PROTECTION PROBLEM OF SYNCHRONIZATION FROM UNAUTHORISED ACCESS IN QUANTUM KEY DISTRIBUTION SYSTEM
The paper analyzes the problem of providing security against unauthorized access to synchronization process in autocompensation quantum key distribution system with phase coding states of photons. The commercial quantum key distribution system with automatic compensation of polarization distortions, which operates on the principle of «plug&play» are researched. The process of synchronizing the two stations of quantum key distribution system are analyzed. The block diagram of the propagation of optical radiation, which operates on single fiber autocompensation scheme are showed. The basic methods of attacks on the quantum communication channel during synchronization in quantum key distribution system are proposed. The description of the developed synchronization algorithm with improves protection from unauthorized access and reducing the probability of making a wrong decision in the process of detecting the photons are proposed. The algorithm involves finding a signal time window containing the photon momentum. A distinctive feature of the algorithm is that the propagation direction of the optical signal from the encoding station to the transceiver carried attenuation until photon level, the average number of photons per pulse is not more than 0.1.