Quote from: PrimeNumber7 on July 21, 2019, 07:59:24 PM

Quote from: Saidasun on July 16, 2019, 09:56:02 AM

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.

I posted why I don't think this will happen above. In short, governments have bigger fish to fry than 'destroying' bitcoin.

I agree completely. If someone develops a quantum computer that can break existing encryption with ease, then there are much bigger targets than bitcoin. As mentioned by PrimeNumber7 above, if it becomes public knowledge that someone has hacked bitcoin and stolen say $1 million of coins, then crypto will take a nosedive and that $1 million will fall in value very very rapidly. If they steal $1 billion, then I'd be very surprised if they could cash it out to fiat before it lost most of its value.

We all know how volatile crypto prices can be, with even the merest suggestion of a rumour of bad news often enough to cause the whole market to tank. Something like a quantum hack would have a huge impact. If this hypothetical malicious actor with a quantum computer wants to make a huge amount of money, they could go after banks instead - that would be much more lucrative and probably easier. And if it's a government doing the hacking, then again it would be much more advantageous for them to hack a rival government (US vs China for example). They could wreak havoc, with infrastructure a likely target, but in theory any state secrets or corporate data would be vulnerable.

Finally we must also remember that one of the best things about crypto is that good coins are under continuous development, and defences against quantum attack will likely be in place long before it becomes a real risk. These coins are developed by some very smart and very tech-savvy people. If quantum computing becomes a threat, it won't take these people by surprise.

As I've mentioned before, I think that whilst a lot of work has gone into building quantum-resistant systems using classical computers, one of the best avenues of investigation is defence using quantum computers. There has been plenty of research into various methods of Quantum Key Distribution, and this research continues with approaches such as Kaks three-stage protocol. Perhaps this will be quantum-attack-proof, or perhaps not. But the key here is that defence is actually moving faster than attack.