Do quantum computers have any security risks associated with them?


I would, like to know for my company, as we are looking to start the process of moving towards quantum safeness.


Posted 2021-01-08T12:07:21.427

Reputation: 5

Question was closed 2021-01-09T15:13:14.343


Hi Codenix47, and welcome to the QC Stack Exchange! Currently this question is very broad, something which is unwarranted - please check the guidelines here. Can you elaborate on what you mean with security risks, and with quantum safeness?

– JSdJ – 2021-01-08T13:40:27.777

All IT systems are quantum safe now. – peterh - Reinstate Monica – 2021-01-09T00:18:27.187



Quantum computing is so far away from anything that would ever have to worry about security risks.

It's very much debated how far away we are from having a quantum computer, but I personally think it'll be decades before "security risks" are even worth speculating about.

There is an effort to build a "quantum internet" which connects quantum computers with entangled qubits, and could connect long distance networks for QKD. But to be frank, connecting the world with QKD is not as useful as just switching to post-quantum protocols for normal cryptography. In my opinion, the appeal of a "quantum internet" is for applications that need distributed entanglement (or for connecting quantum computers), not for QKD.

Steven Sagona

Posted 2021-01-08T12:07:21.427

Reputation: 723

Unlike post-quantum protocols, QKD allows for long-term safe encryption. Stuff encrypted with a classical post-quantum technique can be stored and then possibly decoded in 50 or 500 years, when more powerful computers are available. – Norbert Schuch – 2021-01-09T15:14:47.603

I think the current belief is that lattice based cryptography is unhackable by a quantum computer in the sense that a quantum computer doesn't offer any significant speedup, although I cannot find any discussion of what exactly that speedup (or lack of) would be.

– Steven Sagona – 2021-01-09T19:25:13.863

Forget quantum computers. But common keylengths which look unhackable today might be hackable in 30 years from now. Or someone smart might come up with a revolutionary algorithm. (Imagine someone proves P=NP, constructively!) So if you want to keep your secret secret forever with certainty, using a one-time pad (as provided by quantum crypto) is the only safe way. (Of course, then there are still enough ways to mess it up.) – Norbert Schuch – 2021-01-09T19:39:46.853

Okay, I see your point. – Steven Sagona – 2021-01-09T19:50:26.870