Skip to comments.Noise keeps spooks out of the loop (Developer claims it's better than quantum cryptography)
Posted on 05/26/2007 6:26:09 PM PDT by LibWhacker
SPYING is big business, and avoiding being spied on an even bigger one. So imagine if someone came up with a simple, cheap way of encrypting messages that is almost impossible to hack into?
American computer engineer Laszlo Kish at Texas A&M University in College Station claims to have done just that. He says the thermal properties of a simple wire can be exploited to create a secure communications channel, one that outperforms quantum cryptography keys.
His cipher device, which he first proposed in 2005, exploits a property called thermal noise. Thermal noise is generated by the natural agitation of electrons within a conductor, which happens regardless of any voltage passed through it. But it does change depending on the conductor's resistance.
Kish and his collaborators at the University of Szeged in Hungary say this can be used to securely pass information, or an encryption key, down any wire, including a telephone line or network cable. 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. A quarter of the time they will both choose the high resistor, producing a lot of noise on the line, while a quarter of the time they will both choose the low resistor, producing little noise. If either detect a high or a low amount of noise in the line, they ignore any communication.
Half the time, however, they will choose differently, 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 (http://www.arxiv.org/abs/physics/0612153).
That message is also secure. For a start, as Kish notes, it takes an "educated eavesdropper" to even realise information is being sent when there seems to be just low-level noise on the line. If they do try to eavesdrop, they can only tell a message is being sent, not what it is, because it's impossible to tell whether Alice has a high or low resistor turned on, and whether the bit of information is a 1 or a 0. What's more, eavesdropping on the line will naturally alter the level of thermal noise, so Alice and Bob will know that someone is listening in.
Kish and his team have now successfully built a device that can send a secure message down a wire 2000 kilometres long, much further than the best quantum key distribution (QKD) devices tried so far. Tests show a signal sent via Kish's device is received with 99.98 per cent accuracy, and that a maximum of just 0.19 per cent of the bits sent are vulnerable to eavesdropping. The error rate is down to the inherent resistance of the wire, and choosing a larger wire in future models should help reduce it further. "A secure message can be sent down a wire 2000 kilometres long"
However, this level of security already beats QKD. What's more, the system works with fixed lines, rather than the optical fibres used to carry photons of light at the heart of quantum encryption devices. It is also more robust, as QKD devices are vulnerable to corruption by dust, heat and vibration. It is also much cheaper. "I guess it's around a hundred dollars, at most," Kish says.
"This is a system that should be taken seriously," says security specialist Bruce Schneier, who founded network security firm BT Counterpane. He says he was seduced by the simplicity of the idea when it was first proposed by Kish, and now wants to see independent tests of the working model. "I desperately want someone to analyse it," he says. "Assuming it works, it's way better than quantum."
Z Group won't like this.
Garde la Foi, mes amis! Nous nous sommes les sauveurs de la République! Maintenant et Toujours!
(Keep the Faith, my friends! We are the saviors of the Republic! Now and Forever!)
LonePalm, le Républicain du verre cassé (The Broken Glass Republican)
Amateurs. I just Planck my quantum foam through the pre-determined aperture and after delivery - it dissappears on its own. Nothing could be simpler. Hackproof.
The article doesn’t mention if this will work over a routed network. If it does, once authentication is performed, it seems to me to be extremely secure.
I don’t see how it would work over a router though if the packets are secured by noise.
This seems to have a fundamental problem to me. It seems to depend on two users sharing a common direct hardwired connection. That way they both see the same thermal noise on the line. But suppose each connects to the other through a series of intermediate stops, such as you see on the internet. Then you simply dont see the same line noise and this system would seem to fall apart. What am I missing?
I thought this was an article about housing discrimination in Chicago.
The pure randomness of electronic noise patterns would be orders of magnitude more difficult to crack than 128bit encryption is today. Check it out -- why don't we just encrypt all TCP/IP packets on all overseas routed fiber multiplexes - it would prevent terrorists in countries outside the encrypted networks from easily abusing the open internet to plan and execute attack missions.
Instead of transmitting anything, it sounds like he’s exploiting a physical property of the line to communicate a passkey. (?)
Still, a signal is a signal. I could wave across the street to my neighbor while on the telephone, or tell him to dial the initial call that way. Nobody tapping our telephone line would hear us waving.
ATTN: SIGINT SECTION
Very good post. I enjoyed that. thanks.