I don't believe Quantum Computing will ever threaten Bitcoin

[Macadonian]

... Then we get into the possibility of power from nuclear fusion. I know it's one of those things that is always 'a few years away' - but cheap energy (free? unlimited?) is getting closer all the time.

I think this kind of highlights the fact that technology is racing ahead of us, and it won't be long before it goes way beyond the ability of mere humans to understand, and it is computers themselves doing the thinking and theorising. The most promising form of defence against quantum attacks currently under development seems to be NTRU, which relies on some quite esoteric lattice-based maths which is frankly already beyond my ability to comprehend. In a few years' time I can imagine that it is computers themselves coming up with these models, and humans struggling to keep up. It's an infinite arms race into the distance really. So long as there is one side attacking and another side defending, it's difficult to see where it will stop - unless there is some fundamental facet of quantum mechanics that provides a final barrier to one or both sides.

Nuclear fusion is something which is getting closer by the day in fact in Boston they recently got a 50 million dollar dollar investment for their nuclear reactor. They believe they've sussed out the laws and its only a matter of building the plant. The theory has always been there and theoretically its safer than other traditional nuclear power management systems however we must consider chernobyl was considered safe no matter what due to the fail safe system they had in place. A great program was recently released which showed how out of depth they really were and this start up in Boston that claims to have all the answers and the only missing puzzle piece is actually building it has no track record. Therefore despite the claims of nuclear fusion being the future we have to consider how far and how many hurdles we are yet to hit.

Despite the lack of experience lets assume that all goes well and nuclear fusion becomes a thing. How accessible will this be to the public? Do we really believe energy companies will be providing cheap energy via nuclear fusion or will this still be reserved for the elite very much like quantum computers?

We also have to consider the moral obligations and the public viewpoint of nuclear power. At the moment there are multiple different organizations which are trying to combat the development of nuclear power plans and which could put a halt to nuclear fusion. I'm actually for the development of nuclear energy and providing a more efficient energy system but I can understand the concerns about accidents and management of waste and how it can literally destroy the environment it is in.

In conclusion even if nuclear fusion becomes a thing in the next few years and quantum computers could be cooled at the temperature required at a decent price I highly doubt that other than the wealthy elite the power of nuclear energy will not be easily accessible.

[UnruffledST]

Didnt bother to read all the replies but seriously you think Bitcoin has a option at the moment to really implement quantum resistant cryptography? Bitcoin beings so slow, would we even slower due to transactions taking lonher to verify due to the complexity in confirming such transactions.

[AverageGlabella]

Didnt bother to read all the replies but seriously you think Bitcoin has a option at the moment to really implement quantum resistant cryptography? Bitcoin beings so slow, would we even slower due to transactions taking lonher to verify due to the complexity in confirming such transactions.

That's the point of reading all the replies. This not a discussion about quantum computers becoming a problem currently but in the future and how we would deal with that. We have touched upon why it hasn't been implemented currently a few times in the discussion and although you do bring up a point of making Bitcoin unnecessarily slow right now in the future it is something that will have to happen if we ever do reach the point of a 2000+ qubit quantum computer or whatever would be the required amount to become a serious threat to the algorithm.

[TimeBits]

Decided to move this to serious discussion considering the lack of activity on Bitcoin Discussion I'm interested in hearing others opinions on the quantum computers currently and what they will be like in the future.

Anything compiled using AES is already crackable with the computers we have today, When satoshi created bitcoin he did not know wtf a Asic was, he Had no clue asics would come into existence. Wait till asic2.0`s come online. They will be able to crack AES even easier. There will be a single chip made that has more hashing power than all of the bitcoin farms combined in the next 20 years.

[arcmetal]

Didnt bother to read all the replies but seriously you think Bitcoin has a option at the moment to really implement quantum resistant cryptography? Bitcoin beings so slow, would we even slower due to transactions taking lonher to verify due to the complexity in confirming such transactions.

That's the point of reading all the replies. This not a discussion about quantum computers becoming a problem currently but in the future and how we would deal with that. We have touched upon why it hasn't been implemented currently a few times in the discussion and although you do bring up a point of making Bitcoin unnecessarily slow right now in the future it is something that will have to happen if we ever do reach the point of a 2000+ qubit quantum computer or whatever would be the required amount to become a serious threat to the algorithm.

Quite correct AverageGlabella.  Concerning whether adding more complexity to bitcoin's code would slow it down in the future: I hate to state the obvious but, whatever. In the future, if or when it is necessary to add more code, the hardware in general will be orders of magnitudes faster.  That is, processing and therefore communications will be much faster, and so increasing the amount of code necessary to complete a transaction will be of no consequence.  It is difficult for humans to discern the difference between 10 nanoseconds and 100 nanoseconds, adding more code will not be noticed with much faster hardware.

[arcmetal]

I suppose the final question that sits beneath everything else is: is self-consciousness itself an emergent behaviour? I'm still unsure about the singularity, I take your point, but I won't dismiss it completely until this question has a definitive answer. Stuff that seems magical fantasy today could be mundane and commonplace to the AIs of the future.

The problem is that we are extremely far from understanding how our brains function.  So far in fact from knowing, that we could be thousands of years or maybe millions of years from this type of understanding.  We just don't know how much we don't know.

Take for example, having read recently that they have discovered tiny tubules at the ends of dendrites.  They suspect that besides transferring chemicals and electrical impulses at the synapses, we may also be transmitting bits of light (some call it photons) across that junction.  This could mean that our brains are actually photonic in nature.  This is what I mean by "we have no clue".

We can't replicate it or build it into a machine until we have a full understanding of it.

It is still fun to ponder what self-consciousness might be, but to say we can build a machine to mimic this, or that one of our machines will happen upon it one day is just silly.

[myternity]

Hello everybody. Nice to meet so many people interested in quantum threat to a blockchain in one place. We've been working on one post-quantum project for 2 years and of course we're talking with physicists, pq-cryptographers and other academic minds. And I just want to add a couple things and links you guys might like.
 
First — probably you will be interested in reading about Neven's law (https://www.quantamagazine.org/does-nevens-law-describe-quantum-computings-rise-20190618/). It is not a "law" of course but an interesting thing to keep in mind.
Second — the most powerful quantum chip for today is 128-qubit chip produced by Rigetti (https://medium.com/rigetti/the-rigetti-128-qubit-chip-and-what-it-means-for-quantum-df757d1b71ea).
Third — how many quits you need to crack a blockchain. It depends on a type of encryption, but the point is, it is 2300+ (https://en.wikipedia.org/wiki/Elliptic-curve_cryptography#Quantum_computing_attacks)
Fourth — Intel thinks we'll get 1000 quits by 2024 (https://spectrum.ieee.org/nanoclast/computing/hardware/intels-new-path-to-quantum-computing) and ECDSA will be at risk by 2027 (https://arxiv.org/pdf/1710.10377.pdf).
Fifth — implement post-quantum encryption to existing blockchains? This is a close to impossible task.
Sixth — That's what NIST says about PQC in their project (probably all of you aware of it but https://csrc.nist.gov/Projects/Post-Quantum-Cryptography):

Historically, it has taken almost two decades to deploy our modern public key cryptography infrastructure.  Therefore, regardless of whether we can estimate the exact time of the arrival of the quantum computing era, we must begin now to prepare our information security systems to be able to resist quantum computing.

So, yes, quantum threat is a thing to be aware (and probably afraid of) and yes, we gotta start working on it now. Plus, thanks to smart people from NIST we're in good hands. Btw we're working on a utility to secure all of the blockchains from it. I hope this week we'll publish an article about quantum thief where we will explain why the only thing that will save us from it is game theory (and PQC, of course).

I hope I didn't miss anything. Will be happy to answer your questions (but I can get here only a couple times per week max so don't wait for fast replies, sorry)

[TheWolf666]

Quantum computers are not going to replace the computers as we know them. They can be considered like a GPU that will be attached to a normal computer, providing speed for some limited operations. Their usage will be very limited specially at the beginning and their price very high.

[Macadonian]

Hello everybody. Nice to meet so many people interested in quantum threat to a blockchain in one place. We've been working on one post-quantum project for 2 years and of course we're talking with physicists, pq-cryptographers and other academic minds. And I just want to add a couple things and links you guys might like.
 
First — probably you will be interested in reading about Neven's law (https://www.quantamagazine.org/does-nevens-law-describe-quantum-computings-rise-20190618/). It is not a "law" of course but an interesting thing to keep in mind.
Second — the most powerful quantum chip for today is 128-qubit chip produced by Rigetti (https://medium.com/rigetti/the-rigetti-128-qubit-chip-and-what-it-means-for-quantum-df757d1b71ea).
Third — how many quits you need to crack a blockchain. It depends on a type of encryption, but the point is, it is 2300+ (https://en.wikipedia.org/wiki/Elliptic-curve_cryptography#Quantum_computing_attacks)
Fourth — Intel thinks we'll get 1000 quits by 2024 (https://spectrum.ieee.org/nanoclast/computing/hardware/intels-new-path-to-quantum-computing) and ECDSA will be at risk by 2027 (https://arxiv.org/pdf/1710.10377.pdf).
Fifth — implement post-quantum encryption to existing blockchains? This is a close to impossible task.
Sixth — That's what NIST says about PQC in their project (probably all of you aware of it but https://csrc.nist.gov/Projects/Post-Quantum-Cryptography):

Historically, it has taken almost two decades to deploy our modern public key cryptography infrastructure.  Therefore, regardless of whether we can estimate the exact time of the arrival of the quantum computing era, we must begin now to prepare our information security systems to be able to resist quantum computing.

So, yes, quantum threat is a thing to be aware (and probably afraid of) and yes, we gotta start working on it now. Plus, thanks to smart people from NIST we're in good hands. Btw we're working on a utility to secure all of the blockchains from it. I hope this week we'll publish an article about quantum thief where we will explain why the only thing that will save us from it is game theory (and PQC, of course).

I hope I didn't miss anything. Will be happy to answer your questions (but I can get here only a couple times per week max so don't wait for fast replies, sorry)

I'm interested on your take on your 5th point. Its quite a bold claim that has been disputed over in the development sub forum and here by some pretty bright minds. Why do you think its an impossible task? I think its difficult for a number of reasons including but not limited to the consumer issues that would come with bigger such a big change. As far as I know there are many different projects working on including quantum resistant algorithms into the existing infrastructure of Bitcoin and they are making good progress. The only issue with that is this would require a hard fork and there will be multiple different options to choose from. I would be interested in getting achows opinion on the matter but I'm afraid that discussion about quantum computers would quickly get buried.

[myternity]

I'm interested on your take on your 5th point. Its quite a bold claim that has been disputed over in the development sub forum and here by some pretty bright minds. Why do you think its an impossible task? I think its difficult for a number of reasons including but not limited to the consumer issues that would come with bigger such a big change. As far as I know there are many different projects working on including quantum resistant algorithms into the existing infrastructure of Bitcoin and they are making good progress. The only issue with that is this would require a hard fork and there will be multiple different options to choose from. I would be interested in getting achows opinion on the matter but I'm afraid that discussion about quantum computers would quickly get buried.

Yes, I should've probably disclose in more details.
When we say "it is quantum safe signature" we imply "it is probably quantum safe signature" due to the fact that someone had already mentioned in this thread, we don't have a quantum computer yet. What we need here is a solution with an encryption variability to have the opportunity to transfer new keys for the analogues of old addresses after hard fork. If we won't have this feature we'll have to make multiple hard forks with every "new" quantum computer. Another reason is a performance decline because a lot of PQ sigs are "heavier". Everybody are waiting for NIST PQC results. Actually this is what one of our products is about and this is one point of the articles. So it is difficult as a one time task but if you do it several times it requires an architecture rebuilt to make it easy and reliable. Plus we're talking not only Bitcoin but any other blockchain.
So it is an issue.

[PrimeNumber7]

The reason why I'm concentrating on the operating costs and the logistics of running something capable of breaking algorithms is that even if a quantum computer was theoretically released tomorrow with the required amount of qubits to breach algorithms it would still only limited to a few individuals which might not have any malicious intent meaning it might not even be a threat anyway.

I speculate, most likely it will be a government - one of the five eyes, or China - or an entity that is a de-facto arm of a government, and I think they will absolutely be a malicious actor. It will be in this entity's interest to keep the fact they have the QC technology sufficient to break ECDSA and other encryption algorithms a state secret because it will allow their government to spy on their enemies for longer.

If a government develops QC technology that can be run efficiently, and use said technology to steal a few hundred thousand bitcoins, the coin they steal would be worth billions as of when they steal the coin, but its value would quickly plummet once many people start complaining their coin was stolen after practicing good security practices. It would also be a warning to other governments, banks, communications companies, and others to upgrade their encryption systems ASAP, and to stop using "now broken" encryption systems immediately, even if this means taking services offline for some time.

If a government were to develop QC tech that can efficiently break modern encryption algorithms, I think they would prefer to use it to decrypt intercepted communications via the internet and elsewhere, with the hope their enemies will continue using "broken" encryption algorithms. Last month, a bunch of European internet traffic was rerouted via China for two hours, and there have been similar incidents before. These incidents could be true errors, or they could have been the Chinese government collecting encrypted internet traffic hoping to decrypt it, with current or future technology.

[Cnut237]

Nuclear fusion [...] theoretically its safer than other traditional nuclear power management systems however we must consider chernobyl was considered safe

We also have to consider the moral obligations and the public viewpoint of nuclear power. [...]  I can understand the concerns about accidents and management of waste and how it can literally destroy the environment it is in.

Fusion is an entirely different process to traditional nuclear power - in fact it's the exact opposite. It doesn't use radioactive decay at all.

Nuclear power as we know it today is produced by fission. Essentially fission is where heavy atoms (uranium) are bombarded by neutrons, which causes them to split and release energy. The neutrons that come out of this fission then hit other heavy atoms and can cause a chain reaction. It can be a runaway process, and controlling it is kind of analogous to a brake pedal - someone at the plant always has their foot on this metaphorical pedal in order to keep the reactions under control. There are obviously a lot of dangerous by-products, partly the leftover split atoms, but also (more dangerous) heavy atoms that absorb neutrons but don't split, and can become some nasty forms of plutonium.

Fusion is the opposite. This is where light atoms (hydrogen isotopes) are fused together to form helium, neutrons and vast amounts of energy - a lot more than fission. Two further benefits are that a) there is no dangerous waste as both the source materials and the waste products (helium plus neutrons) are non-radioactive, and b) there is no danger of an uncontrollable chain reaction because fusion relies on the continuous input of power, if the power stops then the reaction cools and stops.

Do we really believe energy companies will be providing cheap energy via nuclear fusion

Not sure about this one. In theory if fusion becomes straightforward and it's an open marketplace, then companies will compete to drive the price down. If it's all state-controlled or a monopoly though, who knows...

[Cnut237]

Quantum computers are not going to replace the computers as we know them. They can be considered like a GPU that will be attached to a normal computer, providing speed for some limited operations. Their usage will be very limited specially at the beginning and their price very high.

I agree that quantum computing doesn't offer an advantage in every situation. I think there is often a perception that quantum computers are just faster than conventional computers, but that's not really the case. Where they excel is in dealing with extremely complex problems. The advantage of a quantum computer is that the complexity scales differently.

A conventional computer can solve a problem 'x' in 'y' seconds, taking 'z' number of steps.
If you build a faster conventional computer, it can maybe solve problem 'x' in 'y/2' seconds, so twice as fast - but it will still take 'z' number of computational steps to do so.
The advantage of a quantum computer is that it can drastically reduce 'z', the number of steps required. This is why they are 'faster'.

It's quite fascinating when you get into it. If you are interested, have a look at Grover's algorithm.

[arcmetal]

Do we really believe energy companies will be providing cheap energy via nuclear fusion

Not sure about this one. In theory if fusion becomes straightforward and it's an open marketplace, then companies will compete to drive the price down. If it's all state-controlled or a monopoly though, who knows...

The problem has always simply been that power generation is centralized, concentrated in a few hands.  Large power plants producing it, and large elaborate distribution lines to deliver it.  This is not how it could have been, but a few decided it should be this way, for obvious reasons, for the sake of profit.

But things have been slowly changing since solar panels have been mass produced, getting cheaper, and gaining in efficiencies.  With decentralized power ( ... decentralized, funny aye  )  there would be no need for large power plants or expansive distribution networks.  At worst there may still be a need for small local power distribution centers for emergencies, but nothing more.  ... The cost would solely be the production, and installation of the solar panel hardware, and the energy free.  There has always been animosity from those that wish to profit from centralized power, and this will continue until the end.  The end being fully decentralized power.

Throughout history energy has been commoditized, but in this modern age this is no longer necessary.   In this universe, besides space and time, energy is the most abundant thing.  The water we drink, or the oxygen we breathe is far more rare than energy, and yet we pay each month for power.

Nuclear power, fission or fusion, when developed enough, and made small enough will be useful for areas that have little to no access to the sun.  Like maybe Pluto.     Or, interstellar travel.

I don't see free power as a threat to bitcoin.  Free power may seem to make the cost of producing btc less, but then any extra cash a miner has would be used for more mining hardware, increasing btc's difficulty, which increases its cost of production, which helps to increase its price, and so on.  

[michellee]

I don't make a research about quantum computing and I don't have any knowledge about that, I only user but I know a little about computer. My opinion, no matter if there are the newest computer design or technology, it will not threaten bitcoin but it will support the network so bitcoin or cryptocurrency could grow more than we thought.

Maybe the newest computer will solve the calculation of bitcoin mining so it could break every problem in the bitcoin mining. Like what we see on the bitcoin mining process, we see the newest GPU release and help the mining process. That will happen too with the quantum computing so it will support and help cryptocurrency.

[Macadonian]

Maybe the newest computer will solve the calculation of bitcoin mining so it could break every problem in the bitcoin mining. Like what we see on the bitcoin mining process, we see the newest GPU release and help the mining process. That will happen too with the quantum computing so it will support and help cryptocurrency.

This is not how quantum computers work however if this was possible then this would be very bad for Bitcoin. The difficulty would have to increase so much that it would outprice almost everyone out of the market meaning only those that can afford the hashrate of these "super computers" that the general consumer would not be able to mine new Bitcoin. Bitcoin would become a currency only used by the very wealthy elite of the world. Luckily quantum computers aren't going to be useful for mining and are currently only good for solving problems using factoring. Which means they will be very good at certain things but overall not that good even for a personal computer. They are very good at cracking algorithms especially the one that Bitcoin is currently using.

[Macadonian]

The problem has always simply been that power generation is centralized, concentrated in a few hands.  Large power plants producing it, and large elaborate distribution lines to deliver it.  This is not how it could have been, but a few decided it should be this way, for obvious reasons, for the sake of profit.

But things have been slowly changing since solar panels have been mass produced, getting cheaper, and gaining in efficiencies.  With decentralized power ( ... decentralized, funny aye  )  there would be no need for large power plants or expansive distribution networks.  At worst there may still be a need for small local power distribution centers for emergencies, but nothing more.  ... The cost would solely be the production, and installation of the solar panel hardware, and the energy free.  There has always been animosity from those that wish to profit from centralized power, and this will continue until the end.  The end being fully decentralized power.

Throughout history energy has been commoditized, but in this modern age this is no longer necessary.   In this universe, besides space and time, energy is the most abundant thing.  The water we drink, or the oxygen we breathe is far more rare than energy, and yet we pay each month for power.

Nuclear power, fission or fusion, when developed enough, and made small enough will be useful for areas that have little to no access to the sun.  Like maybe Pluto.     Or, interstellar travel.

I don't see free power as a threat to bitcoin.  Free power may seem to make the cost of producing btc less, but then any extra cash a miner has would be used for more mining hardware, increasing btc's difficulty, which increases its cost of production, which helps to increase its price, and so on.  

Although most countries charge for power they also charge for water and can sometimes be very expensive depending on the country that you live in. I would essentially agree with most of your points other than the statement that bigger and more industrialized power plants won't be needed when we are relating it back to quantum computers. In general life I would agree but when providing the energy necessary to house a quantum computer and run it at its most efficient conditions this would probably not be sufficient with solar panels or would be a logistical nightmare.  Nuclear fusion will probably be used but as you touched upon this will be in the hands of the few and I don't think a cheap and efficient solution like nuclear fusion (in theory) will be distributed to the masses. This will probably be something which is exclusive to governments and I can see them justifying this by stating that nuclear fusion is dangerous and is frowned upon by most of the world however they need to have emergency fail safes in place just in case their country goes without power. Playing on peoples heartstrings about keeping hospitals running and saving lives and that will be the only reason I can see nuclear fusion being first of all accepted by the community and secondly developed by the government. They'll use it for emergencies and military operations only. However who's not to say that they won't run their quantum computers off of this energy and deem it military operations. After all factoring could break many different algorithms and they could potentially get intel from their enemies. Bitcoin will probably be an enemy to the governments and who's to say they won't try attacking it. This is all based on assumption and is all theoretically however I do like to imagine the sort of power which would come with quantum computers running on nuclear fusion. Luckily the masses won't have access to both of these technologies and only governments and possibly the wealthy elite will which means there aren't too many potential attackers to the current algorithm that Bitcoin uses. Which probably means that we have an increased amount of time to figure out the steps in protecting against quantum computers.

Quantum computers are not going to replace the computers as we know them. They can be considered like a GPU that will be attached to a normal computer, providing speed for some limited operations. Their usage will be very limited specially at the beginning and their price very high.

I agree that quantum computing doesn't offer an advantage in every situation. I think there is often a perception that quantum computers are just faster than conventional computers, but that's not really the case. Where they excel is in dealing with extremely complex problems. The advantage of a quantum computer is that the complexity scales differently.

A conventional computer can solve a problem 'x' in 'y' seconds, taking 'z' number of steps.
If you build a faster conventional computer, it can maybe solve problem 'x' in 'y/2' seconds, so twice as fast - but it will still take 'z' number of computational steps to do so.
The advantage of a quantum computer is that it can drastically reduce 'z', the number of steps required. This is why they are 'faster'.

It's quite fascinating when you get into it. If you are interested, have a look at Grover's algorithm.

I have mentioned in a couple of my replies that quantum computers are exceptional at only certain tasks but actually quite lackluster in other areas. They are not personal computers and wouldn't be useful to the majority of people. However those that are looking to crack currently used algorithms and via using the quantum computers exceptional talent at factoring they are very useful. Even if quantum computers became available to the masses it just wouldn't appeal to them. I don't have any interest in cracking algorithms for an example but militaries and governments probably do. Enemies to Bitcoin probably do.

I speculate, most likely it will be a government - one of the five eyes, or China - or an entity that is a de-facto arm of a government, and I think they will absolutely be a malicious actor. It will be in this entity's interest to keep the fact they have the QC technology sufficient to break ECDSA and other encryption algorithms a state secret because it will allow their government to spy on their enemies for longer.

If a government develops QC technology that can be run efficiently, and use said technology to steal a few hundred thousand bitcoins, the coin they steal would be worth billions as of when they steal the coin, but its value would quickly plummet once many people start complaining their coin was stolen after practicing good security practices. It would also be a warning to other governments, banks, communications companies, and others to upgrade their encryption systems ASAP, and to stop using "now broken" encryption systems immediately, even if this means taking services offline for some time.

If a government were to develop QC tech that can efficiently break modern encryption algorithms, I think they would prefer to use it to decrypt intercepted communications via the internet and elsewhere, with the hope their enemies will continue using "broken" encryption algorithms. Last month, a bunch of European internet traffic was rerouted via China for two hours, and there have been similar incidents before. These incidents could be true errors, or they could have been the Chinese government collecting encrypted internet traffic hoping to decrypt it, with current or future technology.

There are currently a number of different countries and governments which are extremely hostile to Bitcoin and others which aren't sure what to do in terms of banning it or allowing the people to use it. China is a scary one due to their history of not caring what others think and how they severely limit and censor their population. You make a excellent point that anyone with a quantum computer capable of breaking algorithms will probably not do it on a mass scale and will probably make targeted attacks to prevent everyone switching over to a quantum resistant algorithm.

[Cnut237]

The water we drink, or the oxygen we breathe is far more rare than energy, and yet we pay each month for power.

Although most countries charge for power they also charge for water and can sometimes be very expensive depending on the country that you live in.

Given the ever-increasing effects of climate change, I think it's likely that access to water will be a huge issue as this century progresses. Wars might even start over it. You look at somewhere like Egypt and wonder what would happen if some of the countries upstream started using or diverting more from the Nile, particularly as they grow in population. You look at China and the effort it puts into acquiring and holding Tibet - which is the source of the biggest Chinese rivers - and you wonder what would happen if India, also growing in population, decides it needs more of that Tibetan water...

I don't think a cheap and efficient solution like nuclear fusion (in theory) will be distributed to the masses. This will probably be something which is exclusive to governments

If commercial fusion power does become possible, then maybe it will be used to resolve the issue of water shortage by providing cheap green power for water desalination plants... These plants already contribute to global warming, and likely will make the problem even worse as they expand in use due to water shortages. So with the way the world is going, if fusion does become possible, I'm not sure governments will be able to hold it back for themselves or even charge excessively for it - as energy demands and resource demands increase, providing access to fusion power may be one of the only ways to avert war.

[Saidasun]

Bare with me with this reply has I've been working on it for a while and have dropped it and came back to it a few times over the last few days. Its also taken me a while to get this all down. This discussion actually prompted me to log in to the forum after a while because this quality discussion is a rarity these days on this forum.

What I want to address is the different types of solutions which are currently either being developed or are fully developed and been deployed elsewhere. First I'll talk about the quantum resistant ledger and why Bitcoin doesn't need this and in fact I prefer the way Bitcoin is dealing with the whole quantum computer threat. Lets be clear and say quantum computers actually already exist and are already being used for multiple different things other than cracking algorithms and encryption. However just like its been discussed in this thread quantum computers are a number of years from becoming good enough to be able to threaten most encryption and certainly Bitcoins method of encryption. Estimations by large companies within the field has predicted we'll be seeing quantum computers with 2500+ qubits by the year 2025 but like many of you said these will be only just developed and will require a lot of testing and certainly won't be available to the average joe. However just because the mass population doesn't have access to these superior quantum computers doesn't mean its still not a threat. Governments which are probably funding these quantum computers are known to be pretty hostile towards Bitcoin and could use this to their advantage along with other things on their agenda. What some altcoins have done is included a quantum resistant ledger right from the get go in order to try and appeal to those that are misinformed. Implementing a quantum resistant ledger is all good when the altcoin its protecting is only worth a few cents but imagine implementing a untested and most importantly unproved quantum resistant ledger in a multi million pound industry like Bitcoin. This is the reason why Bitcoin developers and us as users of the software should be encouraging the development of Bitcoin to thoroughly test anything before its added to the "mainframe". The quantum resistant ledger I'm talking about has been implemented by a number of different altcoins but we are still unsure whether they will be ready and scalable without causing too much disruption to the value and of its users. This is why Bitcoin is one of the more respected cryptocurrencies out there because everything which is implemented is thoroughly tested and isn't just trying to appeal to people with new sparkly features. The quantum resistant ledger for example is a complete waste of time right now and isn't much more than a gimmick. It doesn't provide any more level of security than Bitcoin does and when quantum computers are able to break the algorithm Bitcoin uses it will then switch to a quantum resistant one which could in fact be better than the current quantum resistant ledgers we are seeing because its been tested over a number of years instead of just developed and thrown in there even when its not needed.

Despite these quantum resistant ledgers being gimmicks currently because they aren't providing any more security than traditional cryptocurrencies its at least a good idea to provide proof of concepts to the developers of Bitcoin and they can improve on the existing quantum resistant algorithms.The current quantum resistant solutions out there are mostly using eXtended Merkle Signature Scheme a hash-based digital signature system which allows reusable addresses and this is where I think Bitcoin could implement a less invasive algorithm onto the network. The problem with reusing addresses is once they have broadcast themselves onto the network they are then vulnerable to an attack from a quantum computer because they have exposed their public keys onto the network. This hash would then be suspect to quantum computers by using factoring to break the encryption and this is where I think the network could be improved without implementing a fully quantum resistant ledger by only allowing the use of an address once. So you could receive x amount on one address and then the wallet software automatically assigns that to a different address without broadcasting it to the network. I think this is possible and should be the only time an amount isn't broadcast to the network or only allow addresses to be used once by allowing them to receive coin and send from it once this would reduce the probability of a quantum computer finding the public key and attempting to crack it. We could actually do this in the current implementation of Bitcoin but not many people do and they simply reuse addresses even when its recommended to only use addresses once to avoid privacy issues. However if this was fully implemented into the network as a standard I think that would solve most of the problems. Its not completely safe but doesn't have a massive impact like implementing an entire new algorithm. At least for now we all know that Bitcoin will eventually have to adopt a new algorithm to keep up with the hardware being developed but so will many other things in the world.

Secondly lets talk about factoring and how quantum computers actually do it because I've seen this mentioned in a few of the replies but none of them have really gone into enough depth to justify mentioning it. So quantum computers are exceptionally fast at a few things and one of them is factoring. Factoring is used to crack conventional cryptography and this will be the route that quantum computers will take if they were to ever break the algorithm of Bitcoin but just mentioning factoring isn't really explaining how quantum computers are exceptionally good at it. Well quantum computers are very good at solving Discrete Fourier transform which in mathematics is converting a finite sequence of equally spaced samples of a function into a same the exact same length sequence of equally spaced samples of the discrete time Fourier transform which is a complex valued frequency. Discrete time Fourier transform is used to analyze samples of a continuous function. Discrete time is called that because it handles discrete data which their intervals are units of time basically. So using these functions quantum computers factor against the algorithm to find the solution. We have probably studied factoring at one point in our lives which includes multiplication however the factoring that quantum computers are doing is on a completely new level to that. Here's an example of a factoring problem:

The folllowing factoring problem

Code:

Given a number $N = pq$ where $p,q$ are primes, how do you recover $p$ and $q$?

would be solved by comparing common factors and using multiplication groups There's a great explanation already out there which outlines this problem and provides the sequence of the process to determine the solution: https://quantumcomputing.stackexchange.com/questions/1383/what-makes-quantum-computers-so-good-at-computing-prime-factors

By increasing the amount of qubits a quantum computer has we are effectively making it quicker at solving these problems by using the above mentioned method. This process is a lengthy one using current modern day computers but the idea behind quantum computers is once they have hit 3000 qubits they will be able to break most current day algorithms within a matter of seconds.

[Macadonian]

Given the ever-increasing effects of climate change, I think it's likely that access to water will be a huge issue as this century progresses. Wars might even start over it. You look at somewhere like Egypt and wonder what would happen if some of the countries upstream started using or diverting more from the Nile, particularly as they grow in population. You look at China and the effort it puts into acquiring and holding Tibet - which is the source of the biggest Chinese rivers - and you wonder what would happen if India, also growing in population, decides it needs more of that Tibetan water...

If commercial fusion power does become possible, then maybe it will be used to resolve the issue of water shortage by providing cheap green power for water desalination plants... These plants already contribute to global warming, and likely will make the problem even worse as they expand in use due to water shortages. So with the way the world is going, if fusion does become possible, I'm not sure governments will be able to hold it back for themselves or even charge excessively for it - as energy demands and resource demands increase, providing access to fusion power may be one of the only ways to avert war.

Water is a big problem and whats worrying is most of the water around the world is privately owned and if a water were to break out these private companies could be bought out in an attempt to harm the civilians and cause unrest in that country. I might actually start a thread about water consumption and the worries if a war broke out but at the moment I'll continue discussing the quantum computers as this is possibly some of the best discussion I have participated in relating to it.

Bare with me with this reply has I've been working on it for a while and have dropped it and came back to it a few times over the last few days. Its also taken me a while to get this all down. This discussion actually prompted me to log in to the forum after a while because this quality discussion is a rarity these days on this forum.

Holy crap! I did not know we had this many people who are knowledgeable in the quantum mechanics field and can discuss quantum computers in such depth. I'll admit that what you have mentioned about factoring and how its actually done is a little over my head currently as I'm only dipping my toes into quantum computers. My knowledge is limited by I know what factoring is and I know quantum computers are exceptionally good at it but that actual specifics of working it out is still gibberish to me but I appreciate the input on the actual solutions and working it out!

The quantum resistant ledger has been running roughly a year and AFAIK as received some excellent praise and has received a lot of media coverage because of that although your point about reusing addresses wouldn't be sufficient in my opinion because we are then relying on the chance of the address not being targeted rather than implementing a system which is completely quantum resistant. It is true that the less you reuse an address the less exposure it has on the public ledger and thus the less likely it is to be a target although this doesn't completely prevent the address from being targeted due to it still being recorded on the address once they receive an amount. By implementing a quantum resistant algorithm we at least prevent this sort of attack from happening and there is no risk whatsoever although I would agree that reusable addresses shouldn't be a thing and you should only be able to use new addresses every time for other privacy issues but the way its implemented into the blockchain right now is the user gets to decide what sort of piracy level they are comfortable with which could possibly be the best approach if we are to stick with the decentralized way of Bitcoin and not limit users of it to specific rules.