The article is focused on research of an attack on the quantum key distribution system and proposes a countermeasure method. Particularly noteworthy is that this is not a classic attack on a quantum protocol. We describe an attack on the process of calibration. Results of the research show that quantum key distribution systems have vulnerabilities not only in the protocols, but also in other vital system components. The described type of attack does not affect the cryptographic strength of the received keys and does not point to the vulnerability of the quantum key distribution protocol. We also propose a method for autocompensating optical communication system development, which protects synchronization from unauthorized access. The proposed method is based on the use of sync pulses attenuated to a photon level in the process of detecting a time interval with a signal. The paper presents the results of experimental studies that show the discrepancies between the theoretical and real parameters of the system. The obtained data allow the length of the quantum channel to be calculated with high accuracy.

A comparative analysis of 3×3 pixel robust detector and Harris detector in terms of stability and performance detection in case of viewing conditions change caused by the collection and conversion of image cameras presented. The efficiency of detectors was evaluated in terms of the repeatability of feature detection on a different pair of images when the conditions of observation, camera parameters (focal length, aperture size of the lens), camera position relative to the observed scene, scene illumination changes. Simulation results show that a robust detector used under these conditions provides a greater number of stable features of the image detected.

The article contains a computationally effective method for determining averaged distribution of differentials for pseudo-dynamic substitutions PD-Sbox. That opens the possibility of an effective search and synthesis of pseudo-dynamic substitutions PD-sbox with optimal characteristics. Search and further study of cryptographic properties of such substitutions will significantly improve the effectiveness of the pseudo-dynamic substitutions PD-sbox in symmetric cryptoalgorithms.

Paper is focused on problem of robust feature detector performance in case when intensity distribution is uneven over image. Results of feature detector simulation in case of various intensity changes, equations for estimation rate of false alarms and probability of correct detection are presented in paper.