Thermal Noise makes Quantum Cryptography obselete?

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.

Published by

Daniel Lemire

A computer science professor at the University of Quebec (TELUQ).

Leave a Reply

Your email address will not be published. Required fields are marked *

To create code blocks or other preformatted text, indent by four spaces:

    This will be displayed in a monospaced font. The first four 
    spaces will be stripped off, but all other whitespace
    will be preserved.
    Markdown is turned off in code blocks:
     [This is not a link](

To create not a block, but an inline code span, use backticks:

Here is some inline `code`.

For more help see