not, the damage will be catastrophic."

What post-quantum migration means for cryptocurrency security

The actual meaning of these warnings is straightforward: As quantum timetables change, migration cryptography is the only way to reduce exposure. While Q-Day may be difficult to predict accurately, changes in risk models make "wait and see" a poor strategy-especially because early quantum attacks can be indistinguishable from other security failures.

Therefore, post-quantum signature migration is not just about long-term research alignment. It changes what defenders may encounter in real events. If a chain adopts post-quantum signatures, it will shorten the window for attackers to use quantum computing to crack public key weaknesses. This also reduces the likelihood that theft will be mistakenly attributed to traditional intrusions.

It may also affect how exchanges and institutional custody service providers prioritize key management and operational security. If an attacker can derive private keys without having to "hack" the system, the strongest defense becomes cryptographic resilience, not just the reinforcement of boundaries and devices.

The next question readers should focus on is how fast quantum signatures migrate after major ecosystems are completed, and whether their migration schedules take into account the impact of AI on accelerating quantum research. If the earliest quantum attacks appear to be no different from ordinary attacks, the timing of the migration-and the consistency with which it is implemented across the network and management key roles-may be as important as any single "Q-day" date.