METHOD OF TRANSMITTING PRIVATE KEY IN QUANTUM CRYPTOGRAPHIC SYSTEMS Russian patent published in 2010 - IPC H04L9/00 

FIELD: physics; communication.

SUBSTANCE: invention relates to quantum cryptographic systems and can be used for generating private keys used for encrypting information in quantum data transmission systems. To achieve the result, a sequence of separate quantum particles, as well as a first and a second random character string is generated at the transmission side, selection is done in accordance with the value of the subsequent character, quantum state of the quantum particle is modulated, the modulated quantum particle is transmitted over a first quantum communication channel to a first intermediate point, in a second intermediate point, a sequence in mixed up state of quantum particle pairs is generated, the first of which is transmitted over a second quantum communication channel to the first intermediate point and the second - over a third quantum communication channel to the reception side, in the first intermediate point the Bell state of the modulated quantum particle and the first quantum particle of the mixed up pair is measured, the measurement result is transmitted over a second non-secure communication channel to the transmission side, at the reception side a third random character string is generated and transmitted over a first non-secure communication channel to the transmission side, polarisation basis is selected in accordance with the said third random character string and the quantum state of the second quantum particle of the mixed up pair is demodulated, value of the received code character is determined, at the transmission side values of subsequent characters of the second and third random character strings are compared, positions in the first random code character string on which character values of the second and third character strings coincide are determined, for each of the said positions the quantum state of the second quantum particle of the corresponding mixed up pair is determined, private key characters are generated by selecting characters of the first random code character string located in corresponding positions, where values of the selected characters either remain unchanged or are inverted depending on polarisation of the second quantum particle of the corresponding mixed up pair, information on given positions is transmitted over the first non-secure communication channel to the reception side on which private key characters are generated by selecting corresponding received characters of the first random code character string.

EFFECT: increased propagation distance of the private key.

1 dwg, 2 tbl