Rumors continue to circulate in cryptocurrency forums and telegram chats that the reason for the recent impressive subsidence of the BTC rate was the news that Google achieved quantum superiority. This news, originally posted on the NASA website, and then , coincidentally coincided with a sudden drop in the power of the bitcoin network. Many thought this coincidence meant a hack and caused traders to dump a fair amount of bitcoin. Like, because of this, the course of the coin was flooded by as many as 1500 “dead US presidents”. The rumor stubbornly does not want to die and is fueled by the firm conviction of the public that the development of quantum computing is the guaranteed death of blockchains and cryptocurrencies.
The basis for such statements was the work, the results of which were shared in 2017 by a team of researchers who investigated the problem of “quantum threat”. In their opinion, the vast majority of crypto-protocols that provide transactions in distributed registries are vulnerable to powerful quantum computers. I analyzed the information published on the network regarding the so-called. “the quantum vulnerability of blockchains in general and cryptocurrencies in particular. Next - the results of the analysis and comparison of existing facts about the possibility of a successful attack on bitcoin.
A few words about quantum computers and quantum supremacy
Anyone who knows what a quantum computer, a qubit and quantum superiority is, can safely proceed to the next section, because they will not find anything new here.
So, for a tentative understanding of the threat that can hypothetically come from quantum computers, one should understand what kind of devices they are. A quantum computer is a predominantly analog computing system that uses the physical phenomena described by quantum mechanics to process data and transmit information. More specifically, quantum computers are used to compute и .
Thanks to the use of quantum phenomena in computational mechanisms, computing systems are capable of performing individual operations tens and hundreds of thousands, and in theory even millions of times faster than classical computers (including supercomputers). This performance in relation to certain calculations is due to the use of qubits (quantum bits).
A qubit (quantum bit or quantum discharge) is the smallest element in existence for storing information in a quantum computer. Like a bit, a qubit allows
“two eigenstates, denoted by {displaystyle |0rangle }|0rangle and {displaystyle |1rangle }|1rangle (Dirac notation), but can also be in their superposition, that is, in the state {displaystyle A|0rangle +B|1rangle } {displaystyle A|0rangle +B|1rangle }, where {displaystyle A}A and {displaystyle B}B are complex numbers satisfying {displaystyle |A|^{2}+|B|^{2}=1}| A|^{2}+|B|^{2}=1.”
(Nielsen M., Chang I. Quantum Computing and Quantum Information)
If we compare the classical bit, which contains 0 or one with a qubit, then the bit is abstractly a conventional switch that has two positions “on” and “off”. A qubit in such a comparison will be something resembling a volume control, where “0” is silence, and “1” is the maximum possible volume. The regulator can take any position from zero to one. At the same time, in order to become a full-fledged model of a qubit, it must also simulate the collapse of the wave function, i.e. at any interaction with it, for example, looking at it, the regulator must move to one of the extreme positions, i.e. "0" or "1".
In fact, everything is somewhat more complicated, but if you don’t get into the jungle, then thanks to the use of superposition and entanglement, a quantum computer will be able to store and operate on colossal (today) amounts of information. At the same time, it will spend much less energy on operations than classical computers. Thanks to the reliance on the phenomena of quantum mechanics, parallel computing will be ensured (when to obtain a valid result there is no need to analyze all options for potential system states), which will provide ultra-high performance with minimal power consumption.
At the moment, several models of promising quantum computers have been created in the world, but not one of them has surpassed the most powerful of the created classical supercomputers in terms of performance. Building such a quantum computer would mean achieving quantum supremacy. It is believed that in order to achieve this very quantum superiority, it is necessary to create a 49 qubit quantum computer. It was just such a computer that was reported in September on the NASA website, in a publication that quickly disappeared but generated a lot of noise.
Hypothetical danger to the blockchain
The development of quantum computing and quantum informatics, as well as active coverage of this topic in the media, provoked rumors that large computing power could become a threat to distributed registries, cryptocurrencies, and in particular to the Bitcoin network. A number of media outlets, mainly resources covering the topics of cryptocurrencies, annually publish information that quantum computers will soon be able to destroy blockchains. The authors of a study from Cornell University scientifically substantiated the hypothetical possibility of a successful attack by a quantum computer on the bitcoin network in 2017. . It is on the basis of this publication that most of the articles about “Prophecy 2027” are created.
When creating cryptocurrencies, one of the main goals is to protect it from data forgery (for example, when confirming a payment). At the moment, the use of cryptography and a distributed registry are quite coping with this task. Transaction data is stored on the blockchain, copies of the data are distributed among millions of network participants. In this regard, in order to change data on the network in order to redirect a transaction (steal a payment), it is necessary to influence all blocks, and this is impossible without the confirmation of millions of users. It turns out that at the level of data immutability, the blockchain is reliably protected, including from quantum computing.
Only the user's wallet can be problematic and vulnerable. This is due to the fact that for the foreseeable future, the power of a quantum computer may be enough to crack 64-digit private keys and this is the only hypothetically real possibility for any threat from quantum computing.
On the reality of the threat
To begin with, you should understand at what stage the developers of quantum computers are and which of them are really capable of cracking a 64-digit key. For example, Vladimir Gisin, an associate professor at the Financial University under the Government of the Russian Federation, said that the bitcoin blockchain can be hacked in a world where 100-qubit quantum computers exist. At the same time, even the existence of a 49-qubit quantum computer, allegedly developed by Google, has not yet been confirmed.
At the moment, there are no reliable predictions of when researchers will achieve quantum supremacy, much less when 100-qubit quantum computers will appear. Moreover, at present, quantum computing systems are able to instantly solve only a limited range of highly specialized tasks. Adapting them to hack something would take years, perhaps even decades, of development.
The exaggerated threat to bitcoin and other cryptocurrencies from quantum computers is also considered by Jeffrey Tucker, who substantiated his point of view in "The Threat to Bitcoin from Quantum Computing". Among other things, Tucker draws conclusions based on the work of a quantum physicist from Macquarie University in Sydney, Dr. Gavin Brennen. The Australian physicist is reasonably convinced that:
“Given the level of quantum computing power currently available, negative scenarios are impossible.”
Quote according to forklog.
Brennen believes that the current quantum infrastructure has a relatively slow quantum gate speed compared to that required to break a cryptographic key.
It is also important to understand that when assessing the quantum threat to blockchains, including BTC, researchers use data about their current state. Those. they estimate the risk of today's keys being broken by devices that will appear in 10, 15, and possibly 50 years.
Back in 2017, Nev Tsunich, director of data protection at IBM, said that measures to protect against the risks associated with quantum computing should be developed today. This statement has been heard, and is currently being actively developed , which has already developed methods for protecting blockchains from quantum attacks.
The most notable methods of protecting the blockchain from a so far hypothetical quantum threat have been the use of a one-time , as well as using и Merkle.
Sergey Arestov, co-founder of the infrastructure and mining company BitCluster, is convinced that the existing methods of new post-quantum cryptography will nullify any efforts to hack the blockchain in the next 50 years. The crypto entrepreneur gave examples of projects that already take into account the risks associated with the development of quantum computers:
“Today, there are already projects such as the Quantum-Resistant Ledger, which uses the Winternitz one-time signature algorithm and the Merkle tree, as well as the quantum-resistant IOTA and ArQit blockchains. It is likely that by the time there are at least hints of creating something capable of cracking the keys of bitcoin or ether wallets, these coins will also be protected from quantum computing, one of the promising technologies.”
As a conclusion
After analyzing the above, we can confidently say that quantum computers do not pose any serious threat to cryptocurrencies and blockchains in the foreseeable future. This is true both for newly created systems and for existing ones. The danger of hacking distributed ledgers and decentralized currencies should be taken more as theoretically possible (provoking the creation of more secure systems) than as any probable reality.
The problems leveling the probability are the following:
- "raw" quantum computing and the need to adapt them for the corresponding operations;
- lack of computing power in the near future (“quantum superiority” as such does not guarantee that a 64-character key will be cracked);
- using post-quantum cryptography to secure the blockchain.
I would appreciate the opinions and lively discussion in the comments and participation in the survey.
Important!
Crypto assets, including Bitcoin, are extremely volatile (their exchange rate changes frequently and dramatically), exchange speculation strongly influences changes in their exchange rate. Therefore, any investment in cryptocurrency - this is a serious risk. I would strongly recommend investing in cryptocurrencies and mining exclusively to those people who are so well off that if they lose their investments, they will not feel the social consequences. Never invest the last money, targeted significant savings, limited family assets in anything, including cryptocurrencies.
, as well as a photo .
Only registered users can participate in the survey. , you are welcome.
Do you think quantum computing will become a real threat to cryptocurrencies and blockchains in 10 years?
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yes, the author and experts underestimate the speed of technology development
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no, but in 15 years they will pose a serious danger
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no, it takes much longer
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yes, the secret services and reptilians have long had a quantum supercomputer capable of hacking any blockchain
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difficult to predict, not enough reliable data to predict
98 users voted. 17 users abstained.
Source: habr.com