Quantum method of secure key distribution in optical fiber communication lines

The possibility of using photon counters based on avalanche photodiodes to implement a quantum system for key distribution is shown. The security of encryption key distribution is realized with application of eavesdropper detection technique. The detection technique uses quantum control signal. The structural scheme of the quantum system is presented. The effect of photodetector parameters and the length of optical fiber on the eavesdropper detection time have been determined. The conditions and characteristics of the system to organize a secure channel for generation and transfer of encryption keys over optical fiber communication lines have been determined.

I. Introduction

Quantum key distribution is the latest technology that solves the problem of key distribution for symmetric encryption systems using optical fiber as the propagation medium [1]–[3]. The systems of quantum key distribution offered now in the market implement a protocol stack, which consists of both information transfer protocol by single photons, and procedures realizing privacy amplification. These procedures allow to distribute securely an encryption key even in the presence of unauthorized connection to a communication channel if the level of the errors generated by interception in the channel does not exceed some threshold. However, these systems are intended to distribute keys between single pairs of users and have a high market value.