Quantum Public Key Distribution System
Original Publication Date: 1985-Dec-01
Included in the Prior Art Database: 2005-Feb-19
If two users possess shared random secret key information, they can achieve, with provable security, two of the chief benefits of cryptography: 1) making their messages unintelligible to an eavesdropper (one-time-pad encryption achieves this), and 2) distinguishing legitimate messages from forged or altered ones (Wegman-Carter authentication tags suffice to do this). Unfortunately, both one-time-pad encryption and Wegman-Carter authentication consume key information and render it unfit for re-use. Therefore, some secure means of distributing fresh key information is needed. In this invention, faint pulses of polarized light are used to distribute key information via a low-attenuating (10-20 dB), non- depolarizing optical channel, called the "quantum channel".