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

Article is a dupe...

[The Master Control P]

Just like the last time, the laws of quantum physics still work and it is still impossible to observe a quantum system without altering it. The researchers found that the classical authentication protocols that prevent man-in-the-middle attacks were insufficient.

The End of The Science of Cryptography

[Whiteox]

There was an interesting book on cryptography which I loaned to a friend, that surmised that the law of cryptography which state that every code can be broken is now defunct due to quantum cryptography.
This in effect means that the science of cryptography has met its end in terms of development.
Like the game of checkers, there are no more moves to make.
At the time of publication (2002?), the longest distance an encrypted quantum message sent and received was approximately 50kms and considered to be impossible to break.

Re:Wah?

[catprog]

The thing is you can only accurately read about 50% of the photons.

When Eve reads the message changes to 50% correct, 50% incorrect.

When Bob gets the photons his 50% will consist of 25% correct and 25% incorrect ones. (assuming true randomness)

When Alice and Bob compare there keys they will see the discrepancy.

Then the 1 and 0 are XORs with the message and then the result is sent.

http://en.wikipedia.org/wiki/Quantum_cryptography#Polarized_photons_-_Charles_H._Bennett_and_Gilles_Brassard_.281984.29