3 ms·

What's a post-quantum key exchange? I assume this is a real thing and not a reference to Devs or Lapsis or something?

by ilaksh 5y ago

tialaramex 5y ago
So. All of today's practical public key crypto could be broken by a sufficiently powerful quantum computer - if one existed which today it does not - thanks to a trick called Shor's Algorithm. However, there are new public key algorithms that aren't affected by Shor's algorithm. Two problems. 1. They're all worse, they have huge keys for example, or they're slow, so that sucks. 2. We don't know if they actually work, beyond that Shor's algorithm doesn't break them on hypothetical Quantum Computers. Even if you decide you don't care about (1) and you're very scared of the hypothetical quantum computers (after all once upon a time the Atom Bomb was also hypothetical) you need to deal with (2). Post-quantum schemes like this for SSH generally arrange that by doing two things, they have the shiny new Quantum Resistant algorithms, but they also have an old-fashioned public key algorithm, and you need to break both to break their security. Either alone won't help you.
- da_chicken 5y ago
  > All of today's practical public key crypto could be broken by a sufficiently powerful quantum computer - if one existed which today it does not That we know of. There are commercially available quantum computers [0] and there are roadmaps for commercial technology ramp up significantly [1]. Remember, that's a roadmap to projected commercial viability. It's hard to say what state actors are capable of right now. [0]: https://azure.microsoft.com/en-us/services/quantum/ https://azure.microsoft.com/en-us/services/quantum/ [1]: https://venturebeat.com/2020/12/09/ionq-roadmap-quantum-machine-learning-2023-broad-quantum-advantage-2025/ https://venturebeat.com/2020/12/09/ionq-roadmap-quantum-mach...

3 ms·

What's a post-quantum key exchange? I assume this is a real thing and not a reference to Devs or Lapsis or something?

by ilaksh 5y ago

What's a post-quantum key exchange? I assume this is a real thing and not a reference to Devs or Lapsis or something?

tialaramex 5y ago
So. All of today's practical public key crypto could be broken by a sufficiently powerful quantum computer - if one existed which today it does not - thanks to a trick called Shor's Algorithm. However, there are new public key algorithms that aren't affected by Shor's algorithm. Two problems. 1. They're all worse, they have huge keys for example, or they're slow, so that sucks. 2. We don't know if they actually work, beyond that Shor's algorithm doesn't break them on hypothetical Quantum Computers. Even if you decide you don't care about (1) and you're very scared of the hypothetical quantum computers (after all once upon a time the Atom Bomb was also hypothetical) you need to deal with (2). Post-quantum schemes like this for SSH generally arrange that by doing two things, they have the shiny new Quantum Resistant algorithms, but they also have an old-fashioned public key algorithm, and you need to break both to break their security. Either alone won't help you.
- da_chicken 5y ago
  > All of today's practical public key crypto could be broken by a sufficiently powerful quantum computer - if one existed which today it does not That we know of. There are commercially available quantum computers [0] and there are roadmaps for commercial technology ramp up significantly [1]. Remember, that's a roadmap to projected commercial viability. It's hard to say what state actors are capable of right now. [0]: https://azure.microsoft.com/en-us/services/quantum/ https://azure.microsoft.com/en-us/services/quantum/ [1]: https://venturebeat.com/2020/12/09/ionq-roadmap-quantum-machine-learning-2023-broad-quantum-advantage-2025/ https://venturebeat.com/2020/12/09/ionq-roadmap-quantum-mach...