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Quantum Cryptography Hailed to be Unbreakable  (Source: BBC News)
Quantum encryption uses photons to deliver encryption keys

Data security is paramount in today's sensitive business environments. Hackers today can get into networks that store financial data like bank accounts or credit card numbers and make off with millions in stolen property.

Encryption is used on most networks that store this sort of data, but encryption is not unbreakable. A new form of encryption has been introduced at a scientific conference in Vienna. According to BBC News, the new encryption method is called quantum cryptography and it's unbreakable.

A demonstration of the quantum cryptography system was performed on a network connecting six locations around Vienna. The locations were connected using standard fiber optic cable. The quantum cryptography was devised by Charles Bennett of IBM and Gilles Brassard of Montreal University.

The basis for the cryptographic system is described by Brassard, "All quantum security schemes are based on the Heisenberg Uncertainty Principle, on the fact that you cannot measure quantum information without disturbing it."

He continued telling BBC News, "Because of that, one can have a communications channel between two users on which it's impossible to eavesdrop without creating a disturbance. An eavesdropper would create a mark on it. That was the key idea."

The system sends faint beams of light containing single photons fired a million times per second from which a numerical key can be recovered. The advantage of the system is that if anyone eavesdrops on the communication between nodes the key is disturbed and the node shuts down. At the same time the hacked node shuts down the network is routed to another node to keep it running.

Two different methods are available to send the encryption key in the quantum system. One looks at the direction the photons are polarized and the other looks at the precise timing of the arrival of the photons. Any network using quantum cryptography put into use would have to be able to work with both types of encryption methods.

Dr. Hans Huebel from the Vienna University said, " We are constantly in touch with insurance companies and banks, and they say it's nearly better that they lose 10 million euros than if the system is down for two hours, because that might be more damaging for the bank. So that's what we have to prove, that we have a reliable system that delivers quantum keys for several weeks without interruption, and then they might be more interested."

DailyTech first reported on quantum computers for cryptography in August of 2007.



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RE: not impossible to eavesdrop
By quickk on 10/9/2008 6:46:16 PM , Rating: 3
The point of quantum encryption schemes is not to make it impossible to eavesdrop, but to make it impossible to eavesdrop without being detected. So yes, it would be possible for an opponent to listen in on your transmission and eventually get enough info to determine its contents, but you would know that it happened.


RE: not impossible to eavesdrop
By Master Kenobi (blog) on 10/9/2008 8:21:48 PM , Rating: 2
I disagree, as a signal is passed through devices normally, it can be recorded and it should not impact it at all. How the hell does the encryption stream know that I'm committing itself to disk while I pass it on? It can't.


RE: not impossible to eavesdrop
By Master Kenobi (blog) on 10/9/2008 8:27:07 PM , Rating: 2
I will clarify, while their demonstration showed that attempts to intercept it were noticed due to a degredation in the signal thus altering it, I can't imagine that there is no way to "listen in" while the traffic flows freely. I don't doubt that the encryption it uses might be unbreakable(for the moment), but not being able to intercept and record the packet stream seems quite impossible even when you consider quantum mechanics.

Rule #1- The minute you say something can't be done, it sets in motion the determination for someone to figure out just how to do it. Humans have been doing this forever.


RE: not impossible to eavesdrop
By NarcoticHobo on 10/11/2008 2:41:29 AM , Rating: 2
While I agree with your Rule #1 I don't think you quite understand the principle of quantum mechanics this works under.

With the Heisenberg Uncertainty principle the act of observing something irrevocably changes it. So yes if you are recording something to disk it would "know" you were doing so.

It's like Schrodinger's cat, set up the system where a cat in a box has a 50% chance of dying upon pressing a button. After pressing the button the cat exists in the box as both alive and dead, and only by opening the box does it become one or the other. This is a difficult concept to comprehend because it requires grasping that an object can exists in two states simultaneously, and that somehow simply observing that object causes it to cease being in dual state form.

The only way around this would be to somehow observe it without observing it. Which seems contradictory... but hey, so does being alive and not alive at the same time.


RE: not impossible to eavesdrop
By coolPC on 10/11/2008 1:01:28 PM , Rating: 2
the question is not if the cat is alive or dead. the question is "does the cat exist if it is not observed?"


RE: not impossible to eavesdrop
By quickk on 10/16/2008 4:56:16 PM , Rating: 2
Quantum mechanics is very strange, and is extremely counter-intuitive. While it is easy to record classical information without disturbing or altering it, the same cannot be said for quantum information.

In simplest terms, quantum communication involves the transmission of quantum states which are composed of superpositions of many different possibilities. As soon as you make a measurement on a quantum state, this state collapses into one of the possibilities. The outcome of your measurement will be one of these possibilities (called an eigenstate). Once the measurement is made, you cannot return the quantum state to the way it was before (you don't even know what the different possibilities were---you only got one outcome). The intended recipient will notice that the message had been tampered with because the decryption scheme relies on the fact that the state is still in a superposition of different possibilities.


"There is a single light of science, and to brighten it anywhere is to brighten it everywhere." -- Isaac Asimov

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