Topic: Quantum Computer vs Bitcoin - page 5. (Read 2470 times)

I think it would be more worth it for the attacker to attempt a sybil attack.

It is possible for the attacker to spawn nodes under his control to capture and slow down the propagation but it isn't easy by any standards. The reference client only connects to a node per IP block and it would require a tremendous amount of IPs for the chance to be significant. If any other node is connected to the victim, the propagation would be too fast. The amount of time it takes to crack a key is still way too slow.

I know that quantum computers are still mostly theoretical/at very early stages, so I wasn't asking if Bitcoin is in practical danger (I've read this whole thread), I'm just curious how it could work in theory.



Can attacker try to spawn some virtual nodes to slow down the propagation of original transactions and increase the chance of his own transactions reaching the miners faster?

I heard that Quantum Computer can destroy bitcoin.
Is it possible here?

That’s a huge “if”.  Even if a practical quantum computer existed, what makes you expect it to break public key cryptography “in seconds”?  Please remember that even today, a security level of (say) 80 bits is considered far too weak; and yet, it is not something you should consider “broken in seconds”.  (Try to do 2^80 work, if you don’t believe me.)

But arguendo, assuming your “if”:  Well, then, yes, an attacker could race you to double-spend, or even mine his own block to double-spend your coins.  (I assume that an attacker equipped to break PK crypto “in seconds” could also have a big advantage over other miners.)  In that case, I would be very worried about Bitcoin security.  I would likewise be worried about the security of the entire Internet, the banking system, and everything else which would be totally shattered (worse than Bitcoin) in your scenario.  What would I do about my PGP keys?  My TLS?  My SSH?  Everything else?  Bitcoin would be one of the only things left with even a little bit of security.

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I see that earlier, haltingprobability wrote me an excellent reply.  I should get back to that....

There isn't any credible evidence that ECDSA could be broken using quantum computing in seconds. Even if it could and there is a negligible cost, nodes will not accept transactions with its inputs already spent by another transaction in the mempool.

After learning a bit more about Bitcoin I have a new question about theoretical attacks with quantum computer.

Public keys are generally hashed, so attackers can't use Shor's algorithm against an address that wasn't sending any transactions, but public key is included in transaction, so it gets exposed as soon a transaction is broadcast. If public key cryptography could be broken in seconds, would attackers be able to attempt to steal coins from any unconfirmed transaction by cracking private keys and broadcasting new transactions from the same address?

Intriguing, what are those projects that can kill bitcoin?

Precisely, the first quantum computers are under development and quantum computing has been a hot topic the last few months. There are some interesting developments in the area, for ex. recently Microsoft programming language called #Q -  https://www.forbes.com/sites/fredcampbell/2017/12/18/microsofts-quantum-computing-vaporware/

Edit: There are so many interesting news lately, that a fast google on 'quantum computers' shows a lot of good articles

There are no quantum algorithms out there that really makes breaking hashes used by bitcoins easier.
Yet. The RSA crypto was belived to be unbreakable for some time until it was shown that a quantum computer strong enough would shred it.

Quantum computing is still quite young and the science is complicated on account of there's not really that much of quantum computers to run tests on.
When the quantum computers start to make their way out to the universities and governments, rest assured we'll see some crazy stuff, one of which might be cracks in the bitcoin integrity.
That being said, by that time, quantum encryption will be widespread and implemented in most major crypto currencies.

As it stands, the biggest threat quantum computers pose to bitcoin is the risk of rumors.
Even a false rumor can start a bank run. A widespread rumor about a bitcoin security breach could turn nasty really fast.

It can only pose an imminent threat to bitcoin security it can’t destroy bitcoin and moreover, bitcoin has overcome so many threats in the past.
Although, Quantum Computer will surpass the processing power of today’s classical computers, and if it does then it could break RSA (Rivest–Shamir–Adleman) encryption, a tool used to secure data transmission on the Internet. In a similar vein could also break the digital signatures used in Bitcoin and other cryptocurrencies. And the upshot of that is not good.
I believe that bitcoin will overcome this threat.

It is said that quantum computer's massive calculating power can be able to break bitcoin security within a decade and there are report that the first quantum computer are currently under development. Some also suggest that the bitcoin protocol should be revised to make the system safer. Whether it is true or not, bitcoin must always be prepared to cope with the future's challenges to beef up its security.

I suspect stuff like this is going.

I think we are doomed if this is indeed true. Am sorry for guys who trust earthly government as we know it. You are creating monsters in the name of government.
Powerful entity keeping secrets is DANGEROUS.

One day you will all understand. May be too late by then.

and explain what that protocol is? is this the reason why people's BTC is getting stolen? Cause of this so called "Protocol"

I checked the site I liked what they have done, Most of us are aware of the term 'Ransomware'; lately, it became a very popular term. It is a method by which cybercriminals make money. May be this one can help a little in this rather like movement against Cybercrime.

No. I think it's false.
Bitcoin may not be perfect but surely it's vulnerability is not wholly. I have read that Satoshi knew the risks that bitcoin could face with such developed powerful computers that is why he built a protocol to avoid and withstand attacks. And I think bitcoin is safe against quantum computer but since there are more technological developments coming in the future, we will not know if something could come up to attack bitcoin.

Yes, you are correct it can because it uses quantum-mechanical phenomena, such as superposition and entanglement, and after research I got to know that they are using AI for superposition in which it can choose both on and off (1 and 0) while computing and correct the errors and configure the private keys through public on its own!
I can see that most of people are talking about SHA-256 algorithm

SHA-256 algorithm generates an almost-unique, fixed size 256-bit hash

There might be a solution for this also I have heard about this Blockchain Security system http://blockshield.io/ which can block even AI.

Quantum Computer could be a big help but it does not and can not destroy Bitcoin and it cost a lot money to buy a single Quantum Computer for yourself. It may be a big help if someone would have a Quantum Computer like NASA because it is too powerful to process any large memories of files into it. Anyway, how is this going to destroy Bitcoin, it doesn't makes sense at all.

We just named it and created its features that it has quantum things to do. We are applying them in our real world.
Its not a true science like destroying and it is not possible to break bitcoin. May be quantum computer have advanced technology in it which will not destroy anything.
I don't know why are you thinking about destruction which we can feel only in dreams

The difficulty level of bitcoin mining gets adjusted once every two weeks. the faster the processors, the higher the difficulty level. So no, they won't destroy cryptocurrencies (bitcoin might be destroyed by other things such as competition, however)

What a great resource - bookmarked. There are oodles of false conceptions about SR. If I had to identify one common theme to all of these errors (and the popular errors about QM), it is forgetting that science is about observation and experiment - the maths are just a tool for organizing observed phenomena and guiding further research in an efficient way that hopefully gives us some insight into the nature of physical causality. So, when the popularizers start saying things like, "Physicists have proved the existence of unobserved dark matter and dark energy" (to take one bit of popular science mumbo-jumbo, for example), they are just taking mathematical models and reifying their components as though those components have been actually observed! Instead, mathematical models of physics often use hypothetical components that are merely inferred from experimental data - such as dark matter/energy. At the end of the day, all these formulas describe what happens (or could happen) in a laboratory, in an observatory, and so on. Without that connection to empirical measurement, physics is just really crappy, hard-to-use math.

Thanks for that.  It’s refreshing to read a post by somebody who knows more than I do about a subject.  Though I look forward to the video, I haven’t yet put an hour of dedicated focus to it; I appreciated your brief summary.  Garret’s thesis as you describe it is fascinating, as is Lloyd’s paper.

This seems to intersect; I presume that Garret was taking aim with his “post-Simulation Hypothesis”:  “Because you asked: the Simulation Hypothesis has not been falsified; remains unfalsifiable”.


What evils have been wrought by the wrong metaphors!  (Pseudo)scientifically, and otherwise.  It is the twin sin of asking the wrong questions.


Whilst on the subject of pseudoscientific mysticisms woven under the rubric of “educating the public”, quantum talk seems somehow incomplete without mentioning its spacetime counterpart.  One section of one webpage (plus its companion) will suffice to burn away mountains of garbage from “science popularizers” about special relativity.  It’s not even necessary to work through the equations:  Simply look at the pretty pictures of a ruler on a rotating grid.  The light bulb goes on.  Rulers never change their lengths.  Clocks never tick at different rates.  There are no paradoxes.  Those are only illusions caused by three-dimensional thinking, lack of vector maths, and too many “science popularizers”.  Of course, you probably know this...

Granted, the popular explanations sell better.  They provide an instant psychological substitute for the theological paradoxes and impossibilities of popularly fading religions.  It’s not the first time in history that similar has occurred.

As for myself:  I don’t understand special relativity.  I don’t understand quantum mechanics.  I know just barely enough to know that I would need to dedicate years of intensive study to properly claim such understanding.  I’m disgusted by the culture of “popularizers”, and the mass pretense that anybody but a few elite scholars can understand such things; these eviscerate the meaning of the word “understand”.  Attainment of actual understanding in any scientific discipline or engineering endeavour requires both innate ability and hard work.  The same applies as for any art worthy of the word.

But hey, who am I to speak?  I heard that quantum mechanics proves we have entered the astrological Age of Aquarius.  Also, it explains psychic powers.  Thanks, popularizers!


Quantum FUD®.  What a most excellent buzzword.