Quantum Cryptography Broken, and Fixed

schliz writes in with research out of Sweden in which researchers showed that, looking at a quantum cryptographic system as a whole, it was possible for an eavesdropper to extract some information about the QC key, thus reducing the security of the overall system. The team then proposed a cheap and simple fix for the problem. "The advanced technology was thought to be unbreakable due to laws of quantum mechanics that state that quantum mechanical objects cannot be observed or manipulated without being disturbed. But a research team at Linköping University in Sweden claim that it is possible for an eavesdropper to [get around the limitations] without being discovered. In a research paper, published in the international engineering journal IEEE Transactions on Information Theory (abstract), the researchers propose a change in the quantum cryptography process that they expect will restore the security of the technology."

Comments

So is the cat dead?

[EmbeddedJanitor]

Quantum stuff is so illogical to us mortals that you'd expect attempting to break it would just make it stronger.

Re:So is the cat dead?

[Tackhead]

> Quantum stuff is so illogical to us mortals that you'd expect attempting to break it would just make it stronger.

Which is precisely what happened.

In a research paper, published in the international engineering journal IEEE Transactions on Information Theory (abstract), the researchers propose a change in the quantum cryptography process that they expect will restore the security of the technology.

By being sufficiently precise about the nature of the insecurity, they changed the probability of its being insecure!

Furthermore, now that we know it's secure again (that is, we've proven it to be secure, effectively computing the probability of insecurity to be precisely zero), we no longer know anything about the nature of the system's security holes again!

That was all supposed to be a lead-up to a Heisenberg Uncertainty Principle joke, but it's actually a pretty good description of how computer security works in even the non-quantum world. The more secure you think your system is, the more likely it is you'll get 0wn3d in some completely unexpected way. The known unknowns aren't the ones you've gotta worry about, and nailing them down doesn't do anything about the unknown unknowns, other than to collapse the joke's waveform into something resembling a Don Rumsfeld speech.

In anything other than a Slashdot quantum crypto discussion, that sort of whiplash-inducing change of joke subjects would be highly improbable. As it stands, I'm going to shift gears a third time and hand it off to Douglas Adams.

Zaphod: Tackhead, is this sort of thing going to happen every time you post using the Infinite Improbability joke drive?
Tackhead: Very probably, I'm afraid.

Re:So is the cat dead?

[NotQuiteReal]

You can increase the complexity by using a tri-state cat.

It can be either alive or dead or both alive and dead.

We call these three states alive, dead and zombie.

There, I hope that sheds some photons on the matter.

Re:So is the cat dead?

[tzanger]

I thought a tri-state cat would be alive, dead and high-impedance.

Re:So is the cat dead?

[bh_doc]

*sigh* Dude, the whole point of the bi-state cat is that both alive and dead is exactly the state the cat ends up in. It's a superposition until you measure it. That's why it's so bizarre. Schrodinger's cat is a zombie.

Re:So is the cat dead?

[Thanshin]

The tri-state cat should be alive, dead or dog.

Re:So is the cat dead?

[evanbd]

To quote one of my favorite games:

The cat looks up at you and, noticing a certain hungry gleam in your eye that it doesn't like one bit, jumps from the divan and hides in a box under the coffee-table. Just before the lid clicks shut, you see a tiny pendulum inside, and wonder if the cat's going to be alive for much longer. You reason that, since the cat could be either alive or dead, and you can't know which without opening the box, then therefore the cat must be both alive and dead -- or in other words, undead. That must be what funerals are for -- so that everyone knows for certain that the person going into the coffin is definitely dead, and you don't have to worry about quantum uncertainty causing zombies to burst out of the ground.

Re:So is the cat dead?

[caveman]

There is yet another state that the cat can be in, as alluded to in 'Lords and Ladies' by Terry Pratchett..

From Wikipedia:

Greebo had spent an irritating two minutes in that box. Technically, a cat locked in a box may be alive or it may be dead. You never know until you look. In fact, the mere act of opening the box will determine the state of the cat, although in this case there were three determinate states the cat could be in: these being Alive, Dead, and Bloody Furious.

Shawn dived sideways as Greebo went off like a Claymore mine.

"Don't worry about him," said Magrat dreamily, as the elf flailed at the maddened cat. "He's just a big softy."

I know the solution

[jollyreaper]

They were connecting the computers via cat-5 cable. Everyone knows you're supposed to use Schrödinger's cat-5 cable in that sort of application.

That wacky quantum cryptography

[Anonymous Coward]

It was actually broken AND fixed at the SAME TIME!

Re:That wacky quantum cryptography

[mrbluze]

It was actually broken AND fixed at the SAME TIME! Kind of like a Windows Update.

Re:Wah?

[dotancohen]

Again in English please? It just means that they were using Debian.

Re:One time pad

[dotancohen]

Just use a one time pad. That way she won't know where to find you when he wants his daddy?

Spooky Decryption

[bevoblake]

It's quantum right? So there's really just a probability of it being broken or fixed at any given point in time...

Oh,

[oliverk]

What's really going to bake your noodle later on is, would you still have broken it if I hadn't said anything?

Alice and Bob are sick today. We need some answers

[failedlogic]

As I don't know what I'm supposed to know about quantum cryptography, where can I find Alice and Bob to explain it to me? I feel sorry for them though. I'm always bugging them for an explanation and they always oblige. I'm really pissed off though. Every time, I want a different opinion, there they are in every book - Alice .... and .... Bob. Why must *they* always explain to me the most difficult concept in computing. If they aren't doing their jobs, as is obvious with QC, we need some new instructors. If I were either of them, I'd quit my day job. Since nobody understands QC, and anyone that does can't simplify it for the rest of us, they're setting themselves up for massive overtime or heart attack.

Re:There is no such thing as absolute security

[Anne_Nonymous]

If you love your data, let it go. If it returns to you, it's yours.

Re:The End of The Science of Cryptography

[Tmack]

...It will never be applied to cat 5 LANs....

Unless of course (as was pointed out above), that lan is using Shrödinger's cat-5...

tm

Re:Fundamental Flaw in Quantum[Anything]

[nerdacus]

Someone's beliefs are at odds with well founded, empirically established physical laws?! I just hope this doesn't catch on..

Too late, it caught on long ago. It's called religion.