Vulnerability of the Synchronization Process in the Quantum Key Distribution System

Vulnerability of the Synchronization Process in the Quantum Key Distribution System

A. P. Pljonkin (Southern Federal University, Taganrog, Russia)
Copyright: © 2019 |Pages: 9
DOI: 10.4018/IJCAC.2019010104


A typical structure of an auto-compensation system for quantum key distribution is given. The principle of operation of a fiber-optic system for the distribution of quantum keys with phase coding of photon states is described. The operation of the system in the synchronization mode and the formation of quantum keys was investigated. The process of detecting a time interval with an optical synchronization pulse is analyzed. The structural scheme of the experimental stand of the quantum-cryptographic network is given. Data are obtained that attest to the presence of a multiphoton signal during the transmission of sync pulses from the transceiver station to the coding and backward direction. The results of experimental studies are presented, which prove the existence of a vulnerability in the process of synchronization of the quantum key distribution system. It is shown that the use of a multiphoton optical pulse as a sync signal makes it possible for an attacker to unauthorized access to a quantum communication channel. The experimental results show that tapping a portion of the optical power from the quantum communication channel during the synchronization process allows an attacker to remain unnoticed while the quantum protocol is operating. Experimentally proved the possibility of introducing malfunctions into the operation of the quantum communication system at the stage of key formation, while remaining invisible for control means.
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2. Quantum Key Distribution Systems

In 2007, the methods of quantum cryptography were first applied in a large-scale project. Quantum security system, developed by the Swiss company idQuantique, was used to transmit voting data at the parliamentary elections in Geneva. To date, really functioning quantum communication systems have been created. The efforts of developers are now aimed at increasing the communication range, increasing the speed of forming a quantum key, improving the characteristics of fiber-optic components.

As noted earlier, a symmetric cryptosystem generates a shared secret key and distributes it among legitimate users to encrypt and decrypt messages (Rumyantsev & Pijokin, 2015) . An attacker attempting to investigate transmitted data can’t measure photons without distorting the original message. The system on the open channel compares and discusses signals transmitted on the quantum channel, thereby verifying them for the possibility of interception. If the system does not contain errors, then the transmitted information can be considered securely distributed and secret, despite all the technical capabilities that a cryptanalyst can use.

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