Atmospheric Turbulence-Controlled Cryptosystems

Ivan B Djordjevic

doi:10.1109/jphot.2021.3053860

Abstract

To overcome the limitations of QKD, post-quantum cryptography, and computational security-based cryptography protocols in this paper, an atmospheric turbulence-controlled cryptosystem is proposed. The proposed encryption scheme employs the traditional scheme to utilize the atmospheric turbulence as the common source of randomness only in the initialization stage to determine the common parameters to be used in the proposed encryption scheme. To overcome low secret-key rates of traditional scheme, dictated by the long coherence time Tc of turbulence channel, the proposed encryption scheme updates the parameters of gamma-gamma distribution, used to generate irradiance samples for cumulative distribution function-based determination of the key, every Tc seconds and as such the final key is shaped by the atmospheric turbulence channel. We also describe a scheme that randomly selects one of several available paths in which the simultaneously measured irradiance samples, after interleaving, are used to generate the raw key. The secret-key rates of the proposed schemes are orders of magnitude higher compared to corresponding traditional QKD and source type physical-layer security schemes and are comparable with the state-of-the-art optical communication data rates.

Highlights

The quantum key distribution (QKD) employs the concepts from quantum information theory, in particular no-cloning theorem and theorem on indistinguishability of arbitrary quantum states, to realize the distribution of keys whose security is guaranteed by the fundamentals physics’ laws [1]–[4], rather than unproven mathematical assumptions used in computational security [5], [6]
To overcome low secret-key rates of traditional scheme, dictated by the long coherence time Tc of turbulence channel, the proposed encryption scheme updates the parameters of gamma-gamma distribution, used to generate irradiance samples for cumulative distribution function-based determination of the key, every Tc seconds and as such the final key is shaped by the atmospheric turbulence channel
Given the low raw key rates, dictated by long coherence time of atmospheric turbulence channels for source type secret-key generation (SKG) protocols, we propose to employ the atmospheric turbulence measurements as a source of randomness only to initialize the corresponding SKG protocol, while adjusting the parameters of the protocol based on time-varying free-space optical (FSO) channel conditions

Summary

Introduction

The quantum key distribution (QKD) employs the concepts from quantum information theory, in particular no-cloning theorem and theorem on indistinguishability of arbitrary quantum states, to realize the distribution of keys whose security is guaranteed by the fundamentals physics’ laws [1]–[4], rather than unproven mathematical assumptions used in computational security [5], [6]. The secret-key rate (SKR) and achievable distance are both limited by the channel loss, which is dictated by the rate-loss tradeoff To overcome these problems, among others, the following two approaches have become relevant: (i) introduction of the trusted relays concept [7] and (ii) quantum relays development [8]. Given the low raw key rates, dictated by long coherence time of atmospheric turbulence channels for source type secret-key generation (SKG) protocols, we propose to employ the atmospheric turbulence measurements as a source of randomness only to initialize the corresponding SKG protocol, while adjusting the parameters of the protocol based on time-varying FSO channel conditions.

Description of Proposed Atmospheric Turbulence-controlled SKG Protocol

The Model and Illustrative Numerical Results

Concluding Remarks