Bitcoin Forum

There's a couple of interesting white papers to read:

https://arqit-res.cloudinary.com/image/upload/v1627024109/Assessment_of_Quantum_Threat_To_Bitcoin_and_Derives_Cyrptocurrencies_nrp6iq.pdf

https://arqit-res.cloudinary.com/image/upload/v1627369111/Digital_assets_The_security_problem__yya4bn.pdf


So Quantum Computers will be available to buy in the shops in lets say 10 years time from now and 5 years from now the first commercial business grade quantum computers will be available for sale for businesses.

Quantum computers can get anyone's private keys in fraction of a second.

The few quantum computers in the world today owned by the Big tech giants such as google, Microsoft, even china has one is used to harvest all that data from billions of people to a single point Ai. These quantum computers are massive, require a lot of cooling and are power hungry that require nuclear reactors to run them. But these are the 1st generation quantum computers.

Eventually these quantum computers will get smaller, more efficient to run off the electricity in your home and everyone will have quantum computer in their bedrooms when they hit the shelves in shops or on Amazon online in 10 years time but at a crazy price tag so not everyone can afford one in 10 years time but they will get cheaper and become mainstream especially with gamers for obvious reasons. Playing fortnite at crazy 16k resolution at million frames per second.

So how can Bitcoin survive in this technological quantum era? The B in Bitcoin stands for Bits. Quantum computing is Qubits meaning it can be a binary 1 or 0 at the same time similarly like a light switch being on or off at the same time that sounds crazy and impossible.

Will there be Qitcoin or somewhat?

No, they can't.

Quantum computers can exponentially speed up solving the discrete logarithm problem, but can only linearly speed up finding a collision for a hash. What this means in practice is that they are only useful for brute forcing private keys in which the attacker knows the public key. Given that you public key is only revealed when you make a transaction, sign a message, or otherwise choose to share it, then if you only ever send bitcoin to brand new addresses which you never reuse and never share the public key of, then your bitcoin is 100% safe. A quantum attacker cannot obtain a private key only from knowledge of the address.

Further, quantum computers aren't an "all or nothing" thing. Sure, the first quantum computer might hit the market in a decade, but it will be inefficient and have a very small number of qubits. It would still take thousands of years to crack a single private key. It will be centuries before quantum computers reach the stage that they can reverse a public key to a private key in a "fraction of a second".

At some point, bitcoin will fork to a quantum resistant algorithm.

More bits will simply be added to new keys.
How many more bits will depend on the strength of the quantum computers.
Addresses will have to update before old ones are crack (still a big if).
Hopefully this will happen slowly enough so that individuals can update their addresses.
Satoshi's coins would though possibly be cracked, and perhaps we will learn more about the identity of SN.

I've never understood the hype around quantum computers. Isn't it just a move back to analog, with a fancy new term?
The problem doesn't change much for much more powerful computers, quantum or otherwise.

It is fascinating. I am glad you posted this, because I was about to post a thread on this. Had not heard about the threat to crypto from quantum computers in probably a decade, but quantum technology seems to be making major(?) breakthroughs, recently.

Google recently announced they had developed "time crystals (https://www.zdnet.com/article/google-says-it-has-created-a-time-crystal-in-a-quantum-computer-and-its-weirder-than-you-can-imagine/?ftag=COS-05-10aaa0h&utm_campaign=trueAnthem%3A%20Trending%20Content&utm_medium=trueAnthem&utm_source=facebook&fbclid=IwAR1K9J_yirybXpvoz-gZxU_V9ALTx6-g5MFE3AZli90cq9sz4q9Jal9Hruc)," which from my dumbed down interpretation are basically quantum transistors. The problem with quantum computers is that their current "transistors" decay rapidly, are hard to manufacturer and have to be replaced frequently. Time crystals solve both of these problems and potentially make quantum computers a reality. (Don't be evil) Google is the LAST company I would want making these discoveries.

Then again, they have been talking about quantum computing probably before I was born, so who knows how close they really are. But the concern is real if governments were able to develop these machines or have already done so.

China already has a quantum computer? (https://www.express.co.uk/finance/city/1476687/bitcoin-price-latest-ethereum-crypto-quantum-computing-threat-encryption-cryptographic-sec)

The good news is, encryption can and will evolve.

Good to know. What about the hashing algorithm itself? Could it hijack mining?

The general topic of quantum computers as a potential threat to Bitcoin and other cryptocurrencies has been discussed many times here. Nobody knows for sure how that technology is going to develop and whether it will go significantly beyond what we already have. To make cryptos obsolete, we need a breakthrough in quantum computing, and so far, the topic has been around for years without breakthroughs. When the technology is at early stages, it's really hard to predict if it thrives in the future. When people landed on the Moon in 60s, tourism to planets of the Solar system by the end of the 20th century sounded like a very realistic prediction. And yet, here we are 60 years later, still only being able to go into space and to land of the Moon at best. What I'm saying is that maybe the threat of quantum computers to cryptos will remain the same in 60 years, too.

I don't know if an industrial or a space mission scale of a quantum computer is going to be commercially available for that span of time, yes it's possible that it will be available but I don't think it will be the end for crypto because I am sure that most commercially available is probably going to overheat really fast. Plus, quantum computers are so sensitive and they're the size of a room so it's still impossible to see it really commercially available, maybe a rich person can afford one.

No, they won't be.

A quantum computer doesn't just perform the same calculations faster than a regular computer. Rather, depending on the problem it is solving, it can use different processes or algorithms altogether. Instead of it taking an exponential number of operations to reverse a public key to a private key (2^x, where x is the number of bits), it only takes in the order of x³. Moving from 128 bits to 129 bits for regular computer adds another 3.4*10³⁸ operations, but for a quantum computer, only adds another 49,547 operations, which is trivial. It's not simply a case of adding more bits - it requires a fork to a different algorithm altogether.

It is likely that at some point in the future, quantum computers will become more energy efficient and cheaper than ASICs when it comes to mining. This will not be a sudden event, but rather a gradual process, just as the move from GPUs to ASICs was not a sudden event. Just as the owner of the first ASICs couldn't suddenly mount a 51% attack, neither will the owner of the first quantum computers designed for mining.

If a Quantum computer could do that without the owner's knowledge, then it's pretty clear that the former would be blamed for inventing the production themselves, since at least they've included scripts hoping for data storage. It would be very dangerous, for its users. So far we haven't come across any complaints that went viral enough when shoppers lost some of their data after using a Quantum computer.

First, this issue has been discussed several time on this forum and what I see is that people hype this Quantum computer than its capacity. However, it will take about a thousand or hundred years before Quantum computers that stand a chance to get wallet private keys will be develop, and even if it develops it's still not a threat to Bitcoin and it can't also break the SHA512 which Bitcoin use but it can only derive wallet private keys through an exposed public key.

Oh boy it's one more of those quantum computers doomsday thread...  ::)

Who told you that? TV or CNN?
If that is true, all those lost coins private keys would be cracked and sold by now, and that didn't happen.
Quantum computers will be limited doing only one function and by the time they become mainstream, everything will be cracked not just Bitcoin, that means all bank and military security.

Same way like all other encryption related tech we use today.
I guess it will be one more ''death'' of Bitcoins for mainstream media...

No, but there are already some shitcoins that are ''quantum resistant''.

Nontechnical people are reacting like that quantum computer has the superpower to go to people's houses, and will steal their cold storage/physical wallets.
They are so concerned about 256 bits Bitcoin private keys as if 4 digit atm PIN and bank card PIN are irresistible. ::) The algorithm system used in Bitcoin, "ECDSA" is also used to secure the Fb, Twitter, Email, and other messaging apps. No one is talking about that but everyone is so much concerned about Bitcoin.
Another thing is, SHA-256 algorithm is theorized to be quantum-resistant, where Bitcoin is using SHA-512 further secured than SHA-256.

Nope, I don't think so. We are at a stage in quantum computing where it's still experimental and the size of one quantum computer is the same size as old computers back then which is worth a room. And I don't think that we will see it become a commercial product until they've figured out how to compact it like a PC and resolve the overheating issue due to the movement of particles.

It's utterly false information and pure speculation. If you had any idea of quantum computing technology, you would not make such nonsense statements.


Once again, you are completely wrong. That is not how quantum computers work.

OMG, the quantum computer threat again, we have ben over this on the forum on
numerous occasions. Read what @o_e_l_e_o is posting.

I can hear the level of concern some people have and I can sense it turning to panic
all for nothing.

Quantum Computers will be better utilised to contribute to the Bitcoin network and or
put into service by mining Bitcoin.

Also the Bitcoin development team dont sit around drinking coffee and playing games
they work on an unhackable decentralised cryptographic currency technology, and
will continue to do so.

It is how the cryptocurrency can adapt to risk and Bitcoin is the strongest cryptocurrency. Bitcoin is created by satoshi and its total supply will be mined in more than 100 years. Many things will happen in one century and not only Quantum computers but Superb Quantum computers or anything very stronger than Quantum computers can be produced. However, with the fork adaptation, Bitcoin will adapt to risky computers and it will not be broken by new generations of computer.

Nobody can prevent forking process from Bitcoin. After the community vote and reach consensus, fork will be done.

People need to understand that quantum annealing isn't applicable to breaking ECDSA because it can't be used with Shor's algorithm. Quantum computers at its current stage are still underpowered such that it makes no difference to the security in the near future. You can't do much if you can't get a sufficiently powerful QC, which should be about 1200 qubits or thereabout for ECDSA.

There is no way in hell governments will let quantum computers out in public. You can break encryption and all the metadata collected by your agencies can then be cracked, why would they sell it to the general public?

Your existing addresses are all vulnerable, so is millions of Bitcoin left untouch in their original addresses. I'd cast some doubt on trying to reach consensus on sensitive issues like these. It is a far, far more complex issue than just forking Bitcoin.

Why? Addresses which have not revealed their public key are quite safe, no?

This is by far the more contentious issue and the one which will require much more discussion than forking to a quantum resistant algorithm. If sufficiently powerful quantum computers come along, then there will be consensus regarding forking to a quantum resistant algorithm, otherwise it will be the end of bitcoin. What there won't be consensus on is what to do about all the coins in reused addresses and old P2PK addresses which are susceptible to being stolen, including ~1 million bitcoin which are theorized to belong to Satoshi. I am very much in the "Well, let them be stolen camp", but I know that we disagree on this issue.

Woops, wrong choice of words. I meant those either with their public key revealed or P2PK and with the owners having no means of retrieving them.
Yep, correct. We've had quite a discussion in that other thread as well.

Regardless, it would be quite hard to tell if there would be disagreements about solving the issue in the future as well, would probably have a myraid of schemes to choose from. Agreeing to solve the issue is a no brainer, how to solve it is also another potential problem.

We have researched and found out that this topic had been long ago discussed many times as a matter of concern, but we came to know that quantum computers are not going to be a threat to bitcoin network or any of its private keys.

Please watch https://bitcointalk.org/index.php?topic=5195169.0

And if quantum computers were made to harm crypto, they would have done that already as IBM have their quantum computers, Google have them too. The major issue is, are these institutions going to touch these wallets to destroy crypto in general? Or are they not interested in touching crypto at all and will go on with what purpose these quantum computers are made for? That's the bigger question.

No, they wouldn't. The quantum computers currently being researched around the world are not even close to powerful enough to even consider attacking a bitcoin key pair. It will be decades yet before they pose any real threat.

Why would they? What would be their incentive to attack bitcoin and crypto in general? Cause millions of tech savvy users and thousands of major corporations around the world to lose a lot of money? Hardly a good business plan for a tech company.

On the contrary, around 2030, Hackers or Governments using Quantum Computers will not harm Bitcoin but do good that is recover all the lost millions of Bitcoins in dead dormant btc addresses that have been gathering dust never recovered. If that could happen then that would be a good thing right as it will satisfy the btc demand at that time. But then again if this happens then it will stop demand and crash the btc price right  ???

Bitcoin is Bit Binary 1's and 0's digital based on the traditional Moores's Law harwdware that is nearly maxing out now so eventually the world will change over to Quantum Computing that is not digital. From the start of this Quantum tech new area we will see the most advancement in human history so much that all the latest digital tech we see today will be laughable by future generations in lets say 50 years time. Travelling at the speed of light or even time travel is possible under Quantum technology & its advancement  8)

I bet alien civilisations in the universe are already using Quantum computers systems. I wonder how Will Smith & Jeff Goldblum manage to upload a old fashioned binary digital virus onto the quantum alien computer systems on the alien mothership in the film independence day  :D

Okay jokes aside Quantum Mechanics, Quantum Physics and Quantum Computing is just weird stuff. Quantum physics goes against everything you learnt in normal physics.

Quantum Computers will be used to figure out what's going in black holes in the universe that scientists to this day still cant figure out with binary supercomputers they have today so the best answer they come up with now is several theories that can be any one of them

Quantum era will eliminate all the scientific theories we have been taught in school and establish more scientific facts.

All that said above you guys sure Quantum Computers cant decrypt Bitcoin  :o?

Yes. People will start panicking, but again depends on whether they're willing to spend a few millions or even billions to recover a few million bucks worth of it.
Look, there is nothing to decrypt in Bitcoin. Nothing on Bitcoin is encrypted, or at least by design. It is possible to store encrypted strings on it but that is not the question here. Quantum computers will eventually crack ECDSA or asymmetric cryptography, which basically means all the cryptography that we're using for security online. Which also means thousands of terabytes of sensitive data that the governments would love to get... Don't you think it is far more worth it to get those than to get a couple of Bitcoins?

Point is, quantum computers will be very expensive to use and potentially fairly unstable at the earlier stages. We're still decades away. But by then, we would've introduced alternative schemes and adopt them to largely mitigate the threat of it, at least. Pre-emptive measures are always possible.

Quantum computers are one of the biggest enemies of the  blockchain, but I think by then newer and more powerful APIs will be built for the blockchain, and blockchain knowledge will increase to counter them.

The last bitcoins wont be mined till 2140. Satoshi is a mathematician more than a computer scientist and when he did the bitcoin whitepaper he probably didn't know or heard of what quantum computers are at the time.

I can assure you Quantum Computers will be mainstream way before that.

Cryptography is Encryption hence the word 'Cryptography'. Even the whatsapp app claims to be cryptography as it encrypts message between sender and receiver. Cryptography means hiding the message between sender & receiver. The only way to hide it now is Encryption so hackers cant see your messages.

The only prevention safe measure that i can see of bitcoin in the the future is the Bitcoin 'Quant' Hard Fork or Layer 2 Solution. Renaming Bitcoin to Bitqoin with a q yeah I know sounds crazy. :o

Hackers might just attack bitcoin with quantum computers not for money but for fun.

Just imagine a teenage hacker having a quantum computer in his bedroom right now. Hes the only hacker with a quantum computer in the world. He can turn the world upside down and cause so much chaos worldwide as 90% of the world is run on computers now so yeah its not just bitcoin quantum hackers will go after.

"The public" are most likely to be the last people to ever get hold of this sort of technology. The very richest private investors and institutions, if not governments, are the ones driving this technology to the very edge of it's capabilities right now. Ironically that sort of computing power should be able to create defenses against hackers so unless they somehow get access to a separate control interface then it is unlikely they'll be able to do much nefarious with it either. Eventually computing power will be able to overwhelm the defenses of current technology, but you have to wonder whether Bitcoin or other financial services will be able to adapt to an emerging threat more quickly - if it is even possible to defend against, as 2-factor authentication and limiting access attempts might be required.

Doubt so. Even if he did, QCs were too far away of a threat that it still made sense to use ECDSA.
Maybe. Who knows?
It is a misnomer. Definition of cryptography, as specified in RFC2828 states that; The mathematical science that deals with transforming data to render its meaning unintelligible (i.e., to hide its semantic content), prevent its undetected alteration, or prevent its unauthorized use. If the transformation is reversible,cryptography also deals with restoring encrypted data to intelligible form.

Cue the bolded part which concerns Bitcoin. If you disagree, please highlight the part in Bitcoin that would prove otherwise.

Yes.

This is a very common misconception. It is true that many of the encryption algorithms currently in use are quite vulnerable to quantum computing. But there are already some that are built in such a way that quantum computers cannot crack them. Research into this has increased enormously in recent years.

The whole quantum computer debate has been around for some time, and something I remember an Uber driving to tell me about one time.  He was going on and on about how bitcoin will be taken down by quantum computing etc.  However it seems like no one take in to consideration that the blockchain is programmable and there will be ways for the Devs to update the blockchain.  I'm not sold on Quantum being a huge deal at all.

The day we "get" quantum computers, is the day we "get" quantum ASIC miners to balance the equation.

Tech firms seeking to develop quantum computers need funding and resources. That's where "5 to 10 years" comes from. They exaggerate and make overambitious and overzealous promises to attract investors. The technology will likely never become a reality. It shows in the 5-10 year estimate that they have no real blueprint or roadmap.

Anyone who looks into the specifics of claims made by "quantum computer developers" will see many different forms of sketchy and shady behavior. That are not found in legit peer reviewed research.

Thanks for the knowledge. As far as I know, there are several quantum computer (or I should call quantum processor) in the world right now and they have been proven to solve problems which can only be done by them (quantum supremacy). But it is true that only some specific field that quantum computers are faster than supercomputer

Well, quantum algorithm might be the solution when there are thousands of quantum computer existing. They will surely enhance the strength of bitcoin and its private key

They aren't true quantum computers. The number of qubits isn't of any significance if they cannot be used to achieve what we need. The current quantum computers that you see, ie. by DWave claims to have a fairly high qubit but the technology that they're using to achieve it is quantum annealing. Quantum annealing cannot run Shor's algorithm to achieve the exponential decrease in the time taken. They are used for entirely different applications, universal gate QCs are the ones which are of concern.

This is a very interesting article. It is also scary as we do not know if these computers are capable of exploiting the blockchain or by making sabotage the mining industry by creating 51% attack. We do not what will happen next. But I doubt their claim of getting anyone's private key in a fraction of seconds.

Willing to bet that we will be seeing the exact same subject line for posts 10 years from now  ;D
In short - not gonna happen in this decade. From the research articles I've read we are still a long way from running any sort of complex programs that go beyond simple math exercises.

Quantum ASICs don't protect against quantum computers attacking individual key pairs, though. If we ever get to the stage where quantum computers can solve the discrete logarithm problem in a reasonable amount of time and calculate a private key from a known public key, then it doesn't matter what hardware is securing the network - we will need to fork away from ECDSA to a quantum resistant algorithm. This is entirely doable, and for most people would simply mean moving their coins to a new address type, as we have already done with segwit.

And even when we finally get a quantum computer capable of breaking ECDSA, it will still take it weeks or months to reverse a single public key. It will be decades more before they are fast enough and powerful enough to do so in <1 hour and consider attacking a public key which has only been revealed for the first time when a transaction has been made.

This is not a good thing. First, it would be stealing from those people. There is no guarantee that any of them have lost access, no matter what people believe. Very early bitcoin was filled with tinkerers and people who believed in its vision. If you put a key into cold storage for 10-20 years, then should others be allowed to take it?

Second, it would make bitcoin useless. If there is no security and ability to verify owners with private keys, then there is no bitcoin and no cryptocurrency. It removes a significant independent voice within finance.

As for whether it's possible, bitcoin uses two algorithms for signing. While private-public key pairs will be more easily determined, I believe that segwit resolves this by obscuring the public keys behind hashes, which hashing function is much more efficiently solved by non-quantum computers -- and still takes quite a long time. This does mean that the owners of very dormant addresses may have limited time to move their keys to new addresses if the public key is known, but it should provide no difference to addresses without publicly known keys.

OP, tell me something.....

You are saying that there are a few quantum computers in existence today... So tell us, how many of these quantum computers have successfully acquired even 1 Private Key? This would have been blasted on all news media platforms ..if that was true.... but it is not true. It is not as if it is not productive to do this, because 1 000 000 of Satoshi's coins are still out there... so if they can do this, then they can cash in on a major treasure.

Even if they are successful ..some time in the future, then developers will fork to a new coin with stronger encryption and people will just shift their coins or use the new forked coins. (Full nodes will just be too happy to allow this, because it will protect their coins)  ;)

All addresses, be they legacy or segwit, are derived from hashes of the public key. It is only very early transactions which used P2PK - pay to pub key - which do not use hashes of the public key and would be inherently vulnerable to quantum computers. All addresses in current use are only vulnerable if they have already made an outgoing transaction and therefore revealed their public key.

I think it is a very interesting topic that needs to be discussed further and it would be useful if there is a resource person who was knowledgeable enough about quantum computers. Anyway base on the reply's above many tech-savvy forum users are sharing their knowledge about quantum computers so it's a very useful OP,

Anyway, IMO, If quantum supremacy was already achieved ( because I doubt it personally) I think they need much time to improve it and develop further to make them more powerful enough to crack even a single private key, sounds futuristic right? but believe me, it is not an easy task to do. thats why I believe it has no reason to be alarmed about quantum computers.

They will difinetly have access to them in 10-15 years or so. And I dont know what we all wil do about encriptions in our life

But wouldn't the quantum computers be able to decipher the hash of those private keys? Because they're made to make calculations that could last for about a million years to be solved shortened in a matter of seconds, will it be a threat?

No. Not every calculation is the same. Some calculations would be exponentially faster with a quantum computer, some would be linearly faster, and some wouldn't be faster at all.

Turning a public key in to a private key is particularly susceptible to quantum computers. A quantum computer running what is known as Shor's algorithm could reduce the number of operations required from 2¹²⁸ to somewhere in the region of only 128³. This number of operations is trivial for a standard computer, and so quantum computers will eventually reach this stage also.

However, reversing a hash and calculating a public key from an address would only experience a linear speed up. The best method for doing this, Grover's algorithm, only reduces the search space for SHA256 from 2²⁵⁶ to 2¹²⁸. 2¹²⁸ is simply too large a number to be threatened by any computer, quantum or otherwise. The entirety of bitcoin is built on security of 2¹²⁸, and nothing has ever come even close to a tiny fraction to the number of operations required to break it.

Those quantum corporations are owned by the big tech giants such as google, Microsoft and such. If they do decide to attack bitcoin then the bitcoin community will know who to blame and the reputation of these tech giants will fall as they engaged in illegal hacking crimes.

---

Normal legacy physics and maths and computing is based on certainty, logic, truth equation, predictable patterns and such.

For example speed of light is a constant 299,792.458 km per second. This value never changes always the same as its like its has been programmed to be from the start and never goes below or higher than it. Its certainty. Light can be measured in waves and frequencies and these are predictable repeatable patterns.

Quantum is the weird opposite stuff as its uncertainty, unpredictable, the impossible. Like a light switch being on and off at the same time yet the light is on and off at the same time. Sounds impossible I know but Quantum is making impossible seem the possible.

500 years ago if anyone has said the world is round then you would have been called crazy mad lol.

If Quantum can do the impossible then getting private keys is a walk in the park for quantum.

Quantum is just not a threat for Bitcoin its a threat to Central Banks upcoming CBDC's too.

I wonder how governments & central banks are preparing against quantum computers that are a threat to their CBDC's?

I believe not far in the distant future Quantum computers will recover the lost bitcoins in the dead btc wallets.

[moderator's note: consecutive posts merged]

Not really programmed from the start, it is an observation.
Quantum isn't like a silver bullet, it still obeys physics but it's just that it is not immediately clear what we can do with it. The issue here is with the recovery of PK keypairs, and no one is denying that it is possible. We have proven that Shor's algorithm is able to factor integers far faster than classical computers. I don't think that it isn't possible in the distant future, but that it would be so expensive that people wouldn't bother with it. By then, most would've shifted to a different algorithm or the remainder *could've* also been burned.

The value absolutely does change. Light propagates at different speeds in different medium, and different wavelengths of light also propagate at different speeds in those medium. In the most simple example, that's how a rainbow forms - from the different wavelengths of light from the sun propagating at different speeds through water droplets.

Quantum computers make some specific things which are simply too difficult with standard computers much easier, but they can not solve any and every problem, such as turning an address back in to a private key.

No, it isn't. It will be possible in select cases as we've discussed above, but even when finally possible, will still take a prohibitively long time for many years until quantum computers are much improved.

CBDCs will be entirely centralized, and so there is zero trade off for them to implement quantum resistant algorithms.

o_e_l_e_o has already answered it in the best way possible. And even if it may not take "centuries" as he claimed, I would say that we are safe for at least the next 10-15 years. And by some miracle if it happens earlier, then all it takes is a hard fork to change the SHA-256 algorithm to something more secure. Some of the altcoins may be impacted in the future by the advance in quantum computing. But I don't really foresee any real challenge to Bitcoin. If the status quo remains for another 10 years, then it will be enough for me.