Secure Communication System Research Articles

Private correlated random bit generation based on synchronized wideband physical entropy sources with hybrid electro-optic nonlinear transformation.

We propose and experimentally demonstrate a novel, to the best of our knowledge, private correlated random bit generation (CRBG) scheme based on commonly driven induced synchronization of two wideband physical entropy sources, which employs an open-loop distributed feedback laser followed by a hybrid electro-optic nonlinear transformation hardware module for effective bandwidth expansion and privacy enhancement. A Mach-Zehnder interferometer followed by an electro-optic self-feedback phase modulation loop as well as a dispersion element are constructed as a private hardware module to perform post-processing and nonlinear transformation of the synchronized signal. A record high rate of 5.2-Gb/s CRBG is successfully achieved between two synchronized wideband physical entropy sources with an enhanced entropy source rate and hardware key space. The demonstrated scheme may provide a new way for CRBG in future high speed secure communication systems.

Multi-dimensional disturbance secure communication system with dynamic key hiding transmission based on power-domain non-orthogonal multiple access

Data security is becoming more critical in networks as high-speed and large-capacity optical transmission becomes more common. Cryptographic protocols at the MAC layer and higher tiers of the protocol stack are under threat as a result of quantum computer developments. Optical physical layer encryption has great advantages in optical communication security transmission, which can be compatible with a variety of networks, and achieve an efficient and secured ultra-high high-speed data transmission. In this work, we propose a physical layer encryption scheme based on orthogonal frequency division multiplexing power-domain non-orthogonal multiple access (OFDM-PD-NOMA) technique for the dynamic key hiding transmission and multi-dimensional disturbance. The encryption scheme realizes multi-point mutual-coupling key transmission and multi-dimensional disturbance encryption by a 3D discrete chaotic model. The encrypted data and the dynamic key are transmitted together by multichannel signals in PD-NOMA, then, the chaotic signal generated by chaotic generator is used to mask the dynamic key. 3D chaotic sequences generated by the dynamic key are used to encrypt bits, symbols and carriers of the original signal. The initial key, the dynamic key and the chaotic signal realize multi-point mutual-coupling. We conduct a 74.6 Gb/s encrypted quadrature phase shift keying (QPSK)-OFDM-PD-NOMA signal transmission over 2 km 7 core fiber. The key space of encrypted scheme can reach 10462. Finally, experimental results show that the original data can be recovered accurately, and the bit error rate (BER) of the dynamic key is close to zero. The security and reliability of the system have been verified, and this scheme has an important application prospect in the future optical communication system.

Artificial intelligence technology in electronic communication engineering for medical applications

In order to solve the problem of high frame error rate in electronic communication engineering, the application of artificial intelligence technology in electronic communication engineering is proposed. Taking LPWAN technology in artificial intelligence technology as an example, a new architecture is proposed to improve the security of wireless communication system of internet of things. The architecture is mainly composed of business layer, data processing layer, terminal access layer and communication technology layer. The experimental results show that the system configuration sends four kinds of information transmission instructions of “temperature, light, air pressure and humidity” every 30 s, and the receiving port collects the above command data continuously for 4 h, compared with the traditional architecture (15.6%), and the packet loss rate is 4%, which can effectively improve the throughput and processing efficiency of the system. The designed architecture runs stably, has low bit error rate, and can better support the wireless communication. It is proved that the new architecture with LPWAN technology as an example has large overall capacity and excellent performance of its electronic communication engineering interface. The frame number error rate is greatly reduced and the result of signal frame number is more accurate.

Providing Physical Layer Security for IoTs in the Last Mile

Communication security is one of the top security challenges for connected devices. Different from other links such as backhaul, the last mile technology also depends on the requirements of end users. Wireless technologies are generally selected for the mobility of users and ease of use. However, wireless medium has an open nature and thus wireless links are more prone to physical layer attacks compared to their wired counterparts. Moreover, simple end devices have constrained resources in both hardware and software, and it is not always feasible to apply conventional cryptographic approaches to provide security. We turn to chaos theory to provide security for simple devices at physical layer. The FM-DCSK and FM-CSK transmission system are built and implemented in the proposed secure communication system. The information message is embedded in wideband random-like signals, making the message remain covert. Transmission security is achieved by using the initial conditions and spreading factor as keys. To guard against active attacks, procedures for dynamic adjustment of initial conditions and other parameters are proposed. The scheme's cost effective features include the simplicity of communication setup and the low power consumption in generating and controlling the chaos signal. The sensitivity to initial condition and complex dynamic feature of chaotic function make it a promising approach for physical layer security.

Intelligent blind source separation technology based on OTFS modulation for LEO satellite communication

In LEO (Low Earth Orbit) satellite communication system, the orbit height of the satellite is low, the transmission delay is short, the path loss is small, and the frequency multiplexing is more effective. However, it is an unavoidable technical problem of the significant Doppler effect caused by the interference between satellite networks and the high-speed movement of the satellite relative to the ground. In order to improve the target detection efficiency and system security of LEO satellite communication system, blind separation technology is an effective method to process the collision signals received by satellites. Because of the signal has good sparsity in Delay-Doppler domain, in order to improve the blind separation performance of LEO satellite communication system, orthogonal Time-Frequency space (OTFS) modulation is used to convert the sampled signal to Delay-Doppler domain. DBSCAN clustering algorithm is used to classify the sparse signal, so as to separate the original mixed signal. Finally, the simulation results show that the method has a good separation effect, and can significantly improve the detection efficiency of system targets and the security of LEO satellite communication system network.

A secure and energy efficient key agreement framework for vehicle-grid system

Energy Internet (EI) is a two-way data flow that allows electric service providers and consumers to investigate and change their energy usage. EI should be free of cyber-attacks in order to provide secure, efficient, and dependable communication system operations. Using elliptic curve cryptography and the hash function, this paper proposes a key agreement and authentication framework for vehicular to grid networks. Using key agreement, a vehicular user can securely access services provided by the grid server in this protocol. We also talk about informal security analysis of the proposed protocol which is based on security attacks and security attributes. We show the correctness of the proposed framework through a formal security analysis of the proposed framework using a random oracle model. In addition, we demonstrate that the proposed framework has lower computation and communication costs than other V2G frameworks.

Secure Real-time Data Transmission for Drone Delivery Services using Forward Prediction Scheduling SCTP

Drone technology is considered the most effective solution for the improvement of various industrial fields. As a delivery service, drones need a secure communication system that is also able to manage all of the information data in real-time. However, because the data transmission process occurs in a wireless network, data will be sent over a channel that is more unstable and vulnerable to attack. Thus, this research, purposes a Forward Prediction Scheduling-based Stream Control Transmission Protocol (FPS-SCTP) scheme that is implemented on drone data transmission system. This scheme supports piggybacking, multi-streaming, and Late Messages Filter (LMF) which will improve the real-time transmission process in IEEE 802.11 wireless network. Meanwhile, on the cybersecurity aspect, this scheme provides the embedded option feature to enable the encryption mechanism using AES and the digital signatures mechanism using ECDSA. The results show that the FPS-SCTP scheme has better network performance than the default SCTP, and provides full security services with low computation time. This research contributes to providing a communication protocol scheme that is suitable for use on the internet of drones’ environment, both in real-time and reliable security levels.

Synchronizing chaotic PDE system using backstepping and its application to image encryption

This paper is concerned with the observer design problem for a nonlinear hyperbolic system with a modified van der Pol boundary condition in which an integral term is included. The observer plays a role of a chaotic synchronizing system when applying it to secure communication. In our previous work (Sano et al. Secure communication systems using distributed parameter chaotic synchronization. SICE Trans. 2021;57(2):78–85), a nonlinear hyperbolic system without the integral term was treated and a simple synchronizing system was constructed, where the constant coefficients of system played a role of encryption keys. But the keys were vulnerable from a safety standpoint. On the other hand, in the case where the integral term is included in the boundary condition, we need to construct observers. The weighted function contained in the integral term gives a new encryption key of distributed type. An application to image encryption is also discussed and numerical simulation results are given.

A novel algorithm to analyze the dynamics of digital chaotic maps in finite-precision domain

Chaotic maps are widely used to design pseudo-random sequence generators, chaotic ciphers, and secure communication systems. Nevertheless, the dynamic characteristics of digital chaos in finite-precision domain must be degraded in varying degrees due to the limited calculation accuracy of hardware equipment. To assess the dynamic properties of digital chaos, we design a periodic cycle location algorithm (PCLA) from a new perspective to analyze the dynamic degradation of digital chaos. The PCLA can divide the state-mapping graph of digital chaos into several connected subgraphs for the purpose of locating all fixed points and periodic limit cycles contained in a digital chaotic map. To test the versatility and availability of our proposed algorithm, the periodic distribution and security of 1-D logistic maps and 2-D Baker maps are analyzed in detail. Moreover, this algorithm is helpful to the design of anti-degradation algorithms for digital chaotic dynamics. These related studies can promote the application of chaos in engineering practice.

Performance Evaluation and Security Analysis of UAV-Based FSO/CV-QKD System Employing DP-QPSK/CD

Unmanned aerial vehicles (UAV) based on free-space optical (FSO) systems combine the benefits of both the high data rate of the FSO and the mobility of UAV. However, cumulative effects of laser beam divergence and turbulence-induced fading on the received irradiance in the FSO link might allow an external eavesdropper located near the authorized receiver to break the transmission under certain conditions. Quantum key distribution (QKD) is a technique of secure communication that employs quantum mechanics-based cryptography principles. A combination of a continuous-variable quantum key distribution (CV-QKD) and Gaussian modulation of quantum coherent states (GMCS) enables a relatively secure communication system against collective attacks over FSO transmission links. However, the performance is restricted and degraded due to the influence of atmospheric turbulence and excess noise. This paper aims to evaluate the performance of a secured UAV-based FSO system utilizing prepare and measure CV-QKD protocol based on GMCS under collective attack in terms of quantum bit error rate (QBER), outage probability, and secret key rate (SKR) considering the impairments of the FSO channel, link budget, deviations in the position and attitude angles of the UAV, channel fluctuating transmittance, and excess noise. The system parameters, including transmit power, receiver’s field-of-view, and beam divergence angle, are optimized to satisfy the system’s design criteria of threshold-QBER <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$=10^{-3}$</tex-math></inline-formula> and threshold outage probability <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$=10^{-2}$</tex-math></inline-formula> . The proposed system tolerates boresight displacement up to 7 cm with the optimized values. The Closed-form expressions and analytical results are confirmed by Monte-Carlo simulations.

Synchronizing Analog - Discrete Nonlinear Systems

Abstract Using nonlinear chaotic systems for secure communication is an application field presented in recent published research. This paper aims at improving the security of signal transmission using chaotic encryption. The proposed approach uses a combined analogue and discrete-time structure, for both chaotic emitter and synchronizing receiver. The prototype system used is similar to the Lorenz nonlinear oscillator. Our study presents the emitter dynamic properties, develops the receiver synchronization using the emitter partitioning method, and designs a linear equalizer at the receiving end of the communication chain in order to improve the demodulated signal.

Practical underwater quantum key distribution based on decoy-state BB84 protocol.

Polarization encoding quantum key distribution has been proven to be a reliable method to build a secure communication system. It has already been used in an inter-city fiber channel and near-Earth atmosphere channel, leaving an underwater channel the last barrier to conquer. Here we demonstrate a decoy-state BB84 quantum key distribution system over a water channel with a compact system design for future experiments in the ocean. In the system, a multiple-intensity modulated laser module is designed to produce the light pulses of quantum states, including signal state, decoy state, and vacuum state. Classical communication and synchronization are realized by wireless optical transmission. Multiple filtering techniques and wavelength division multiplexing are further used to avoid cross talk of different lights. We test the performance of the system and obtain a final key rate of 245.6 bps with an average quantum bit error rate of 1.91% over a 2.4 m water channel, in which the channel attenuation is 16.35 dB. Numerical simulation shows that the system can tolerate up to 21.7 dB total channel loss and can still generate secure keys in 277.9 m Jerlov type I ocean channel.

Adaptive symmetry control in secure communication systems

Chaos-based secure communications is a broadly studied field in nonlinear dynamics. Such technique is traditionally based on chaotic synchronization between master and slave systems implemented as the transmitter and receiver. A common way to encode the message is switching the bifurcation parameters of the master system, which leads to perturbation of the dynamics and often breaks the synchronization. The time of the transient process to restore the identity of the trajectories of the master and slave systems can be unacceptably long for practical applications. Therefore, the development of techniques for fast re-synchronization of models of chaotic systems is of interest. In this paper we propose a novel technique for synchronizing finite-difference models of continuous chaotic systems through adaptive control of the so-called symmetry coefficient. We experimentally confirm that the proposed approach can be faster than the traditional control of the bifurcation parameter. In addition, we discovered that changing the symmetry coefficient in semi-implicit models leads only to a slight deformation of the stability regions of the finite-difference scheme and practically does not affect the nonlinear properties of the simulated chaotic system. The applied analysis shows that detecting a transmitted message through the modulation of the symmetry coefficient is difficult compared to the conventional approach.

Real-time fuzzy-pid synchronization of memristor-based chaotic circuit using graphical coded algorithm in secure communication applications

The main goal of this study is to implement real-time synchronization of a memristor-based chaotic circuit for secure communication on LabVIEW virtual instrument environments. Memristors can be used in chaotic circuits because of their nonlinear behavior. In this paper, an application for secure communication systems is proposed by using the chaotic property of the memristor. Phase portraits, Lyapunov exponential spectrum, and bifurcation diagrams of the memristor-based chaotic circuit were investigated. A Fuzzy-PID controller was used for master-slave synchronization of memristive chaotic circuit and in secure communication application, three images were also used for encryption and decryption. NI 6251 DAQ card was used to obtain real-time results. Information entropy values, correlation coefficients (CC), peak signal to noise ratio (PSNR), structural similarity index (SSIM), correlation coefficients for the horizontal, vertical and diagonal directions from the three encrypted images, number of pixels change rate (NPCR) and unified average changing intensity (UACI) are calculated to test encryption/decryption performance in the designed system. The results obtained from real-time applications and simulations prove that memristor-based chaotic circuits can be used in secure communication systems where privacy is important.

Machine Learning Techniques for True and Fake Job Posting

According to research, there are around 188 million unemployed people around the globe. We may find many job vacancies on job portals and across the internet to help the job seekers. India alone has more than a hundred job portals. One major issue people face here is that the job seekers are not sure if the employer is real or fake. Most of these portals do not have a system that could check if the employer posting a job is real or fake. Scammers are making use of this opportunity to post fake job offers which might look genuine to the job seekers applying for it. The poor job seekers might lose a large amount of money and time. A best possible solution for this problem would be that the job portal itself being able to identify if the job being posted is real or fake. Paper suggests using a machine learning model to achieve this goal. An idea here is to use natural language processing to understand and analyze the job posting and then making use of a machine learning model to predict if the job posting is real or fake. The first step is to import a dataset which has real life, real, and fake job posting. In this project, Employment Scam Aegean Dataset provided by University of Aegean Laboratory of Information and Communication system security is being used. Linear SVC is being used in this project for predicting real and fake job posting on a job portal.

Tunable asymmetric acoustic transmission device based on acoustic grating and sonic crystal with point defect

A numerical demonstration is given of the feasibility of a newly designed tunable asymmetric acoustic transmission device, for which the acoustic transmission coefficients for perpendicularly incident left- and right-running waves are different at a particular single frequency within a forbidden zone. The proposed device consists of a hybrid, sonic-crystal-based resonant structure with horizontal periodicity and a one-dimensional periodic rectangular acoustic grating with vertical periodicity. The former structure exhibits a wide bandgap through which only waves with particular combinations of their frequency and propagation direction can tunnel. The direction dependence of the acoustic transmission is based on the geometrical asymmetry of the placement of the grating, and on the narrowband correspondence between the diffraction angle of the grating and the allowed transmission direction through the sonic-crystal-based structure. Angular and spectral tuning are possible by changing the grating and/or the sonic crystal periodicity. The device has potential applications in underwater acoustics for asymmetric transmission systems and secure communication systems.

Adaptive nonsingular integral-type dynamic terminal sliding mode synchronizer for disturbed nonlinear systems and its application to secure communication systems

This study proposes an adaptive nonsingular integral dynamic terminal sliding mode tracker/synchronizer for disturbed nonlinear systems along with its usage in safe communication systems. The convergence of the closed-loop structure under unknown uncertainty and disturbances is guaranteed via Lyapunov analysis. Furthermore, a parameter-tuning method is planned to approximate the upper bound of uncertainty and disturbance terms, since this latter is typically unknown in practice. The proposed approach is used to design a digital secure transmission scheme according to the chaotic systems. The effectiveness of the suggested approach is validated using computer simulations on a benchmark example of chaotic system. The obtained outcomes clearly confirm the ability of the planned control approach enables to attain the desired tracking/synchronizing performance despite the disturbances. Additionally, when implemented to the data encryption of a communication system, the proposed control and secure communication techniques enabled the complete and secure retrieval of the original digital sequences.

Complex Modified Projective Difference Function Synchronization of Coupled Complex Chaotic Systems for Secure Communication in WSNs

Complex-variable chaotic systems (CVCSs) have numerous advantages over real-variable chaotic systems in chaos communication due to their increased unpredictability, confidentiality, and the ease of implementation. Synchronization between the master and slave systems in CVCSs is key to achieving encryption and decryption. However, existing synchronization schemes for CVCSs require the amplitude of the chaotic signal to be much larger than that of the plaintext. Moreover, traditional chaotic masking of complete synchronization (CS) requires uniformity between the transmitter and receiver ends. Therefore, we propose a complex modified projective difference function synchronization (CMPDFS) of CVCSs to address these issues, where the modified projective matrix helps address the issues with the amplitude. The receiver end is reconstructed without uniformity of the transmitter. We design the CMPDFS controller and propose a new secure communication scheme for wireless sensor networks (WSNs). The basic principle is fundamentally different from traditional chaotic masking. Simulation results and security analysis demonstrate that the CMPDFS communication scheme has a large key space, high sensitivity to encryption keys, high security, and an acceptable encryption speed. Hence, the proposed scheme can improve the security of WSNs. Moreover, it also can be applied to similar communication systems.

PROPERTIES OF GENERATORS OF PSEUDO-RANDOM SEQUENCES CONSTRUCTED USING FUZZY LOGIC AND TWO-DIMENSIONAL CHAOTIC SYSTEMS

Context. The problem of generating pseudo-random sequences of bits using the rules of fuzzy logic and two-dimensional chaotic systems is considered.&#x0D; Objective. Pseudo-random sequences generators built using two-dimensional chaotic systems and fuzzy logic. The purpose of the work is to develop and implement pseudo-random bit sequences generators based on the rules of fuzzy logic and two-dimensional chaotic systems and to evaluate the statistical characteristics of the generated sequences using statistical tests of National Institute of Standards and Technology.&#x0D; Method. A method for generating pseudo-random bit sequences is proposed, which allows form bit sequences with characteristics that meet the requirements of secure communication systems and cryptographic protection of information based on the rules of fuzzy logic and two-dimensional chaotic systems. In the process of studying the operation of generators, histograms of the distribution of output values were constructed, which allows to clearly determine whether the entire range of output values of the twodimensional system could be used to generate pseudo-random bit sequence or only part of it. A study of the statistical characteristics of the generated sequences using a set of statistical tests was also performed.&#x0D; Results. Bit sequences formed using fuzzy logic rules and two-dimensional chaotic systems can be used to transmit information in secure communication systems.&#x0D; Results. The proposed generators were implemented in software, histogram analysis and evaluation of compliance with the criteria for a set of statistical tests of National Institute of Standards and Technology.&#x0D; Conclusions. The experiments confirmed the ability of the proposed generators to generate bit sequences with good statistical characteristics, which allows them to be recommended for use in practice in solving problems of cryptographic protection of information and secure transmission of information over open communication channels. Prospects for further research may be to create cryptographic methods of information protection based on the proposed pseudo-random bit sequences generators, the implementation of secure communication systems.

Physical Layer Security of Two-Way Ambient Backscatter Communication Systems

Achieving high network traffic demand in limited spectrum resources is a technical challenge for the beyond 5G and 6G communication systems. To this end, ambient backscatter communication (AmBC) is proposed for Internet-of-Things (IoT), because the backscatter device (BD) can realize communication without occupying extra spectrum resources. Moreover, the spectral efficiency can be further improved by using two-way (TW) communication. However, secure communication is a great challenge for accessing massive IoT devices due to the broadcasting nature of wireless propagation environments. In light of this fact, this article proposed a two-way ambient backscatter communication (TW-AmBC) network with an eavesdropper. Specifically, the physical layer security (PLS) is studied through deriving the analytical/asymptotic expressions of the outage probability (OP) and intercept probability (IP). Moreover, the outage probabilities (OPs) in high signal-to-noise ratio (SNR) regions are studied for the asymptotic behavior and the intercept probabilities (IPs) in high main-to-eavesdropping ratio (MER) regions as well. Through analysis and evaluation of simulation performance, the results show that (i) when considering the target node, the OP of the BD decreases with increasing SNR, that is, enhancing the reliability; (ii) an optimal value of BD’s reflection coefficient that maximize the reliability of backscatter link can be obtained; (iii) in high SNR regions, the OPs approach a constant; thus, the diversity orders are zero; (iv) when increasing the MER, the IP of target node decreases, suggesting the security enhances; (v) a trade-off exists between reliability and security which can be optimized by carefully designing the parameters.