Topic: Quantum Computer Will Destroy Bitcoin (Read 352 times)

In theory and in practice, such a threat still exists.  When it becomes reality, it will be too late for many to panic.  They will simply be at a loss to consider their empty wallets.  However, the first thing to be wary of is the big whales.  In this case, they will be the first to be targeted by attackers.  Let's hope that by that time they will find how to secure the cryptocurrency from this problem.

Quantum Computer? How it could affect on Bitcoin

Hi all   I thought I’d try to summarise Bitcoin's vulnerabilities to Quantum Computers, as well as some potential defences, and get it all in one post. Apologies for the wall of text, but hopefully it is useful...


Mining can potentially be much quicker with QCs.
The current PoW difficulty system can be exploited by a Quantum Computer using Grover’s algorithm to drastically reduce the number of computational steps required to solve the problem. The theorised advantage that a quantum computer (or parallelised QCs) have over classical computers is a couple of orders of magnitude, so ~x100 easier to mine. This isn’t necessarily a game-changer, as this QC speed advantage is likely to be some years away, by which time classical computers will surely have increased speed to reduce the QC advantage significantly. It is worth remembering that QCs aren’t going up against run-of-the-mill standard equipment here, but rather against the very fast ASICs that have been set up specifically for mining.

Re-used BTC addresses are 100% vulnerable to QCs.
Address Re-Use. Simply, any address that is re-used is 100% vulnerable because a QC can use Shor’s algorithm to break public-key cryptography. This is a quantum algorithm designed specifically to solve for prime factors. As with Grover’s algorithm, the key is in dramatically reducing the number of computational steps required to solve the problem. The upshot is that for any known public key, a QC can use Shor’s approach to derive the private key. The vulnerability cannot be overstated here. Any re-used address is utterly insecure.

Processed (accepted) transactions are theoretically somewhat vulnerable to QCs.
Theoretically possible because the QC can derive private keys from used addresses. In practice however processed transactions are likely to be quite secure as QCs would need to out-hash the network to double spend.

Unprocessed (pending) transactions are extremely vulnerable to QCs.
As above, a QC can derive a private key from a public key. So for any unprocessed transaction, a QC attacker can obtain the private key and then create their own transaction whilst offering a much higher fee, so that the attacker’s transaction gets onto the blockchain first, ahead of the genuine transaction. So block interval and QC speed are both crucial here – it all depends on whether or not the a QC can hack the key more quickly than the block is processed.


Possible defences...

Defences using classical computers.

• Modify the PoW system such that QCs don’t have any advantage over classical computers. Defending PoW is not as important as defending signatures (as above), because PoW is less vulnerable. However various approaches that can protect PoW against QCs are under development, such as Cuckoo Cycle, Momentum and Equihash.
• Modify the signature system to prevent easy derivation of private keys. Again, various approaches are under development, which use some pretty esoteric maths. There are hash-based approaches such as XMSS and SPHINCS, but more promising (as far as I can tell) are the lattice-based approaches such as Dilithium, which I think is already used by Komodo.
  

Defences using quantum computers.
As I’ve said a few times, I’m more of a bumbling enthusiast than an expert, but exploiting quantum properties to defend against QC attack seems to me a very good idea. In theory properties such as entanglement and the uncertainty principle can offer an unbreakable defence. Again, people are busy researching this area. There are some quite astonishing ideas out there, such as this one.

Quantum computers are still not as close as you think, so don't think about it now.

Yeah, about that. How exactly are we going to do this? Bitcoin developers can't just make many changes to the code. I will be considered as fork. Also, even if they can, the damages that will have been caused from quantum computers will already be huge.

This shared agreement (called consensus) allows people like you to only accept valid bitcoins, enforcing Bitcoin's rules against even the most powerful miners.In addition to improving Bitcoin's decentralization, Bitcoin Core users get:

    Better security for their bitcoins
    Privacy features not available in other wallets
    User interfaces and other powerful features

Hello there, I have a question that annoying me last days.

Can anyone explain me please, what happen if Some organization (corporation or country or maybe even some group of people) create Quantum Computer?
How it could affect on Bitcoin if this (let say group of people) want to destroy the whole system.
As I understand with the Power of such computer you could easily select private keys or create a 51% attack?
And probably give advice what to do in that case, I mean it would be enough to store my Bitcoin on cold wallet(It would be safe?), or panic sell in physical gold))

Thank you in advance.

Hello there, I have a question that annoying me last days.

Can anyone explain me please, what happen if Some organization (corporation or country or maybe even some group of people) create Quantum Computer?
How it could affect on Bitcoin if this (let say group of people) want to destroy the whole system.
As I understand with the Power of such computer you could easily select private keys or create a 51% attack?
And probably give advice what to do in that case, I mean it would be enough to store my Bitcoin on cold wallet(It would be safe?), or panic sell in physical gold))

Thank you in advance.

Hello there, I have a question that annoying me last days.

What quantum computing can do in theory is derived your private key if your public key is exposed. So if your public key is not there then there's no way that even a super computer can hack a private key.

And I'm sure that once bitcoin or blockchain is vulnerable, then we will have a consensus to go to the next level of cryptographic hash.

The other catastrophic theory is that a quantum computer can brute force a sha256 result. I don't know if that'll be true. I hope not. Otherwise, bitcoin is dead. As for the 51% attack, I wouldn't worry. Even if it happens, it will be something temporary. Sooner or later, the computer will spread to the rest of the world.

Quantum Computers are not just super fast computers. Computer made by this technology is specified to solve a specific problem. It needs months and huge money to calibrate it to do this. So if any day there will be quantum computer that will try to attack bitcoin - it will be made in purpose to do only this one thing. Will it be profitable? Probable not because simple fork will make this quantum computer useless.

And you also need to know that this is very far future. And only few companies works on that technology. So in next 10-50 years Google, IBM and someone else mine purpose of doing quantum computers most likely will not be destroying bitcoin - there are more fun, needed for society, profitable aspects that will be the purpose of quantum computers rather than shot to the knee from marketing point of view.