Search Results (156)

As ocean resources are further developed and utilized, bionic covert underwater acoustic communication (CUAC) is increasingly important for military and underwater telemetry applications. The primary purpose of this study was to design a highly secure and undetectable text information (TI) encryption mechanism to realize CUAC using real bottlenose dolphin vocalizations (BDVs). For this purpose, a chaotic encryption scheme, spread spectrum (SS) technology, and a modified chaotic Hénon map (MCHM) were integrated into a TI encryption and hiding (EH) mechanism. Four BDVs and four test TIs were employed to demonstrate the performance of the proposed MCHM-based TI EH mechanism (MCHMTIEHM). The simulation results show that the MCHMTIEHM yields more accurate de-hiding and decryption results. When the correct encryption and decryption parameters were used, the test TI was completely recovered and could be recognized by humans. When the MCHM encryption and decryption parameters SP_x and n_I were not identical, tests involving TI01, TI02, TI03, and TI04 demonstrated correct de-hiding and error decryption performance; in particular, the test TI had superior correct de-hiding and error decryption results, was unrecoverable, and could not be recognized by the human eye. The modified amplitude correlation coefficient (ACC) and modified unified average amplitude change intensity (UACI) metrics were used to evaluate the hiding performance of MCHM-based encryption of TI using BDVs. The simulation results show that the average modified ACC and average UACI were 0.99995924 and 3.84 × 10⁻⁶, respectively. Performance was evaluated in terms of the average number of changing SS bit rates (NCSSBRs), the average number of changing bit rates (NCBRs), and the average number of changing character rates (NCCRs) for correct de-hiding and correct/erroneous TI decryption. The average NCSSBRs, NCBRs, and NCCRs were all 0% in correct de-hiding and encryption scenarios, while they were 49.29%, 47.65%, and 98.10%, respectively. with correct de-hiding and error-encryption scenarios. In summary, the proposed MCHMTIEHM yields superior encryption and hiding performance. Full article

In this work, we investigate covert communication with a cognitive jammer (CJ) embedded in a public communication system. Specifically, while the transmitter continuously transmits public messages to the receiver, it may also transmit its covert messages opportunistically, and a CJ is utilized to assist the covert communication. To evaluate the covert performance, we derive the detection error probability (DEP) for both the CJ and the warden, as well as the average covert rate (ACR). Our analysis indicates that applying a CJ to assist covert communication embedded in a public communication system can outperform the scheme with an uninformed jammer or without a jammer in terms of covertness. A high public transmission rate can degrade the covertness; however, improving the detection accuracy of the CJ can contribute to enhanced performance in terms of both covertness and ACR. Full article

This paper proposes a novel covert communication paradigm in which covertness emerges from network-induced structural uncertainty, eliminating the traditional reliance on pre-shared secret pilots in multi-user cooperative networks. Unlike conventional schemes that create information asymmetry through secret training sequences, we show that structural uncertainty naturally arises from user selection in spatially dispersed networks. Specifically, we consider a public pilot aided system under a worst-case adversarial assumption where Willie possesses full knowledge of all individual channel state information (CSI) but remains uncertain about the active subset of cooperative users. We prove that this selection-induced structural uncertainty renders different transmission states statistically indistinguishable from Willie’s perspective, thereby forcing the optimal detector to reduce to an energy-based test. The proposed framework demonstrates that robust covertness can be achieved without secrecy-based coordination, providing a scalable and practically viable alternative to secret pilot management in future wireless networks. Full article

Wi-Fi networks used in smart grids are essential for enabling communication between smart meters and data aggregation units. A key challenge, however, is the ability to hide the existence and traffic patterns of these communications, so that sensitive information exchanges cannot be easily detected or intercepted. Unfortunately, most existing solutions do not provide support for traffic prioritization and steganographic channel encryption. In this paper, we propose a novel covert channel with Quality of Service (QoS) and encryption support for smart grid environments based on the IEEE 802.11 standard. We introduce an original steganographic approach that leverages the backoff mechanism, the Enhanced Distributed Channel Access (EDCA) function, frame aggregation, and the StegoPaddingCipher algorithm. This design ensures QoS-aware traffic handling while enhancing security through encryption of the transmitted covert data. The proposed protocol was implemented and evaluated using the ns-3 simulator, where it achieved excellent performance results. The system maintained high efficiency even under heavily saturated network conditions with additional background traffic generated by other nodes. The proposed covert channel offers an innovative and secure method for transmitting substantial volumes of QoS-related data within smart grid environments. Full article

With the large-scale integration of distributed energy resources, modern energy systems are becoming increasingly dependent on communication networks for monitoring and control. This growing reliance exposes integrated energy systems (IESs) to potential cyber threats, as attackers may exploit vulnerabilities in communication protocols to disrupt system operation. However, most existing studies primarily investigate the stable operation of electro–thermal coupled systems from a defensive standpoint, while paying limited attention to the potential economic damage that could be induced from an attacker’s perspective. Motivated by this gap, this paper develops an optimal coordinated attack strategy targeting both energy storage units and load-side resources from the attacker’s viewpoint. First, an economic dispatch model for an electricity–heat–gas integrated energy system is established, and a fully distributed solution algorithm is proposed to obtain the optimal economic operating cost. Subsequently, by compromising energy storage and load units with relatively low security levels, a three-stage coordinated cyber-attack framework is designed for the IES. In the first two stages, covert data integrity attacks (DIAs) are launched to inject falsified power information into the system. In the third stage, a denial-of-service (DoS) attack is introduced to operate in synergy with the DIAs, forcing the system to converge to a feasible yet economically suboptimal operating point. The optimal initiation timing of the DoS attack is derived through theoretical analysis. Simulation results demonstrate that the proposed strategy can induce an economic loss of approximately 21.7% while maintaining system feasibility. By revealing these latent vulnerabilities from an attacker-oriented perspective, this study provides a theoretical basis for the development of proactive defense mechanisms, thereby enhancing the long-term economic and operational security of future integrated energy systems. Full article

Unmanned aerial vehicles (UAVs) are pivotal for 6G ubiquity, yet their open line-of-sight channels increase vulnerability to interception, posing new challenges for covert communication. This paper proposes a joint optimization scheme for multi-UAV relay-assisted covert communication system with the maximum channel capacity relay selection (MCRS) criterion. Distinct from conventional single-UAV approaches, this scheme uniquely couples UAV geometric positions with the time-varying characteristics of the wireless channels, exploiting spatial diversity from UAV relays to mitigate small-scale fading in dense urban environment, and jointly optimizes the transmit power and UAVs’ altitude. Specifically, we first designed an optimal relay selection strategy and derived analytical expressions for detection error and outage probabilities over altitude-dependent Nakagami-m fading channels. Furthermore, we maximized the effective covert rate by jointly optimizing the UAVs’ hovering altitude and adaptive transmit power of source and relays, subject to covert constraints. Extensive numerical results demonstrate a near-perfect match between the derived theoretical expressions and Monte Carlo simulations and validate the accuracy of our theoretical model. Compared against conventional single-UAV and multi-fixed-altitude UAV benchmark schemes, simulations demonstrate that the joint optimization scheme with relay selection proposed significantly enhances the covert performance of UAV-assisted communication systems. Full article

Background: Topical Corticosteroids (TCS) are potent therapeutic agents associated with severe local and systemic adverse effects if misused. In Jordan, the unauthorized supply of TCS for cosmetic purposes and the mismanagement of dermatological conditions remain significant public health concerns. This study utilized a repeated-measures simulated patient (SP) methodology to evaluate community pharmacists’ stewardship of TCS across a spectrum of clinical risks. Methods: A national cross-sectional study was conducted across 380 randomly selected community pharmacies in Jordan. Each pharmacy received four covert visits (N = 1520) corresponding to four distinct clinical scenarios representing different risk levels: cosmetic whitening, acne management, fungal infection, and pediatric diaper rash. The primary outcome was appropriate Practice, defined as the refusal to dispense unsafe medication or the provision of evidence-based alternatives. Results: Stewardship behavior varied significantly by clinical context (p < 0.001). Pharmacists demonstrated a hierarchy of safety, adhering to guidelines most strictly in the Pediatric scenario (82.1% appropriate refusal) but frequently abandoning safety standards in the Cosmetic scenario (30.0% appropriate refusal). Notably, 70.0% of pharmacists dispensed potent steroids for facial whitening, and 26.1% voluntarily offered to compound unauthorized steroid mixtures (Khaltat). In the acne scenario, 52.1% dispensed the contraindicated TCS, while only 37.9% appropriately switched the patient to an evidence-based alternative. In the fungal scenario, 60.0% failed to visually inspect the lesion, leading to a 40.0% rate of inappropriate TCS dispensing. Multivariable regression indicated that pharmacists working in chain pharmacies (aOR: 2.15, 95% CI: 1.68–2.75) and those holding advanced degrees (PharmD/MSc) (aOR > 1.38) were significantly more likely to practice appropriate TCS stewardship. High workload (>200 prescriptions/day) was a significant barrier to safety (aOR: 0.55). Conclusions: Community pharmacists in Jordan exhibited selective TCS stewardship, demonstrating high vigilance for pediatric safety, but widespread illegal practice regarding cosmetic misuse and differential diagnosis that may be unethical. The study results warrant the need for further urgent research to understand why these practices are occurring and how best to address them. Full article

Physical-layer covert communication is increasingly challenged by powerful detectors that exploit the fine-grained statistical structure of received signals. In realistic Radio Frequency (RF) front ends, signal-dependent impairments such as power amplifier (PA) nonlinearity and In-phase and Quadrature (I/Q) imbalance induce transmitter-specific, non-Gaussian emission statistics under which conventional Gaussian embedding rules cause detectable distribution drift. We propose ResDiff, a two-stage learn-then-embed framework that first trains a symbol-conditional diffusion prior to capture a hardware-consistent emission manifold, then embeds covert information through bounded, variance-adaptive residuals spread over a K-symbol block with coherent block decoding at the legitimate receiver. Simulations under a severe impairment profile in an Additive White Gaussian Noise (AWGN) channel show that ResDiff improves stealthiness while maintaining reliable covert recovery and that increasing K reduces detectability by lowering the per symbol embedding pressure. Overall, the results indicate that hardware-aware generative priors, combined with rate-controlled block embedding, provide a practical path to covert-in-cover-traffic communication under modern detection capabilities. Full article

Covert communication assisted by unmanned aerial vehicles (UAVs) can achieve a low detection probability in complex environments through auxiliary strategies, including dynamic trajectory planning and power management, etc. This paper proposes a dual-UAV scheme, where one UAV transmits covert information while the other one generates stochastic jamming to disrupt the eavesdropper and reduce the probability of detection. We propose a dual-mode jamming scheme which can efficiently enhance the average covert rate (ACR). A joint optimization of the dual UAVs’ flight speeds, accelerations, transmit power, and trajectories is conducted to achieve the maximum ACR. Given the high complexity and non-convexity, we develop a dedicated algorithm to solve it. To be specific, the optimization is decomposed into three sub-problems, and we transform them into tractable convex forms using successive convex approximation (SCA). Numerical results verify the efficacy of dual-mode jamming in boosting ACR and confirm the effectiveness of this algorithm in enhancing CC performance. Full article

Relational aggression (RA) is characterised by social manipulation and covert harm, often involving fluid and overlapping experiences of both perpetration and victimisation. We used latent profile analysis (LPA) to identify subgroups of young Australian adults based on their self-reported experiences of RA and explore whether these RA typologies are associated with broader aggressive traits and behaviours. We used a community sample of Australian adults aged 18–25 (N = 206, Mean age = 21.8, SD = 2.24, 77% female). Three distinct profiles emerged: predominantly victimised, combined victims–perpetrators (enmeshed), and the uninvolved. We observed strong indications that the experience of RA, even when predominantly as victimisation, was associated with increased odds of experiencing and perpetrating any aggression or violent behaviour compared to the uninvolved (OR = 5.17, [1.42–18.87] and OR = 3.21 [1.09–9.63] for the enmeshed and victimised classes, respectively, perpetrating any violent act). Conclusion: These results suggest the bidirectional nature of RA extends into young adulthood, and that distinct RA profiles exhibit differing patterns of broader aggressive behaviour. This study highlights that any approaches to further investigating or intervening with RA require consideration of the bidirectional nature of RA between perpetration and victimisation. Full article

Disinformation refers to false or misleading information created with the deliberate intention to deceive and cause individual or societal harm. It is typically distinguished from misinformation, which involves falsehoods shared without deceptive intent, and from malinformation, which uses accurate information in misleading or harmful ways. Terms often used interchangeably in public debate—such as fake news, propaganda, and conspiracy theories—describe related but distinct phenomena with differing aims and methods. The term derives from the Soviet concept of dezinformatsiya, originally associated with covert influence operations and strategic deception. Over time, however, its meaning has expanded to encompass a wide range of manipulative practices enacted by both state and non-state actors. Disinformation can take textual, visual, and multimodal forms, including fabricated images and AI-generated content such as deepfakes. Motivations vary and may include political influence, economic gain, ideological mobilisation, or efforts to stigmatise specific groups. Although these practices have long historical precedents, digital and platformised communication environments have amplified their scale, speed, and persuasive potential. This entry provides a narrative overview and conceptual synthesis structured around four dimensions: the history of disinformation, the supply and diffusion mechanisms, the psychological, social, and narrative drivers, and the interventions designed to mitigate its impact. Full article

This article addresses a critical security challenge in Internet of Things (IoT) systems, which are vulnerable to traffic detection attacks due to their reliance on shared wireless communication channels. We propose a novel cooperative covert transmission strategy to enhance the security of IoT communications against these attacks through the implementation of physical-layer security mechanisms. Inspired by zero-forcing precoding techniques, the proposed approach enables cooperation between different IoT devices in the system to increase the likelihood of adversaries making incorrect conclusions about the communication activity of the targeted IoT device. The proposed covert communication strategy complements traditional security measures, provides a scalable solution, and is suitable for resource-constrained IoT environments. The numerical results in this article demonstrate significant improvements in protecting communications against traffic detection attacks, which contributes to the overall security and privacy of IoT systems. Full article

Network covert channels embed secret data into legitimate traffic, but existing methods struggle to balance undetectability, robustness, and throughput. Application-independent channels at lower protocol layers are easily normalized or disrupted by network noise, while application-dependent streaming schemes rely on handcrafted traffic manipulations that fail to preserve the spatio-temporal dynamics of real encrypted flows and thus remain detectable by modern machine learning (ML)-based classifiers. Meanwhile, with the rapid adoption of HTTP/3, Quick UDP Internet Connections (QUIC) has become the dominant transport for streaming services, offering stable long-lived flows with rich spatio-temporal structure that create new opportunities for constructing resilient covert channels. In this paper, a QUIC streaming-based Covert Channel framework, QuicCC-SMD, is proposed that dynamically Shapes Multi-Dimensional traffic features to identify and exploit redundancy spaces for secret data embedding. QuicCC-SMD models the statistical and temporal dependencies of QUIC flows via Markov chain-based state representations and employs convex optimization to derive an optimal deformation matrix that maps source traffic to legitimate target distributions. Guided by this matrix, a packet-level modulation performs through packet padding, insertion, and delay operations under a periodic online optimization strategy. Evaluations on a real-world HTTP/3 over QUIC (HTTP/3-QUIC) dataset containing 18,000 samples across four video resolutions demonstrate that QuicCC-SMD achieves an average F1 score of 56% at a 1.5% embedding rate, improving detection resistance by at least 7% compared with three representative baselines. Full article

Image steganography is crucial for secure communication, enabling covert data embedding within cover images. While traditional methods such as LSB embedding are vulnerable to detection, deep learning techniques like GANs and autoencoders have improved performance, yet they still struggle with dynamic adaptation to diverse secret data types, limited training datasets, and resilience to distortions. To address these issues, we propose a flexible framework with adaptive multi-encoder–decoder pairs, extensive dataset training, and an optimized architecture with specialized components. Our model achieves significant improvements in Secret Recovery Accuracy (SRA), Stego-Image Quality (SSIM, PSNR), and robustness to noise, with SSIM of 0.99 and recovery accuracy over 98%. It also reduces the detection rate, with an AUC approaching 0.5 in steganalysis. These results set a new benchmark for secure image transmission and privacy-preserving communication. Full article

A covert communication scheme is designed for pinching antenna (PA)-enabled integrated sensing and communication (ISAC) systems. The base station (BS) emits sensing signals to detect the potential eavesdropper while opportunistically performing covert multicast transmissions. To enhance covertness, the inherent power uncertainty of the sensing signals is exploited to confuse eavesdroppers, thereby creating protective coverage for the legitimate transmission. For the considered systems, we design an alternating optimization framework to iteratively optimize the baseband, beamforming, and PA positionson the two waveguides, in which successive convex approximation and particle swarm optimization methods are introduced. Simulated results confirm that the proposed scheme achieves the highest covert communication rates with different numbers of multicast users compared to benchmark methods. Furthermore, increasing the transmit power and the number of PAs can further improve the covertness performance. Full article