What the Quantum Internet Has in Store • Hacker News Board

Re: What the Quantum Internet Has in Store

#11

Post by krastanov » Mon, Oct 29, 2018, 3:48 PM UTC

bloomer wrote: post #8

krastanov wrote: post #7

Earlier quoted context omitted.

I think you are conflating two similarly named topics, or at least missing the point of why one of them is useful. At the risk of saying stuff you already know (do check the last paragraph for something you might not): Quantum key exchange (only one of the applications of "quantum internet") is completely orthogonal to post quantum encryption. Quantum key exchange is a way to distribute keys, which will be used in so…

No. I think that is the exact point he was making that quantum key distribution is orthogonal to post-quantum cryptography and that the consensus is that poat-quantum cryptography will actually be used while quantum key distribution is basically an academic exercise because it doesn't have practical utility for the problem it is attempting to solve.

I am confused. How is "security that does not depend on any 'difficulty' conjectures / information theoretically perfect" not of practical utility?

Re: What the Quantum Internet Has in Store

#12

Post by NoKnowledge » Mon, Oct 29, 2018, 4:24 PM UTC

jillesvangurp wrote: post #10

I'm not an expert on this. Right now this looks like there's lots of stuff for math and physics nerds to get excited about and not much else. Certainly words like "quantum internet" sound like complete bullshit designed separate investors from their cash rather than market any concrete products or solutions. All I'm hearing in terms of practical applications has exclusively to do with hardening cryptography: safer wa…

When quantum computers break existing algorithms, we do not need to resort to quantum key exchange, but we can make the switch to post-quantum crypto, as also indicated by the other comment[0].

However, switching to the next generation of crypto only after the current generation is broken is not a solution. Much data needs to be kept secret for a long time. Internet traffic is currently being stored so that when the current crypto is broken all data can be decrypted retroactively.

[0]: https://news.ycombinator.com/item?id=18327175

Re: What the Quantum Internet Has in Store

#13

Post by NoKnowledge » Mon, Oct 29, 2018, 4:29 PM UTC

krastanov wrote: post #11

bloomer wrote: post #8

Earlier quoted context omitted.

No. I think that is the exact point he was making that quantum key distribution is orthogonal to post-quantum cryptography and that the consensus is that poat-quantum cryptography will actually be used while quantum key distribution is basically an academic exercise because it doesn't have practical utility for the problem it is attempting to solve.

I am confused. How is "security that does not depend on any 'difficulty' conjectures / information theoretically perfect" not of practical utility?

The so called quantum key-exchange requires a shared secret, so it is actually doing key-expansion. Besides that it has practical problems in side-channel protection and cannot achieve a high enough bandwidth to be of interest in most practical settings.

Re: What the Quantum Internet Has in Store

#14

Post by roywiggins » Mon, Oct 29, 2018, 4:46 PM UTC

NoKnowledge wrote: post #13

krastanov wrote: post #11

Earlier quoted context omitted.

I am confused. How is "security that does not depend on any 'difficulty' conjectures / information theoretically perfect" not of practical utility?

The so called quantum key-exchange requires a shared secret, so it is actually doing key-expansion. Besides that it has practical problems in side-channel protection and cannot achieve a high enough bandwidth to be of interest in most practical settings.

If you wanted to toss out public key cryptography as insecure, I guess you could use QKE to make symmetric key cryptography more practical. You would have a secure method of communicating your keys, and wouldn't have to worry that your new post-quantum public key cryptography was broken- since symmetric cryptography just isn't vulnerable in the same way.

Re: What the Quantum Internet Has in Store

#15

Post by roywiggins » Mon, Oct 29, 2018, 4:47 PM UTC

CiPHPerCoder wrote: post #9

krastanov wrote: post #7

Earlier quoted context omitted.

I think you are conflating two similarly named topics, or at least missing the point of why one of them is useful. At the risk of saying stuff you already know (do check the last paragraph for something you might not): Quantum key exchange (only one of the applications of "quantum internet") is completely orthogonal to post quantum encryption. Quantum key exchange is a way to distribute keys, which will be used in so…

To be honest, the only application for quantum entanglement I'm excited about is quantum teleportation.

Quantum teleportation is only useful for moving entangled states around- it's not actually useful in and of itself unless you have some other application for entanglement in mind.

Re: What the Quantum Internet Has in Store

#16

Post by krastanov » Mon, Oct 29, 2018, 6:09 PM UTC

NoKnowledge wrote: post #13

krastanov wrote: post #11

Earlier quoted context omitted.

I am confused. How is "security that does not depend on any 'difficulty' conjectures / information theoretically perfect" not of practical utility?

The so called quantum key-exchange requires a shared secret, so it is actually doing key-expansion. Besides that it has practical problems in side-channel protection and cannot achieve a high enough bandwidth to be of interest in most practical settings.

Edit: Deleted an incorrect comment. This is a good description of what I am missing: https://crypto.stackexchange.com/questions/2719/is-quantum-k... (man in the middle attacks)

Re: What the Quantum Internet Has in Store

#17

Post by marcosdumay » Mon, Oct 29, 2018, 6:38 PM UTC

krastanov wrote: post #7

CiPHPerCoder wrote: post #3

> The first—which they say is a sort of stage 0 because it does not describe a true quantum internet—is a network that enables users to establish a common encryption key, so that they can share their (classical) data securely. The quantum physics occurs only behind the scenes: the service provider uses it to create the key. But the provider also knows the key, which means that users have to trust it. I don't like whe…

I think you are conflating two similarly named topics, or at least missing the point of why one of them is useful. At the risk of saying stuff you already know (do check the last paragraph for something you might not): Quantum key exchange (only one of the applications of "quantum internet") is completely orthogonal to post quantum encryption. Quantum key exchange is a way to distribute keys, which will be used in so…

Well, let's go...

> Quantum key exchange is a way to distribute keys, which will be used in some symmetric encryption scheme

The largest use of an asymmetrical cryptographic algorithm is key distribution, for use with a symmetric algorithm.

> That scheme has security that does not depend on any "difficulty" conjectures. It is "information theoretically perfect" modulo implementation bugs.

Up to this point, I've never seen any design of quantum encryption that provides any actual security. It's an abstract property of them that there should be one way to get physical security, just like it's a property of computing that there should be some good NP-hard problem one can base a cryptographic algorithm on. AFAIK, both are open problems.