Patent ID: 8126146

Claim:
A quantum cryptography method having multiple stages, comprising the steps of: 1) a receiver rotating polarization of a single photon or a photon flux by an arbitrary angle .psi. and transmitting it to a transmitter, 2) the transmitter rotating the polarization of the single photon or the photon flux received from the receiver by an arbitrary angle .theta. and transmitting it to the receiver, 3) the receiver rotating the single photon or the photon flux received from the transmitter by an arbitrary angle .phi., and transmitting it to the transmitter, 4) the transmitter rotating the single photon or the photon flux received from the receiver by —.theta. and then by an angle corresponding to information bit “ 1 ” or “ 1 ”, and transmitting it to the receiver, 5) the receiver rotating the single photon or the photon flux rived from the transmitter by —(.psi.+.phi.) and finally acquiring an information signal by reading the angle corresponding to information bit “ 0 ” or “ 1 ”, 6) the transmitter acquiring a hash value of transmitted information using a pre-determined hash function, and the receiver determining a hash value of received information, 7) the transmitter determining whether the transmitted information is delivered without error by comparing the acquired hash value with the hash value received from the receiver, and 8) the receiver acquiring the hash value of the received information using a pre-determined hash function, and determining whether an information bit received by itself is erroneous by comparing them with each other.