The science of quantum physics is being used to build quantum computers–powerful machines that have the ability to solve incredibly complex mathematical equations much more quickly than even the most advanced computers available today.

As such, any data that’s encrypted using mathematical equations–including banking data, intelligence data protected by the government, and encrypted messages on cell phones–is vulnerable to being exposed by quantum computing. Most notably, in this case, encrypted cryptocurrency data–such as private wallet keys–are also vulnerable to quantum computing technology.

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In other words, quantum computing could potentially be used to uncover every private key on a blockchain network, thus rendering that network’s users vulnerable to hacking and theft.

Therefore, the point in time at which quantum computers can solve problems that ordinary computers cannot–also known as the “quantum supremacy”–is considered to be a serious threat to the security of blockchain networks.

## Qubits and the “quantum supremacy”

How far away are we from this “quantum supremacy”?

“Last week,” joked Kadan Stadelmann, CTO of Komodo, a multichain architecture project, to *Finance Magnates. *

In any case, “jokes apart, from a technical standpoint we have to consider the ‘quantum supremacy’ era already here – now. The industry leaders in this area have already publicly presented functional two to three-figure qubit chips, which means with ‘unlimited’ resources and space this could be scaled up quite fast.”

“Google, for example, just presented how their 54 Qubit chip performed a computation which would take the world’s most powerful supercomputer 10,000 years in just 200 seconds. This doesn’t even cover the non-public segment of this industry.”

Google has achieved “quantum supremacy.” Just what the heck is that? https://t.co/yuJDq6SxiY

— TIME (@TIME) November 11, 2019

What are “qubits”? While a classical computer uses “bits”, which are represented either 0s or 1s. Qubits, on the other hand, can be 0s or 1s–or both at different times. Qubits are the thing that make quantum computers so powerful: if a normal computer is operating with four bits, that computer could arrange those bits in any of 16 combinations, one after the other, in order to solve an equation.

With four qubits, however, a quantum computer could arrange four qubits into 16 combinations all at one time. According to *Decrypt*, “just 20 qubits can store more than a million values in parallel, which allows a quantum computer to be able to work through a problem by performing calculations in parallel rather than one at a time.”

## ”The threat posed by quantum computers is more likely to concern the vulnerability of personal cryptocurrency accounts or wallets.”

However, Vlad Miller, CEO of the Ethereum Express company, explained that blockchain network ledgers are not susceptible to hacking by quantum computers.

“Today, records of all cryptocurrency transactions are stored on blockchain. Since the copies of the data are distributed among all users, they are almost impossible to change,” he said. “No data block can be removed or modified without affecting all other blocks, which would require the consent of most network users. In this sense, blockchain is resistant to quantum computers, and the growth of computing power will not affect the security of the system.”

Indeed, “the threat posed by quantum computers is more likely to concern the vulnerability of personal cryptocurrency accounts or wallets. These powerful computers can hack user codes that are used to authorize transactions.”

“[…] Until recently, this was considered mathematically impossible,” Miller continued. “An ordinary binary computer is not able to crack a cryptocurrency key, but for quantum machines, this is not difficult because of the incredible computing power.”

Charles Phan, Charles Phan, CTO of Cryptocurrency Derivatives Exchange Interdax, also pointed out to* Finance Magnates* that “the SHA-256 function used in mining is another area where quantum computers could influence bitcoin [and] crypto. However, the risk is much lower here.”

“An adversary with a quantum computer could also direct it towards mining bitcoin – if they achieve 51% control of the hash power, then they can permit double-spending and do what it likes. They could also cause damage to the network if they control a significant proportion less than 51%.”

## ”Eventually, quantum computers will force changes in cryptocurrency systems.”

How immediate is the threat of quantum computing to blockchain networks, and what can these networks do to protect themselves?

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“Eventually, quantum computers will force changes in cryptocurrency systems, but today’s quantum computers exist only in the lab and are a long way from having practical impacts on cryptocurrencies,” said Edward Felten, Co-Founder and Chief Scientist of Offchain Labs, a second-layer scaling solution for Ethereum, to *Finance Magnates*. Ed is also the former White House Deputy United States Chief Technology Officer.

“Over time, cryptocurrencies will need to evolve to use different encryption and hashing methods that are quantum-resistant. Crypto communities should be talking about how to do this, but it’s not yet an emergency.”

At what point will it become an emergency? Vlad Miller said that although the United States National Security Agency predicted in 2016 that “decades” would pass before quantum computers pose a serious threat to encrypted information, “given the pace of development of this technology over the past year and a half, the conclusions of the NSA seem overly optimistic. In fact, many experts believe that the threat will arise in the next 15 or even 10 years.”

## Preparing for the “quantum supremacy”

Therefore, a number of blockchain projects are already preparing for this “quantum supremacy.”

Kadan Stadelmann explained that “while [quantum computers] certainly pose a long-term threat to most cryptocurrencies in their current form, the more legitimate projects are already deploying countermeasures in the form of quantum-proof cryptography.”

People ask me about Google’s quantum computer. I am skeptical. There have been false alarms before. But if their results are reproducible and testable by other groups, then it might be a game changer. We have to wait and see before making final judgement.

— Dr. Michio Kaku (@michiokaku) November 6, 2019

“Even already existing cryptocurrency networks will be able to migrate to quantum-resistant algorithms and digital signature schemes,” he said.

Therefore, “by the time quantum computers are ‘available’ to the wider public, expect most remaining cryptocurrencies to have already made the leap into the quantum-resistance movement (so to speak.)”

## The threat of quantum computing is a solvable problem for crypto–but only if consensus on a solution can be achieved

However, this may be easier said than done–”metaphorically [speaking], pre-existing chains can already flip a switch and immediately deploy a quantum-resistance mechanism,” Stadelmann said to *Finance Magnates*. However, networks that have historically found it difficult to reach consensus on important software upgrades (for example, the Bitcoin network) could potentially run into trouble.

“If a quantum computer breaks this cryptography used by Bitcoin, anyone who has re-used a bitcoin address is vulnerable,” Charles Phan explained. However, “the information a quantum computer needs isn’t available until the first transaction from a public key is seen, so individuals who use a different public key each time would be safe.

Why quantum computing could be as important for @Google as artificial intelligence https://t.co/XXaN2mQsHS

— MIT Technology Review (@techreview) November 6, 2019

Still, though, “quantum processors threaten only the modern generation of cryptocurrencies like bitcoin,” Vlad Miller explained to *Finance Magnates.*

“To protect them, users will have to switch to new authentication methods for authorizing transactions in blockchain-based networks.”

Indeed, “the solution to this problem will be new methods of cryptography resistant to quantum computing. Today many crypto companies are developing a wide range of such solutions. Some of them are based on long-discovered mathematical methods, such as Lamport’s signatures, Merkle structures, and the sharing of secrets.”

Therefore, it is quite likely that blockchain networks will be secure from the threat that quantum computing poses. “Platforms will ‘change their locks’ once quantum computers start to move out of the lab,” said Matthew Hine, co-founder and CEO of enterprise blockchain software company He3Labs, to *Finance Magnates.*

“But everyone should be very hesitant to publicly publish encrypted information with the expectation that it will be secret forever.”