The New Scientist (and slashdot) reports that a very simple method that basically achieves what million-dollars Quantum Cryptography set out to achieve: unbreakable two-way communication. This is due to Laszlo Kish. His papers are on arxiv and they appear pretty convincing, but I have left the world of Physics a long time ago.
Bruce Schneier describes it in those terms:
How would you feel if you invested millions of dollars in quantum cryptography, and then learned that you could do the same thing with a few 25-cent Radio Shack components?
And he concludes:
Basically, if Kish’s scheme is secure, it’s superior to quantum communications in every respect: price, maintenance, speed, vibration, thermal resistance and so on.
Is this true? Is Quantum Cryptography obselete?
There seems to be theoretical difficulties with Kish’s approach, but his experiments seem to suggest that he got it right.