Legitimate Transmitter Research Articles

Joint Precoding Optimization for Secure SWIPT in UAV-Aided NOMA Networks

Combination of unmanned aerial vehicle (UAV) and non-orthogonal multiple access (NOMA) is deemed as an promising solution to achieving massive connectivity in future wireless networks. In this paper, a UAV-aided NOMA scheme is proposed to achieve simultaneous wireless information and power transfer (SWIPT) and guarantee the secure transmission for ground passive receivers (PRs), in which the nonlinear energy harvesting model is applied. Each time frame is divided into two phases. In the first phase, the received power at each PR is maximized to achieve rapid charging. In the second phase, SWIPT is performed via NOMA with the remaining energy at each PR, and artificial jamming is generated at UAV together with the NOMA information to guarantee the security. The throughput of PRs is maximized, with the highest received jamming power cancelled at each PR via successive interference cancellation (SIC). This disrupts the eavesdropping effectively by jamming without affecting the legitimate transmission. Due to the non-convexity of these two optimization problems, we first convert them to convex ones and then propose iterative algorithms to solve them. Simulation results are presented to show the effectiveness of the proposed scheme.

Robust and Secure Beamforming for Intelligent Reflecting Surface Aided mmWave MISO Systems

In this letter, we investigate the robust and secure beamforming (RSBF) in an intelligent reflecting surface (IRS) aided millimeter wave (mmWave) multiple input single output (MISO) system, where multiple single antenna eavesdroppers (Eves) are arbitrarily distributed nearby the legitimate receiver (Bob). Considering the channel state information (CSI) of cascaded wiretap channels is imperfectly known at the legitimate transmitter (Alice), the RSBF design problems to maximize the worst case of achievable secrecy rate (ASR) are formulated under the total transmission power and unit-modulus constraints. Since the problems are difficult to solve optimally due to their non-convexity and coupled variables, we substitute the wiretap channels by a weighted combination of discrete samples and propose a RSBF scheme based on alternating optimization and semidefinite relaxation (SDR) techniques, for both colluding and noncolluding eavesdropping scenarios. Simulation results show that the proposed RSBF scheme can effectively improve the ASR and also outperforms other benchmark schemes.

Covert Localization in Wireless Networks: Feasibility and Performance Analysis

In this paper, we propose covert localization to improve the security of wireless localization networks, which can prevent the legitimate transmission of localization signals between anchors and agent from being detected by the illegitimate warden. Specifically, we first establish a framework of covert localization and demonstrate its feasibility when the warden suffers noise uncertainty. Then, with two specific noise uncertainty distributions, we derive the fundamental limit of localization accuracy, i.e., covert squared position error bound (CSPEB), which is the achievable localization accuracy for the agent while ensuring covertness for the warden. Theoretical analysis of CSPEB demonstrates the impact of different factors on the localization accuracy. Besides, in an energy-constrained scenario, we formulate a power allocation problem to refine anchors' power to minimize the CSPEB for a given total power budget and develop an algorithm based on the semidefinite program (SDP). Simulation results verify our theoretical analysis by evaluating the effect of several representative factors on the CSPEB and show the superiority of the SDP-based power allocation algorithm to the other baseline methods.

عقل المسلم وقضايا العقيدة

العقل في اللغة يطلق على معان متعددة من أهمها: الحجر، الجمع، الحبس، التثبت في الأمور، التميز، الفهم، المسک، الملجأ . العقل اصطلاحا يطلق على أربعة معان: يطلق على الأداة الغريزية في الإنسان، وعلى العلوم التي يکتسبها الإنسان بتلک الأداة، وعلى العلوم الضرورية، وعلى العمل بمقتضى الشرع. الصحيح في مکان العقل أنه له تعلق بالقلب والدماغ معا. للعقل منزلته السامية والرفيعة في دين الإسلام بل هو إحدى الضرورات الخمس التي ما جاءت الشرائع إلا لتحصيلها وتکميلها. العقل مخلوق من مخلوقات الله تعالى له مدارکه المحدودة، ومجالاته المعلومة، وأنه في حاجة ماسة إلى الوحي ليهتدي به إلى کامل الصواب، وخاصة في قضايا الإيمان بالغيب. العقل في قضايا العقيدة غير ملغي تماما، کما أنه لا يعتمد عليه وحده في معرفة کل ما يتعلق بها بل يستعان بالعقل في فهم نصوص الشرع وأمور العقيدة، وهي بفضل الله تعالى ليس فيها ما يناقض العقول السليمة. لا يوجد أي تعارض بين القواطع النقلية الشرعية، والعقلية، وما قيل في ذلک إنما هو مجرد وهم والشريعة لا تأتي بما تحيله العقول، وإنما تأتي بما تحتار فيه العقول. لا توجد ديانة کرمت العقل، ورفعت من شأنه مثل دين الإسلام. وما أشيع أخيرا من أن تعاليم الإسلام لا تتماشى ومقتضى العقل إنما هي مجرد دعوى من مغرضين لا يسندها الواقع ولا العقل السليم. Abstract: The Mind in language are called Multiple meanings , Among the most important: Quarantine, Plural, Confinement, Verification in matters, distinction, understanding, grabbing, shelter. The Mind in terminology refers to four meanings: it is called the instinctive tool in man, the science that a person acquires with that tool, the necessary sciences, and the work according to Sharia. The correct place for the mind that it has attached to the heart and the brain together. The mind has its supreme and high standing in the religion of Islam, It is one of the five necessities that did not come Sharia except to collect them and supplement them. The mind is a creature of God Almighty who has limited awareness, and its known fields, and that it is in urgent need to revelation to guide him to the fullness of righteousness, especially in matters of faith in the unseen. The mind in matters of doctrine is completely canceled, It also does not depend on him alone in knowing everything related to it, but uses the mind to understand the provisions of Sharia and matters of doctrine, which, thanks to God Almighty, have nothing to contradict sound minds. There is no contradiction between the admissible legitimate transmission, and the mentality, and mental, and what was said about it is merely an illusion and the Sharia does not bring what minds refer, but rather what minds boggle. There is no religion that honored the mind, and raised from Its value is like the religion of Islam. And what is finally rumored That the teachings of Islam are inconsistent with the imperative of reason It is just a suit of disinterested, it is neither backed by reality nor by a sound mind. Key words: mind, Muslim, issues, doctrine.

IRS-Based Wireless Jamming Attacks: When Jammers Can Attack Without Power

This paper proposes to use Intelligent Reflecting Surface (IRS) as a green jammer to attack a legitimate communication without using any internal energy to generate jamming signals. In particular, the IRS is used to intelligently reflect the signals from the legitimate transmitter to the legitimate receiver (LR) to guarantee that the received signals from direct and reflecting links can be added destructively, which thus diminishes the Signal-to-Interference-plus-Noise Ratio (SINR) at the LR. To minimize the received signal power at the LR, we consider the joint optimization of magnitudes of reflection coefficients and discrete phase shifts at the IRS. Based on the block coordinate descent, semidefinite relaxation, and Gaussian randomization techniques, the solution can be obtained efficiently. Through simulation results, we show that by using the IRS-based jammer, we can reduce the signal power received at the LR by up to 99\%. Interestingly, the performance of the proposed IRS-based jammer is even better than that of the conventional active jamming attacks in some scenarios.

A Game-Theoretic and Experimental Analysis of Energy-Depleting Underwater Jamming Attacks

Security aspects in underwater wireless networks have not been widely investigated so far, despite the critical importance of the scenarios in which these networks can be employed. For example, an attack to a military underwater network for enemy targeting or identification can lead to serious consequences. Similarly, environmental monitoring applications such as tsunami prevention are also critical from a public safety point of view. In this work, we assess a scenario in which a malicious node tries to perform a jamming attack, degrading the communication quality of battery-powered underwater nodes. The legitimate transmitter may use packet level coding to increase the chances of correctly delivering packets. Because of the energy limitation of the nodes, the jammer's objective is twofold: disrupting the communication and reducing the lifetime of the victim by making it send more redundancy. We model the jammer and the transmitter as players in a multistage game, deriving the optimal strategies. We evaluate the performance in a model-based scenario and using real experimental data, performing a sensitivity analysis to evaluate the performance of the strategies if the real channel model is different from the one they use.

Learning an Adversary’s Actions for Secret Communication

Secure communication over a wiretap channel is investigated, in which an active adversary modifies the state of the channel and the legitimate transmitter has the opportunity to sense and learn the adversary's actions. The adversary has the ability to switch the channel state and observe the corresponding output at every channel use while the encoder has causal access to observations that depend on the adversary's actions. A joint learning/transmission scheme is developed in which the legitimate users learn and adapt to the adversary's actions. For some channel models, it is shown that the achievable rates, defined precisely for the problem, are arbitrarily close to those obtained with hindsight, had the transmitter known the actions ahead of time. This initial study suggests that there is much to exploit and gain in physical-layer security by learning the adversary, e.g., monitoring the environment.

Beyond Secrecy Rate in MISO Wiretap Channels: An Information Jamming Approach

Cooperative jamming is a widely used approach for improving the security of wireless networks. In this approach, a friendly jammer sends jamming signals to disrupt the reception of the eavesdropper, which inevitably interferes with the legitimate receiver. In this paper, we propose a novel approach, namely, information jamming, to exceed the secrecy rate achieved by the traditional cooperative jamming approach in a multiple-input single-output (MISO) wiretap channel. We propose that multiple multi-antenna information jammers (iJammers) transmit the source signals of the legitimate transmitter rather than independent noise signals for simultaneously enhancing the signal strength at the legitimate receiver and canceling the received signal at the eavesdropper. Specifically, we aim at maximizing the achievable secrecy rate by jointly optimizing the beamforming vectors at Alice and iJammers, subject to the individual transmit power constraints. We first propose a semi-definite relaxation based approach to solve the original non-convex problem optimally. For ease of implementation, we then provide a suboptimal distributed information beamforming scheme, whose optimal solution is obtained in closed-form. Finally, we extend our study to the imperfect channel state information case. Simulation results show that our proposed information jamming approach significantly outperforms the traditional cooperative jamming approach in terms of achievable secrecy rate.

Artificial-Noise-Aided Energy-Efficient Secure Beamforming for Multi-Eavesdroppers in Cognitive Radio Networks

In this article, we investigate optimal beamforming at a multiantenna primary base station (PBS) and a multiantenna cognitive base station (CBS) for energy-efficient (EE) secure downlink communication in cognitive radio networks with one single-antenna primary user (PU), one single-antenna cognitive user (CU), and multiple single-antenna eavesdropping nodes. An artificial noise transmission scheme is used by CBS to protect the data against the eavesdropping security attacks at the cost of extra power consumption. To improve the secrecy energy efficiency (SEE), we propose a SEE maximization (SEEM) scheme by exploiting the instantaneous channel state information (CSI) of the eavesdroppers under the secrecy rate (SR) constraints of the PBS-PU and CBS-CU channels, the quality-of-service requirement of the PU, and the transmit power constraint of the CBS. When the eavesdropping links’ instantaneous CSI are unknown at the legitimate transmitters (i.e., PBS and CBS), we propose another SEEM scheme based on the statistical CSI of the eavesdropping links. Since the formulated optimization problems with fractional objective functions are nonconvex and mathematically intractable, we first transform them into equivalent subtractive problems, and then, employ the difference of two-convex functions approximation method to arrive at approximate convex problems. In addition, new two-tier optimal BF algorithms are proposed. Finally, simulation results are presented to illustrate the effectiveness and performance gains of our proposed SEEM schemes over conventional SR-only maximization and EE-only maximization schemes.

A Multi-Domain Anti-Jamming Strategy Using Stackelberg Game in Wireless Relay Networks

In this paper, we study the influence of a smart jammer on the design of a three-node frequency hopping communication system using an amplify-and-forward relay. The jammer is smart that it senses the frequency and transmit powers used by the legitimate transmitters including the source node and the relay, and optimally adjusts the sensing time and the jamming power allocation to maximize the performance damage of the relay system. We jointly consider the time domain and the power domain to design a multi-domain anti-jamming strategy. To model the interaction between the legitimate transmitters and the jammer, we use Stackelberg game and let the legitimate transmitters act as the leader while the jammer act as the follower. Based on backward induction, a genetic algorithm based on exponential distribution algorithm is proposed to obtain the optimal frequency-hopping speed and the optimal transmit powers of the legitimate transmitters. Simulation results show that the proposed multi-domain strategy outperforms single-domain schemes and the multi-domain random scheme. Moreover, the optimal placement of the relay is also discussed through simulations.

Hybrid Cryptosystem Based on Pseudo Chaos of Novel Fractional Order Map and Elliptic Curves

Securing transmission of information between legitimate transmitter and receiver sides is a great challenge for mathematicians, computer scientists and engineers in recent years. This paper aims at achieving three goals. The first of them is to introduce a novel fractional order two dimensional (2D) map having very complex chaotic behavior and distinct large positive values of Lyapunov exponents over wide range of parameters, compared with other 2D maps in literature. Secondly, a new reliable secure encryption scheme combining the associated chaotic pseudo-orbits of the proposed map with the advantages of elliptic curves in public key cryptography is suggested, for first time, and applied to colored images. The hybrid scheme is capable to confirm reliable secret keys exchange in addition to highly obscure and hide transmitted information messages. Finally, a thorough mathematical analysis of security performance and evaluation of encryption scheme immunity against all possible attacks are carried out and proved its efficiency and robustness.

Wireless Surveillance With Interference Exploitation in Unauthorized Underlaid D2D Networks

Interference exploitation has been considered an effective method to improve secrecy in underlaid device-to-device (D2D) communication networks. This paper studied interference exploitation in unauthorized underlaid D2D communication networks, where a cellular user (CU) transmits uplink information to a base station (BS) and a pair of suspicious D2D users (DUs) transmit the suspicious information at the same time. We used the beamforming of the full-duplex (FD) CU to simultaneously achieve the legitimate uplink transmission of the CU and wireless surveillance on the suspicious DUs. Considering the different priority levels of the tasks, we divided the real-time quality of service (QoS) requirements of the CU into three cases and formulated the problem in each case. We derived beamforming expressions for each problem in the perfect self-interference cancellation (PSIC) and then proposed targeted algorithms in the imperfect self-interference cancellation (ISIC). Finally, simulation results are provided to validate the effectiveness and the advantages of our proposed schemes in situations with different QoS requirements.

Physical Layer Key Generation Scheme Through Scrambling the Correlated Eavesdropping Channel

In this paper, we investigate the physical layer key generation scheme in most realistic scenarios where the correlation between the legitimate channel and the eavesdropping channel is considered. To degrade the correlation and improve the key generation capacity, a physical layer key generation scheme through scrambling the correlated eavesdropping channel is proposed. Firstly, the artificial noise is sent superimposed over pilots from the legitimate transmitter to confuse the eavesdropper. The artificial noise precoding matrix is randomly selected from decomposed unitary matrices orthogonal to the legitimate channel resulting in having no effect on legitimate channel. Then, the vector quantization algorithm and the winnow algorithm are respectively applied to quantize the channel characteristic and negotiate the generated random sequences to generate the final key. To further support the performance, we next present a power optimization scheme allocated to sending the artificial noise to maximize the generated key capacity under the total transmission power constraint. Finally, simulation results are presented to validate the effectiveness of our proposed scheme.

Passive and Active Wireless Device Secure Identification

Secure wireless device identification is necessary if we want to ensure that any transmitted data reach only a desired receiver. However the fact that wireless communications are by nature broadcast creates unique challenges such as identity theft, eavesdropping for data interception, jamming attacks to disrupt legitimate transmissions, etc. This paper proposes a new integrated radioprint framework (IRID) that has two main components. First, we propose a machine learning-based radio identification solution that relies on hardware variabilities of internal components of the transmitter caused during manufacturing, allowing us to achieve passive device identification. Second, we introduce a new kind of covert channel, based on variations in the emitted signal strength, which allows us to implement unique active device identification. We evaluate our proposed framework on an experimental test-bed of 20 identical WiFi devices. Although our experiments deal only with IEEE 802.11b, the approach can easily be extended to any wireless protocol. The experimental results show that our proposed solution can differentiate between network devices with accuracy in excess of 99% on the basis of a standard-compliant implementation.

Secure Symbol-Level Precoding in MU-MISO Wiretap Systems

Multi-user interference (MUI) is usually considered to be a harmful component in wireless communications. However, recently emerged symbol-level precoding techniques can constructively exploit the MUI by transforming it into useful signal at the receiver and contribute to symbol detection. This paper adopts this concept and aims to investigate the exploitation of the MUI to enhance both physical layer security against eavesdropping and the quality of legitimate transmissions. Particularly, we consider the problem of secure symbol-level precoding in multi-user multi-input single-output (MU-MISO) wiretap systems. Our goal is to design the symbol-level precoder to guarantee the quality of service (QoS) of all legitimate transmissions as well as ensure security against eavesdropping. The symbol-level precoder algorithms for physical layer security are developed under different assumptions about the availability of channel state information (CSI) of the legitimate and eavesdropping channels. Extensive simulation results validate the exploitation of MUI for security and illustrate the effectiveness of our proposed secure symbol-level precoding algorithms.

Low-Rate DoS Attacks Detection Based on MAF-ADM.

Low-rate denial of service (LDoS) attacks reduce the quality of network service by sending periodical packet bursts to the bottleneck routers. It is difficult to detect by counter-DoS mechanisms due to its stealthy and low average attack traffic behavior. In this paper, we propose an anomaly detection method based on adaptive fusion of multiple features (MAF-ADM) for LDoS attacks. This study is based on the fact that the time-frequency joint distribution of the legitimate transmission control protocol (TCP) traffic would be changed under LDoS attacks. Several statistical metrics of the time-frequency joint distribution are chosen to generate isolation trees, which can simultaneously reflect the anomalies in time domain and frequency domain. Then we calculate anomaly score by fusing the results of all isolation trees according to their ability to isolate samples containing LDoS attacks. Finally, the anomaly score is smoothed by weighted moving average algorithm to avoid errors caused by noise in the network. Experimental results of Network Simulator 2 (NS2), testbed, and public datasets (WIDE2018 and LBNL) demonstrate that this method does detect LDoS attacks effectively with lower false negative rate.

Secrecy Rate Analysis for Millimeter-Wave Lens Antenna Array Transmission

Physical layer security is vital to millimeter-wave communications enabled by large-scale arrays, particularly the energy-efficient lens antenna arrays (LAAs). However, the broad application of LAAs can be hindered by the lack of a proper understanding of the secrecy performance. This letter derives an asymptotic closed-form expression for the secrecy rate of LAA, despite the critical challenges including the coupling of unknown lens beam responses. With the new secrecy rate analysis, the optimal power assignment for the legitimate transmission is achieved, leading to the maximization of LAA secrecy. This power assignment is unprecedentedly studied in LAA due to the previous absence of an analytical secrecy rate. Simulations validate the accuracy of the analysis over wide ranges of system parameters.

An Intermittent Cooperative Jamming Strategy for Securing Energy-Constrained Networks

Friendly jamming is an unconventional approach to secure wireless communications. Specifically, a friendly jammer transmits jamming signals to an eavesdropper while a legitimate transmitter is sending data. The jamming signals only interfere with the eavesdropper, and thus, prevent data from being disclosed to unintended parties. Mainstream jamming schemes adopt a continuous jamming strategy (CJS), where the jammer is required to constantly transmit jamming signals in the entire duration of the legitimate transmission. In certain scenarios, however, the CJS may lead to excessive jamming, and cause a waste of energy and the degradation of jamming efficiency. To address the drawbacks of the CJS, we propose the concept of an intermittent jamming strategy (IJS), where a jammer alternates between jamming and non-jamming modes during the legitimate transmission. In this paper, we study the feasibility of the IJS for physical layer security. We first introduce a new metric to jointly measure security requirements and energy costs. Next, we formulate and solve an optimization problem with respect to the jamming duration proportion and the jamming power. Finally, we verify the feasibility of the IJS through extensive simulation experiments under different modulation methods.

Demonstrating and Mitigating the Risk of an FEC-Based Hardware Trojan in Wireless Networks

We discuss the threat that malicious circuitry (a.k.a. hardware Trojan) poses in wireless communications and propose a remedy for mitigating the risk. First, we present and theoretically analyze a stealthy hardware Trojan embedded in the forward error correction (FEC) block of an 802.11a/g transceiver. FEC seeks to shield the transmitted signal against noise and other imperfections. This capability, however, may be exploited by a hardware Trojan to establish a covert communication channel with a knowledgeable rogue receiver. At the same time, the unsuspecting legitimate receiver continues to correctly recover the original message, despite experiencing a slight reduction in signal-to-noise ratio (SNR) and, therefore, remains oblivious to the attack. Next, we implement this hardware Trojan on an experimental setup based on the Wireless Open Access Research Platform (WARP) and we demonstrate (i) attack robustness, i.e., the ability of the rogue receiver to correctly receive the leaked information and (ii) attack inconspicuousness, i.e., imperceptible impact on the legitimate transmission. Lastly, we theoretically analyze and experimentally evaluate a Trojan-agnostic detection mechanism, namely, channel noise profiling, which monitors the noise distribution to identify inconsistencies caused by hardware Trojans, regardless of their implementation details. The effectiveness of channel noise profiling is experimentally assessed using the proposed hardware Trojan under various channel conditions and a different covert Wi-Fi attack previously proposed in the literature.

Physical Layer Security Enhancement for Internet of Things in the Presence of Co-Channel Interference and Multiple Eavesdroppers

This paper investigates the secrecy performance of a multiuser system that utilizes transmit antenna selection scheme at the base station and adopts threshold-based selection diversity opportunistic scheduling over legitimate nodes. The legitimate transmission suffers from the presence of noncolluding (Non-Col) and colluding (Col) multiple passive eavesdroppers. Both the legitimate and eavesdropping nodes are assumed to suffer from co-channel interference (CCI) signals from independent channels that follow Rayleigh fading. Closed-form expressions for the probability density functions and cumulative density functions of the end-to-end signal-to-interference-plus-noise ratio for both eavesdropping scenarios in the presence of CCI signals are derived. In addition, closed-form expressions for the network secrecy outage probability (SOP) for Non-Col/Col scenarios are derived. At the high signal-to-noise ratio values, closed-form expressions for the asymptotic secrecy outage probabilities are obtained. Following this obtained asymptotic analysis, an optimization problem for power allocation is formulated and solved to improve the secrecy performance of the network by minimizing the asymptotic SOP for both Col and Non-Col cases. The derived analytical expressions are then validated using both simulations and numerical results.