Simple Comm Technique Beats Quantum Crypto

Atario wrote us with a link to a New Scientist article about an innovative new way of encrypting communications. An engineer at Texas A&M may have a way to exploit the thermal properties of a wire to create a secure channel. The result could be an effectively impenetrable way of securing communications, possibly outperforming quantum cryptography keys. "In their device, both the sender Alice and the receiver Bob have an identical pair of resistors, one producing high resistance, the other low resistance. The higher the total resistance on the line, the greater the thermal noise. Both Alice and Bob randomly choose which resistor to use ... Half the time ... they will choose different [resistances], producing an intermediate level of thermal noise, and it is now that a message can be sent. If Bob turns on his high resistor, and records an intermediate level of noise, he instantly knows that Alice has chosen her low resistor, in essence sending a bit of information such as 1 or 0. Kish's cipher does this many times, sending a random series of 1s and 0s that can form the basis of an encryption key, the researchers say."

Comments

PAIRS of resistors

[Etherwalk]

Identical pairs of resistors.

I read it the same way you did at first; it's poorly worded.

This sounds like it's someone trying to think outside the box, given a basic knowledge of quantum cryptography. "Well, what else sort of works like light polarization? What is there that, if intercepted, doesn't give the interceptor any more information than said polarization does in the case of quantum cryptography?"

Of course, one of the advantages of quantum is that you can Detect eavesdroppers, because if they listen to more than a few bits they flip more of your bits than probability would reasonably allow for. It isn't only about how much information the eavesdropper can obtain--it's about whether or not you'll realize they're there.

Impenetrable == Unsinkable

[MajorBlunder]

The result could be an effectively impenetrable way of securing communications, possibly outperforming quantum cryptography keys.

When I read this, I had a flash back to a Dr. Who episode.(paraphrasing)

Army General: Trust me doctor this place is impenetrable.

Doctor: The problem with impenetrable is that it sounds too much like unsinkable.

Army General: Well whats wrong with that?

Doctor: Ask the passengers of the Titanic.

I always get a little bit itchy whenever people start throwing superlatives around like unbreakable, impenetrable, etc. Nature, Human ingenuity, or Human stupidity all have a nasty habit of proving us wrong.

Re:What would this be good for?

[evilviper]

What would this or quantum cryptography be good for in practical terms?

Two offices, say, across town, that want to communicate very securely.

Somebody could simply cut the wire and thus forcing Alice and Bob to [...] not communicate at all.

When would that possibly be a problem? That would basically require some strange situation with a totalitarian government that wants to disrupt communications between two end points, but apparently doesn't actually want to get access to the unencrypted information itself.

If it's just some rival company trying to disrupt service, a line crew goes out, fixes the line, and they're back up and running before they even want/need to change the encryption key.

And what would be the point, since you could just as easily cut the other communications lines (eg. OC3s), the power lines, etc., etc.