Physicists Develop Quantum Public Key Encryption
“The problem with public key encryption schemes is that although classical computers cannot factorise big numbers quickly, quantum computers can. So as soon as the first decent-sized quantum computer is switched on, these kinds of systems will become insecure.
Today, Akinori Kawachi at the Tokyo Institute of Technology in Japan and a few buddies suggest that all is not lost for public key encryption. These guys have discovered a quantum problem that is hard to solve in one direction but easy to do in reverse. And they say this asymmetry could form the basis of a new kind of quantum public key encryption system.
Their system is based on the problem of distinguishing between two ensembles of quantum states. This is similar to the problem of determining whether two graphs are identical, ie whether they correspond vertex-for-vertex and edge-for-edge.”