Importance & hidden story of Quantum Cryptography

-Gilles Brasard-
Quantum cryptography is the only approach to privacy ever proposed that allows two parties (who do not share a long secret key ahead of time) to communicate with provably perfect secrecy under the nose of an eavesdropper endowed with unlimited computational power and whose technology is limited by nothing but the fundamental laws of nature.

The funny thing is that, while our theory had been serious, our prototype was mostly a joke. Indeed, the largest piece in the prototype was the power supply needed to feed in the order of one thousand volts to Pockels cells, used to turn photon polarization. But power supplies make noise, and not the same noise for the different voltages needed for different polarizations. So, we could literally hear the photons as they flew, and zeroes and ones made different noises. Thus, our prototype was unconditionally secure against any eavesdropper who happened to be deaf !

Wiesner submitted his paper “Conjugate Coding” to the IEEE Transactions on Information Theory. Unfortunately, it was rejected, probably deemed incomprehensible by the editors and referees because it was written in the technical language of physicists (which must have seemed normal for a physicist!). It is fortunate that Wiesner had expounded his ideas to Bennett, for they might otherwise have been lost forever