Patent ID: 6748083
Filing Date: 2004-06-08
Classification: H04B,H04L

Abstract:
Apparatus for securely generating a key to be used for secure transmission between a sender and a receiver connected by an atmospheric transmission link, comprising:at least one first laser for outputting a timing bright light pulse; a second laser for outputting a first polarized optical data state; a third laser for outputting a second polarized optical data state; a random bit generator for randomly enabling either the second laser or the third laser; output optics effective to transmit output light from the first, second, and third lasers; receiving optics effective to receive output light of the output optics from the first, second, and third lasers; a first beam splitter for receiving light from the receiving optics, where a received timing bright light pulse is directed to a delay circuit for establishing a window for receiving light from the second or third lasers and where an optical data state from either the second or third laser has a probability of being either transmitted by the beam splitter or reflected by the beam splitter; a first polarizer for receiving transmitted optical data states to output one data bit value; a second polarizer for receiving reflected optical data states to output a second data bit value; and a computer receiving pulses representing receipt of a timing bright light pulse and the first and second data bit values, where receipt of the first and second data bit values is indexed by the timing bright light pulse.