Quantum chip solves travelling salesman problem for 22 cities
https://www.electronicsweekly.com/news/research-news/quantum-chip-solves-travelling-salesman-problem-22-cities-2020-01/'''According to the university, this is something that would take about 1,200 years for a high-performance von Neumann CPU, but the chip can solve the travelling salesman problem for 22 cities instantly until now using quantum processing it has only been able to solve the travelling salesman problem involving a maximum of 16 cities.
A quantum annealing computer is not a full-blown quantum computer, of the type that could crack encryption for example, which no one has yet made or if they have, they are keeping quiet about it.'''
It's an interesting development, but yes, a quantum annealing computer can't be used to break cryptography, and will never threaten bitcoin. The annealing approach is more for problems where there are a huge number of possible solutions, and we're just looking for one that is sufficient out of that multitude of possibilities.
The biggest threat to bitcoin from quantum computing, as I've
outlined previously, is the use of Shor's algorithm against re-used addresses:
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 Shors algorithm to break public-key cryptography. This is a quantum algorithm designed specifically to solve for prime factors. As with Grovers 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 Shors approach to derive the private key. The vulnerability cannot be overstated here. Any re-used address is utterly insecure.
... but a quantum annealing computer (the type that is used above for the Travelling Salesman problem), is not going to run Shor. For that you need a universal gate QC, which is generally what we mean when we refer to a 'quantum computer'. I remember all the fuss about D-Wave, but the mainstream media tended to overlook the fact that D-Wave is an annealer, not a fully-fledged UG-QC.
My opinion:
Quantum computers will surprise the Bitcoin community..
My opinion is actually the exact opposite. I think that crypto developers, certainly for the big coins, and most definitely for bitcoin, are well aware of potential threats from quantum computers, and are actively developing safeguards.
We've covered previously and in considerable depth what QCs can and can't do. Asymmetric cryptography is massively vulnerable, but symmetric cryptography far less so -particularly AES256, as discussed above. It's a common misconception, perpetuated by mainstream media, that QCs instantly break all types of cryptography in all circumstances, when that is clearly not the case. QCs are great for certain specific types of problem, but it's technology, not magic, and it has limitations.
I am some random uninformed idiot posting opinions on a web forum, and even I am aware of what QCs can and can't do, and of the nature of their potential threat to cryptocurrencies in certain situations. People far smarter than me are developing these coins, and I'm absolutely certain that they are on top of the QC question. This is why I am convinced that the threat of QCs will not come as a surprise.