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Quantum computers could create some problems for Bitcoin.
Four years ago it was hypothesized that it would take decades before quantum computers could actually be used on a large scale, for example, to mine Bitcoin.
A recent survey reveals instead that the times could be much shorter.
Summary
The survey
Recently, the results of a QuEra survey conducted on 927 people worldwide connected with quantum computing, such as researchers, executives, journalists, and enthusiasts, were published.
Among the various questions the participant answered, there was one in particular (the rhyme of section 7) dedicated to the future developments of quantum computing.
To the question “When do you expect quantum technology to become a better alternative to classical computing for certain workloads?” 37% responded within 6-10 years.
Only 23% responded after the next 10 years, while 24% responded between 4 or 5 years.
This is not a generic question about quantum computing, but limited to “specific workloads”, however, the answer suggests that the hypothesis is that they may actually be usable in the not too distant future, on historical timescales.
The survey also reveals that 41% of respondents believe that the pace of evolution of this technology is greater than expected.
The status quo
In order to achieve this, however, it is still necessary to resolve some issues.
The most significant factor is considered to be scalability, that is, the use of these technologies on a large scale and for a high number of operations.
We must not forget that at present quantum computers are very expensive, so it is still very difficult to imagine that they can spread.
The second major issue is related to errors, which currently makes this technology not really usable for practical purposes.
The third is actually the performance itself, which is precisely what in theory should be the greatest strength of quantum computers.
Therefore, the current state is one of a still very wide distance from widespread and concrete use, but the pace at which this sector is evolving seems to be accelerating.
The mining of Bitcoin
One of the most cited applications by the interviewees for quantum computing was the large-scale generation of random numbers.
It should not be forgotten that Bitcoin mining consists precisely in the generation of an enormous quantity, in a very short time, of random alphanumeric strings (hash) until the one that validates a block is guessed.
For example, one of the most powerful ASICs currently on the market generates about 16 Th/s, or 16,000 billion hashes in a single second.
In total, it is estimated that the overall hashrate of all Bitcoin miners in the world develops about 635 Eh/s, or more than 600 billion billion hashes every second.
Quantum computers could even elevate these numbers by several orders of magnitude, making current ASICs completely obsolete due to a clear lack of competitiveness.
However, this would be a problem only for the current miners, who could still solve it simply by replacing their ASICs with quantum computers.
Even if it only took a decade for this to happen, the miners would have plenty of time to adjust.
We remind you that Bitcoin is designed to continue functioning in the same way regardless of the computing power of the miners.
The other problems
The real risk for Bitcoin is another one.
In fact, the security of the Bitcoin protocol is based on a specific cryptographic algorithm, Secure Hash Algorithm 256 (SHA-256). This is used to generate public addresses from private keys.
According to the Cybersecurity and Infrastructure Security Agency (CISA) of the USA, in a distant future, quantum computers could be capable of breaking the public key encryption algorithms currently in use.
If they manage to break SHA-256 as well, it will be necessary to deeply modify the Bitcoin protocol, in order to replace this algorithm with another quantum-resistant one.
The problem is that modifying the Bitcoin protocol is extremely difficult.
That is, for such a change an hard fork would be necessary, and it is not at all certain that an hard fork will be accepted by the community of users.
In other words, there could be oppositions, to the point of making the update impossible, or generating a plethora of fork among which it could be difficult at first to identify the winning one.
Furthermore, even the modification itself of replacing the encryption algorithm could be very complicated from a technical point of view.
Fortunately, from this point of view, it seems that the timelines are more extended. To the point that in the same QuEra survey, the possibility that quantum computers will be used to violate older encryption algorithms is not even mentioned.
The solutions to the problems of quantum computers for Bitcoin
As for mining, the solutions are already in place. In fact, it will be enough to increase the difficulty, which already happens (and will continue to happen) approximately every two weeks.
For the security of generating public addresses from private keys, however, a specific effective solution has not yet been identified.
It should be remembered that, in the absence of a solution, with sufficiently powerful quantum computers, one could guess a private key that corresponds to a public address.
This would in fact allow all funds to be withdrawn from that address without anyone being able to oppose or cancel the operation.
The problem, however, is already well known, and the Bitcoin developers community is already thinking about possible solutions. Fortunately, there should be plenty of time to identify and test an effective one.