Would Quantum Computer Kill Bitcoin

[bitcoinst]

A quantum computer is an extremely expensive thing, which means that only corporate giants such as Microsoft, IBM, Google, Alibaba and others like them can own it.
Hackers will not be able to access resources for hacking such a computer, and moreover they will not be able to have at their disposal a whole quantum computer.

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[NathanJB]

There is already a thread here in this same section which discusses about quantum computers not too long ago. There is no need to duplicate topics. But anyway, let me say my piece on this. This is more of a talk of the town for the past weeks or so. But then more of this talk does not actually exist in reality. More of this talk is only found in the imaginations of people who are mostly idle or fond of turning otherwise normal developments into a much more complicated one.

[Arsenyo]

It is unlikely that quantum computing technology will fundamentally threaten the existence of bitcoin. Each year, when new hardware is released, appears a lot of concerns about the blockchain’s integrity, but there is actually no evidence that quantum computing can compromise blockchain. I don't believe it.

[Artemis3]

I am not a cryptographer myself so maybe here we are just discussing on a normal guy's level. As far I know, quantum computing really has the potential to successfully decrypt the private keys and therefore can be the biggest threat to Bitcoin. In the past few days, this topic got spread around because Google announced that they already have the technology at hand which many of us supposed  should still be years ahead. Now, there is that fear in the Bitcoin community on quantum computing and whether this can really be utilized against Bitcoin which can be its end. Nobody can really be sure if the quantum computing developed by Google can effectively be the one to stop Bitcoin. This can be the one we can only wait and watch. As the technology is on the hands of Google, I don't think they will be irresponsible to just use it indiscriminately as this will have many legal repercussions which the company will not want to go through. On the other hand, we have to remember that if there is a demand someone will eventually fill the shoes therefore we should be expecting developers to come up with ways to counteract the power of quantum computing to balance things out. And this can actually make things exciting.

If you are a cryptographer you must have known about this way before most "common folk" that recently panicked over this "news". I do not believe what they say that Satoshi did not know about this, i'm sure that was discussed back then, i certainly knew and i am no cryptographer or cypherpunk tho i did read their writings from time to time.

This was very theoretical as you say, and people were already writing programs that would run in these theoretical machines, years later there were even simulations with classic computers (which of course were way too slow but they were just testing concepts anyway).

Well this was years ago, and time didn't stop. If google didn't mention a thing (like IBM), did you think no advances were being made? I clearly remember when the first few qbit machines started becoming operational, but of course almost nobody knew what that meant...

But here, years later, you bring the exact same excuse. Its still theoretical, lets wait. Actually, the wait is over, the writing is on the wall. Panic is for fools, there is still time to act, but act you must, not sit still and wait the next decade to learn that, sure, some agencies already are decoding everything online.

There are proposed mitigations to improve Bitcoin resistance to quantum attack, those should be revisited, now that there is time, and not wait for later.

We are still too far from quantum crypto (hardware unavailable to the masses), but even that should be considered. This is the solution to quantum breaking crypto, this side most people don't know a thing about either. But in the meantime, those (classic computer) algos that make it hard for quantum attacks, should be implemented. Transition times indeed...

[SaShiRaJaVu]

It is unlikely that quantum computing technology will fundamentally threaten the existence of bitcoin. Each year, when new hardware is released, appears a lot of concerns about the blockchain’s integrity, but there is actually no evidence that quantum computing can compromise blockchain. I don't believe it.

If some crazy billionaire is spending a huge amount of money to destroy bitcoin, then it might be possible but what is the point of breaking something by spending huge amount of money. The fact is that the quantum computing is just a dream but technology is changing pretty fast and with those changes we will have better secure technologies too.

A quantum computer is an extremely expensive thing, which means that only corporate giants such as Microsoft, IBM, Google, Alibaba and others like them can own it.
Hackers will not be able to access resources for hacking such a computer, and moreover they will not be able to have at their disposal a whole quantum computer.

Suppose if anyone use those resources to break bitcoin then they can be prosecuted for theft.

[marky89]

I do not believe what they say that Satoshi did not know about this, i'm sure that was discussed back then, i certainly knew and i am no cryptographer or cypherpunk tho i did read their writings from time to time.

I'm sure Satoshi was aware that computing power might improve over time and that cryptographic standards might become vulnerable. That possibility just wasn't worth burdening Bitcoin with something so unwieldy as Lamport signatures, which are much worse for scaling. He probably figured, "cross that bridge when we come to it."

[Wintersoldier]

As far as I know, quantum computer's processing power is increasing exponentially. Through that, its capability to decrypt password or keys from cryptocurrency with an algorithm is quite impossible. But in terms of security of the blockchain, I think it depends upon the hashes of every mining computer around the world. Not all people have their access since google's quantum computer is not open source. I still believe that bitcoin is still superior because of the blockchain. Output depends on the previous and the only way I can think for it to be manipulated is through going back in time.

[fiulpro]

First thing we should understand that nothing in the IT world is safe only , everything has some downsides , when we think about quantum computers and all they can definitely hack into blockchain and then make everything a mess but we should understand that
Hacking , is not legal like this.

When we talk about ethical hacking and all there no one teaches you how to hack in someone else's bank account.

You should understand that you shouldn't worry about new softwares being invented but rather worry about the old one getting updated .

[squatter]

Now the issue is that ECC is NOT "quantum-safe" meaning that a quantum computer could theoretically decrypt a user's private keys and forge transaction signatures.
Is this the end of Crypto?
I don't think so, but I'd love to hear your opinions too! (Especially the opinion of a cryptographer)

Here's what Bitcoin developer Pieter Wuille said a few months ago:

Any unconfirmed transaction in flight exposes public keys, so if a QC exists, at least moving coins around safely becomes impossible. Further, a massive fraction of the currency supply can be taken. Lastly, you likely have exposed your own pubkey already.
https://twitter.com/pwuille/status/1133539556936912896

If there's ever evidence of theft due to a QC, and 5M BTC are readily available for the taking to such a hypothetical machine, do you think BTC will still have any value left?
https://twitter.com/pwuille/status/1133537183854239745

It sounds pretty grim. I didn't realize that P2PKH outputs weren't really secure against hypothetical quantum computing attacks. On top of that, the pubkey problem is really bad. Anyone who has shared an xpub, used Electrum, etc. has exposed pubkeys. It's not just early P2PK outputs or reused addresses.

[Lalafell]

As per the latest, Google has reached Quantum Supremacy. Meaning it could potentially decode an entire blockchain and...
YOUR PRIVATE KEYS...
Blockchains are secured through elliptic curve cryptography (ECC), just like encrypted user data and website traffic. Now the issue is that ECC is NOT "quantum-safe" meaning that a quantum computer could theoretically decrypt a user's private keys and forge transaction signatures.
Is this the end of Crypto?
I don't think so, but I'd love to hear your opinions too! (Especially the opinion of a cryptographer)

source https://www.coindesk.com/what-googles-quantum-supremacy-means-for-the-future-of-cryptocurrency

Humanity currently does not have any technology necessary to create a quantum computer large enough to attack Bitcoin keys. It is not known how quickly this technology will advance; however, cryptography standards such as ECRYPT II tend to say that Bitcoin's 256-bit ECDSA keys are secure until at least 2030-2040. Blockchain companies: IBM, Google and a number of other technology giants are the current movers in developing quantum computing. It is likely that they will not enable users of quantum computing to crack bank-encryption or blockchain. “To do so is illegal and would destroy those companies, by 2025, up to 10 percent of the global gross domestic product will probably be stored in blockchains. Quantum computing is a threat to technology blockchain because it increases the fundamental security assumption of elliptical curve cryptography, namely that computers cannot effectively factor large numbers.

[Alexandr Kirichenko]

I don't think that's something to worry about, at least not right now. In the next 5 years, I think this threat will not be exactly. In the future, who can say that the same quantum computer will not be able to make the Bitcoin network more secure from the vulnerability of the Quantum computer.

[figmentofmyass]

Suppose if anyone use those resources to break bitcoin then they can be prosecuted for theft.

no they can't. it can't be proven that coins taken in this manner were stolen at all. there would be no evidence of hacking or theft; there would be nobody to prosecute. it's the perfect crime.

in fact, it's debatable whether it's theft at all. pubkeys are publicly available so bruteforcing them doesn't require "taking" anything from the victim. they are more so attacking the pubkey-privkey system.

[Mike Mayor]

This is an interesting question. If quantum computing becomes this powerful then how will we protect our important data? Passwords would no longer work? The computer would crack any algorithm a human can think of so does this mean we will need physical verification such as a retina or fingerprint scan? That's scary that passwords would not be safe anymore. Bitcoin wouldn't work anymore and most other things too. After all what code would be safe if this quantum computer can just crack it?

[darkangel11]

This is an interesting question. If quantum computing becomes this powerful then how will we protect our important data? Passwords would no longer work? The computer would crack any algorithm a human can think of so does this mean we will need physical verification such as a retina or fingerprint scan? That's scary that passwords would not be safe anymore. Bitcoin wouldn't work anymore and most other things too. After all what code would be safe if this quantum computer can just crack it?

This is a game hackers and programmers have been playing for decades. If you had a computer from the 80s with all its security and had a chance to use a modern computer and a modern hacker to break into it you would succeed without problems. Now people think that quantum computers that aren't even usable will break Bitcoin's encryption. By the time they become used for that purpose Bitcoin will be in another era.

Now you're comparing a technology from 2010 with a technology that could be online in 2030. In 2030 Bitcoin will be upgraded so much that it will be able to withstand a quantum attack.

[boltz]

Not gonna happen but imagine the amount of mining power that it can generate , that would be a threat for sure. Besides that, quantum computer is not here to kill Bitcoin or even to threat it as the tech it has was build for another sectors and so far there are only 2 knowing brands that posses something like this. The quantum tech is still in development and maybe in some years we can talk about how it can threat the bitcoin future,replace it ,kill it or even help out in the security system because anything is possible regarding this gigantic technology that took us by surprise.

[lighpulsar07]

Well yeah a quantum computer can solve a sha 256 algorithm within a second from the articles about quantum computer online although don't be worry a quantum computer is costly and only a huge companies like google can build and own one and no one ordinary person can build or buy a quantum computer anyway just relax and don't panic.

[timerland]

I think it'll be a pretty big risk to assume that BTC would be safe when quantum computers come around, using today's gear, it'll obviously almost be impossible to decipher someones private key, but with quantum computers, almost anything is possible.

The real question here is when are they becoming a real thing? We've talked and theorised about this technology, but I don't think we'll see anything that powerful until 20-30 years.

[bounty.bn]

We have heard a lot about Bitcoin dying. There are so many new blockchain platforms out there and also want to beat Bitcoin for over 10 years. Of course nothing is everlasting. In theory, Bitcoin can be defeated, but actually Bitcoin still exists and is getting stronger. So with what we see Bitcoin developing, it can't be beaten by Quantum. And I am confident that Bitcoin will be more and more powerful and improved in the future and at least 100 years more or even more...

[7788bitcoin]

I think it'll be a pretty big risk to assume that BTC would be safe when quantum computers come around, using today's gear, it'll obviously almost be impossible to decipher someones private key, but with quantum computers, almost anything is possible.

The real question here is when are they becoming a real thing? We've talked and theorised about this technology, but I don't think we'll see anything that powerful until 20-30 years.

Hypothetically we can kill anyone with the help of quantum computers and the entire system can be hacked and we might see cyber war on a larger scale where countries will try to hack their enemies financial system and so on. These are all hypothetical scenarios and anything is possible in the future but for that to happen first there must be billions spend on testing and creating the perfect machine to hack the current security systems and if they try to come up with powerful technology in the next 20 to 30 years the security protocols will also gets updated.

[rahmatullah9305]

When viewed from the rapid development of technology, one day surely bitcoin can be vulnerable too. But not all things have a bad impact, if in my opinion there is a positive side too, bro. quantum computers in one computational step can carry out mathematical operations on 2N different inputs stored in coherent N qubit superpositions. For the same thing, a conventional computer must repeat a number of operations 2N times or must use 2N conventional processors that work simultaneously. Quantum computers offer a tremendous increase in the use of two main computing resources, namely time and memory.
If quantum computerization is included in the operation of data I think bitcoin is not vulnerable because bitcoin is difficult to track because it is anonymous.