Quantus CEO: The crypto industry risks running out of time to prepare for Q-Day

​Quantum computers are not yet capable of breaking blockchains on a large scale, but the crypto industry may have less time to prepare than many assume. Quantus CEO Christopher Smith explains why digital signatures would be the first target, why Bitcoin faces a more difficult transition to post-quantum security than other blockchains, and how AI could accelerate the threat. In an interview with Traders Union, he also explains why he believes someone may already possess a sufficiently powerful quantum computer and what could happen if the crypto industry fails to complete the transition in time.

Q-Day may be closer than expected

– IBM made quantum computing accessible by a wider audience back in 2016. Why has quantum security become such an urgent topic now? Who is most at risk from advances in quantum computing? 

– Quantum technology has been around for decades. Atomic clocks and lasers date from before the 1970s. Quantum computing’s theoretical foundations were laid in the 1980s and Shor’s algorithm (the one everyone is worried about) was discovered in 1994. 

Everyone is suddenly talking about it 30 years later because it took that long to develop quantum computing to the point where it could realistically run Shor's algorithm. People are worried about Shor's algorithm because it can efficiently solve certain mathematical problems that were believed to be hard. These problems form the foundation of modern cryptography, which secures many types of information, from military secrets and online financial transactions to most blockchains.

Once quantum computers can run Shor’s algorithm, all these systems will have to upgrade their cryptography. Many technology companies have already started migrating to post-quantum cryptography. Unfortunately blockchains are the hardest systems to upgrade. There is over $2 TRILLION at risk in the crypto industry that needs to move to post-quantum solutions and there aren’t many currently available.

– How close are we to a quantum computer capable of breaking the cryptography used by today’s blockchains? At what point will we be able to say that the threat has become practical rather than theoretical? 

– This is a difficult question to answer for several reasons. The first is that technological development is not linear. It happens in fits and starts. It’s unpredictable.

The second is that AI is accelerating everything, especially quantum. The best way to see this is to study https://ecdsa.fail. A few months ago, Google developed a much more efficient version of Shor's algorithm, but the U.S. government gave them a gag order because it was concerned about adversaries such as China using it. Google eventually published the paper, but without revealing the details of the algorithm.

A few weeks later, a crypto team called EigenLabs said, "Let's see what's in the box," and created an open platform where anyone could use AI to improve on the best publicly known algorithm. It took the open-source community only three days to match Google's results, and over the following month they nearly doubled the algorithm's performance. Soon after, President Donald Trump issued an executive order dramatically shortening the timeline for U.S. government agencies to migrate to post-quantum cryptography. This shows that the U.S. government dramatically underestimated AI's impact on quantum computing.

The third reason predicting Q-Day is difficult is national security. We should assume that quantum hardware labs are also subject to gag orders and are using AI to accelerate their progress. Since it will take years for blockchains to migrate, we should take this threat seriously immediately.

– Blockstream CEO Adam Back has argued that quantum computers are unlikely to pose a practical threat to Bitcoin for another 20-40 years, while other experts believe the transition should begin now. Why do opinions differ so widely, and which view do you find more convincing?

– Well everyone is always talking their book, and Bitcoin has the hardest migration path of all blockchains due to its (likely) dead founder and “decentralized” decision making. Quantum skeptics would have been right for the last 20 years, so it’s a logical default position to take. However, almost nobody agrees with Adam Back’s timeline today. Scott Aaronson, Eli ben-Sasson, Vitalik Buterin, the Five Eyes Intel Agencies, international banks, Google, they all have much shorter timelines. My personal position is that somebody already has the quantum computer and they are worried about someone else getting it and using it against them.

Bitcoin faces the hardest migration

– Which elements of a blockchain are likely to become vulnerable first to quantum attacks: digital signatures, wallets, consensus mechanisms, or mining? 

– The digital signatures are the vulnerable component. This covers transaction authorization as well as block validation in proof-of-stake systems. It also covers ZK-SNARKS, used by privacy chains and roll-ups, but not ZK-STARKS which is a hash-based version of the same tech. Mining is based on hashes, which is much less vulnerable to quantum attacks. The rule of thumb is “hashes good, elliptic curves bad”.

– Why is upgrading an existing blockchain for post-quantum security more difficult than building a new quantum-resistant network from scratch?

– The older blockchains are hard to upgrade because they lack on-chain governance systems. Newer chains generally have mechanisms to do an upgrade, which eases the transition significantly, but the real issue is the migration. Signal, iMessage and CloudFlare already went post-quantum and nobody noticed, because the engineers just handled it and these are centralized systems so users didn’t have to do anything. 

In the case of blockchains, users manage their own keys, so they have to take an action to become quantum secure and many people do not have easy access, or any access at all, to their keys, which adds more friction. We like to say, the pre-quantum blockchains have a migration problem. New chains have an adoption problem.

– BlackRock, Coinbase, Strategy, and several other companies have committed $15 million to improving Bitcoin’s security, including preparations for quantum threats. Is that a meaningful investment, and is it enough to make a difference? 

– Unfortunately the bottleneck is not money, nor is it technical. The defensive algorithms “post-quantum-cryptography” already exist and have good implementations. AI makes it easy to update and audit the code. These things are the problem. It’s the migration from old keys to new. That could take 1-2 years for Bitcoin. Meanwhile, Bitcoin has only 7 transactions / second (TPS), but the keys and signatures for post-quantum-cryptography are much larger so Bitcoin’s TPS is about to drop way below 1. It’s clear that the institutions want Bitcoin to survive, but unfortunately the crypto industry bet the farm on elliptic curves.

What quantum-resistant really means

– Many blockchain projects describe themselves as quantum-resistant. What technical criteria should a network meet before that claim can be considered credible rather than marketing? 

– It should have no elliptic curve signatures anywhere in it, but especially not for consensus or transaction authorization. Having a post-quantum option for users, like Algorand and NEAR, is a great start, but expecting your users to be proactive about the esoteric topic of cryptography is a bit optimistic. 

– One of Quantus’ products is a cryptocurrency wallet. What specific problem does it solve better than existing wallets, and why should the average crypto user start thinking about quantum security today?

– Many crypto wallets are under pressure to extract as much value from their users as possible, which leads to things like offering leveraged trading (gambling) on memecoins. This not only invites ruin for less financially sophisticated users, but also dilutes the original crypto mission of “better money”. Quantus believes you shouldn’t have to be a cybersecurity expert to secure your crypto, and we have achieved a very fast, secure, easy to use crypto wallet that is focused on money, not gambling.

– In June, President Donald Trump signed executive orders aimed at advancing quantum technologies and strengthening U.S. protection against cryptographic attacks. Should the transition to post-quantum cryptography be coordinated by governments, or should it be led by technology companies and the open-source community? 

– Both the private and public sector depend on cryptography. Governments, companies and the open source community all need to do their part. Governments are naturally quite involved in the development of cryptography due to its relevance to war, which has led to a variety of problems in the past where cryptography was intentionally and secretly weakened by spy agencies. 

One of the great gifts of blockchain as an industry was the private funding and development of cryptography for commercial use, something that didn’t really exist before. NIST did an eight-year international tournament to develop post-quantum-cryptography which is a pretty good process for reducing the risk of malicious interference in the design of these algorithms. A total of 278 cryptographers from 25 countries across six continents participated, making it extremely difficult for any single party to influence the outcome.

Likewise the commercialization of these algorithms is a different challenge. It requires practical implementation decisions that governments may not be best positioned to make. That's why governments, technology companies, and the open-source community all have an important role to play. 

The migration cannot wait

– Which systems should migrate to post-quantum cryptography first, and how urgent is the transition for blockchains, banks, payment networks, hardware wallets, and communication platforms?

– I don’t think this should be approached as a waterfall process. Every industry should begin migrating now if it has not already done so. Wallet providers, for example, cannot fully activate new signature schemes until the underlying blockchains support them, which adds another layer of complexity. Meanwhile, “harvest now, decrypt later” poses a greater risk to banks and governments because most blockchains are transparent by design.

The urgency is growing because we are rapidly approaching the point at which the time required to complete migration may exceed the time remaining until Q-Day. Once that happens, a significant amount of capital could leave the crypto industry altogether, while some of it may flow into post-quantum blockchains such as Quantus.