SHORT-DISTANCE APPLICATIONS OF QUANTUM CRYPTOGRAPHY

We present an identification protocol based on quantum mechanics. The first user, Alice, needs to identify herself in front of a second user , Bob, by means of a password, known only to both. The safety requirem ent for Alice is that somebody impersonating Bob, who only pretended t o know Alice's password, shall not be able to obtain information on th e password from the exchange. This is an example of a potentially prac tical new application of quantum mechanics to cryptography.