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As a potential solution to improve wireless security, specific emitter identification is a lightweight access authentication technology. However, the existed deep learning‐based specific emitter identification methods are highly dependent on the training sample size, leading to serious overfitting problem when the training samples are inadequate, which obstructs their practical applications. To address this issue, an innovative data augmentation method to effectively expand the sample size is proposed. In this design, after data preprocessing, a random integration based data augmentation is applied to integrate several initial samples and generate new samples. Furthermore, compared with the existed methods, chaotic sequences are utilized to randomly set the integration weight of each initial sample, and thus enhancing the diversity of augmented samples. The superiority of the proposed chaotic integration‐based data augmentation method in accuracy, generalization ability and robustness is validated by the hardware implementation on digital mobile radio portable radios. [ABSTRACT FROM AUTHOR]

In recent years, key generation schemes based on the reciprocity of wireless channels have gained widespread attention in the field of wireless physical layer security. However, due to the openness of wireless channels, eavesdroppers may obtain partial legitimate keys by eavesdropping on the wireless channel. To address this issue, this paper proposes a wireless channel coding scheme that induces an "avalanche" of errors for eavesdroppers, which could maximize eavesdropper's bit error rate. The design of this scheme is based on the significant differences between the eavesdropping channel and the legitimate channel, and the average bit key disagreement ratio of the keys generated by the legitimate channel is around 8%. The scheme selects polar codes with strong error correction capabilities and chooses a coding rate matching the error level of the legitimate channel, forcing the eavesdropping channel's error rate into an "avalanche" state, where the error rate approaches 50%. This paper presents the structure of the encoder and determines the coding rate through simulation. Simulation results demonstrate that this scheme can significantly degrade the error rate of the eavesdropping channel while ensuring the prevention of eavesdroppers from obtaining secret information transmitted through the legitimate channel. [ABSTRACT FROM AUTHOR]

As automobile intelligence continues to develop, the electronic control units connected to the Controller Area Network (CAN) bus within vehicles face an increasing number of threats from potential attacks originating from the internet. To address this issue, an intrusion detection and defence method is proposed that is capable of detecting illegal messages through the use of frequency anomaly detection, and subsequently disrupting them through utilization of the CAN bus arbitration mechanism. This proposed method offers a simple implementation compared to traditional approaches, while being able to identify suspicious units and neutralize threats in real‐time. Experimental results demonstrate the effectiveness of this approach. [ABSTRACT FROM AUTHOR]

This Letter investigates the impacts of hardware impairments (HIs) and channel estimation errors (CEEs) on the secrecy performance of satellite communication networks with one legitimate user and one eavesdropper. Particularly, the authors derive the closed‐form expression for the secrecy outage probability (SOP) of the considered secrecy satellite communication networks. Besides, in order to research the impact of the HIs and CEEs at high signal‐to‐noise ratios, they obtain the asymptotic expression for the SOP, which gives efficient and fast method to evaluate the effect of the considered system parameters on the secrecy system performance. At last, Monte Carlo computer results are given to verify the effects of HIs and CEEs on the secrecy system performance. [ABSTRACT FROM AUTHOR]

Several gaps and errors in Fang et al. (2015) are identified. Their corrections as well as new results are reported. After these corrections, the successive convex approximation algorithm in Fang et al. (2015) is shown to generate an increasing, converging sequence of secrecy rates, which, for a degraded channel, converges to its secrecy capacity. The failure of the popular convex solver CVX to maximise secrecy rate is illustrated. Alternative algorithms are pointed out. [ABSTRACT FROM AUTHOR]

A closed-form expression of the achievable secrecy rate is derived in this study, which is used as the objective function to find the optimal time allocation of channel estimation and transmission. Theory analysis and numerical results demonstrate that the maximum secrecy capacity depends on the total time budget as well as the power at the transmitter. [ABSTRACT FROM AUTHOR]

A chaos shift parameter synchronisation (CSPS) system based on two different mutually coupled lasers synchronising with another laser is studied while a novel chaos shift orbit (CSO) encoding technique is presented for secret communication. CSPS between the emitter and receiver can still be obtained by shifting the emitter's parameter in real time, where the emitter operates its chaos to vary its orbit or jump across its orbit by using real‐time current changes of one laser. Then, a CSO encoding scheme is implemented successfully. The emitter has numerous real‐time shifting secret keys, so it is highly secure, and the signal is difficult to decipher. [ABSTRACT FROM AUTHOR]

The importance of encryption in free‐space optical communication systems has been increasing due to their widespread use. Herein, for the first time, the authors propose a novel two‐dimensional encryption system for free‐space optical communication using two spatial patterns as encryption keys. A data stream is physically encrypted with optical signals to reduce the risk of unauthorised third‐party intrusion into communication. The encryption and restoration of a binary data stream using the proposed encryption system are confirmed by simulation results. The authors believe that, in the future, the proposed system could be used as an encryption method at the physical layer level to achieve the desired level of safety determined by the user. [ABSTRACT FROM AUTHOR]

The double shadowed Rician model was recently proposed to describe some realistic physical signal propagation phenomena, where a Rician faded signal is impacted by cascaded shadowing processes. In this Letter, the authors study the outage performance of the double shadowed Rician model. More specifically, they investigate the impact of two different shadowing processes on the secrecy performance by deriving novel and exact expressions for secrecy outage performance metrics. The obtained results reveal the following physical implications: (i) when a Rician faded signal undergoes line‐of‐sight shadowing, which is further cascaded by another round of composite shadowing, the latter form of shadowing imposes larger impact on the secrecy performance; (ii) the widely investigated concept of 'protected zone' to improve the secrecy performance should not be limited to the legitimate transmitter but also extended to the legitimate receiver due to the adverse shadowing effect caused by objects in its vicinity; and (iii) the rate of outage performance degradation grows larger as the shadowings become severe. [ABSTRACT FROM AUTHOR]

Digital signal processing (DSP) cores (kernels) are key components of modern consumer electronics devices. However, protection of DSP kernels is very crucial considering its vulnerability to hardware threats such as reverse engineering (RE). Functional obfuscation is one of the security mechanisms which provide protection against RE. However, functional obfuscation logic is in itself vulnerable to removal attack. This Letter presents a novel anti‐removal logic (ARL) unit which ensures protection against the removal attack on functional obfuscation logic. Further, the ARL unit is itself safeguarded against removal attack by incorporating design architecture customisation and camouflaging. Designer can customise and camouflage the internal gate structure network of the ARL blocks post‐synthesis (post‐mapping and fitting). The proposed ARL unit integrated with functionally obfuscated DSP design, yielded lightweight and highly secured solution against removal attack when compared to an existing approach. The proposed approach reported on an average 42.57% reduction in gate count and on an average 66.67% enhancement in security compared to a recent existing approach. [ABSTRACT FROM AUTHOR]

The authors investigate the secure communication in multigroup multicasting cell‐free massive MIMO systems in the presence of an active pilot spoofing attack. With the imperfect estimated local channels at access points, a distributed conjugate beamforming with normalised power constraint policy is exploited for downlink multicasting transmission. Closed‐form expressions for the per‐user achievable rate and information leakage to eavesdropper are derived, respectively. Numerical results are presented to verify the correctness of their analytical results and quantitatively analyse the impacts of eavesdropper's spoofing pilot power and a number of groups on the secrecy performance of the considered systems. [ABSTRACT FROM AUTHOR]

In this Letter, the authors derive the closed‐form formulas for the generalised moment generating function of the Fisher–Snedecor F (F–S F) distribution, which enable us to effectively evaluate the probability of successful secure transmission over F–S F composite fading channels. Extensive numerical results are presented to validate the accuracy of their analytical framework. [ABSTRACT FROM AUTHOR]

A secret key can be generated between two legitimate parties from observations of the common wireless channel. However, key disagreement usually occurs due to the estimation errors. Considering a guard band, the key disagreement rate (KDR) is firstly derived in a closed‐form expression. Although increasing the size of the guard band can decrease KDR; the length of the raw key bit sequence is also shortened. To evaluate such an effect, the raw key generation rate is defined and derived. The simulation results verify the theoretical analysis and are useful for the determination of pilot power and guard band size. [ABSTRACT FROM AUTHOR]

Media‐based modulation (MBM) concept is exploited to increase physical layer (PHY) security in the presence of an illegitimate listener. A precoding design is developed to increase the mutual secrecy rate of MBM, and the secrecy mutual information expressions are derived. The provided analyses and numerical results have also shown that MBM is a perfect candidate for PHY security by providing the maximum achievable secrecy mutual information, even in the presence of channel estimation errors. [ABSTRACT FROM AUTHOR]

Physical layer security is a promising approach to establish secure communications based on the characteristics of wireless channels. A spatial signature based secure multiple‐input single‐output (MISO) orthogonal frequency division multiplexing (OFDM) system is proposed to disrupt the reception of a passive eavesdropper by holding two practically relevant assumptions: a limited feedback link for legitimate node and the unavailability of channel state information of eavesdropper. The proposed algorithm achieves a higher average secrecy rate than the conventional secure MISO‐OFDM systems in presence of a limited feedback link. [ABSTRACT FROM AUTHOR]

In passive keyless entry and start (PKES) systems, the car unlocks or starts the car when the key is in the proximity of the car. In conventional PKES systems, the car determines the physical proximity of the key on the basis of the received signal strength or the round‐trip time (RTT). However, the conventional schemes are vulnerable to relay attacks because the relay amplifies the signal and minimises the processing time. A solution to avoid the relay attacks in PKES systems is proposed, where the car verifies the proximity of the key on the basis of the correlation of the channel state information as well as the RTT. [ABSTRACT FROM AUTHOR]

In multi‐untrusted relay networks, the transmission should be carefully devised to guarantee both security and performance. A novel scheme with symbol separation and beamforming is proposed to improve secure transmission. First, the best two relays with the strongest channel gains are selected to deliver the separated real and imaginary parts of the confidential symbols. Then, directional beamforming is carefully designed to maximise the receptions of the real and imaginary parts at the two selected relays and to zero force the receptions at the other relays. The proposed scheme ensures a perfect physical layer security with high BER at untrusted relays, and an improved BER performance at the destination. Numerical simulations show the correctness and efficiency of the proposed scheme. [ABSTRACT FROM AUTHOR]

Recently, the authors proposed a physical‐layer key generation scheme for optical orthogonal frequency division multiplexing (OFDM) techniques in an indoor scenario. The key generation protocol exploits bipolar and real‐valued optical OFDM samples to create confidential keys. It determines a chunk of cyclic prefix samples positioned in the space of small channel impact to generate the confidential keys during the session duration. This key‐generation approach offers strong computational security to counter passive eavesdroppers and key creation on the fly, with zero bit‐mismatch rates. In this Letter, the authors evaluate the randomness of the confidential keys produced from the recently proposed key‐generation protocol to validate if the keys are truly random. The authors apply a statistical test suite of the National Institute of Standards and Technology to test randomness. The results demonstrate that the keys generated from the proposed key generation system pass all the tests. The results also demonstrate that the proposed key generation system provides uncorrelated keys with an approximately equal probability of bits (discrete uniform distribution) on an average, which yields a high security system against statistical attacks. [ABSTRACT FROM AUTHOR]

In device‐to‐device (D2D) underlaying cellular networks, interference generated by D2D communications can be exploited to improve secrecy rate of cellular users (CUE). The security‐oriented distributed access selection algorithm is proposed, in which each D2D pair decides whether to access to radio resources according to its local channel state information without considering the locations of D2D pairs and Eve. The ergodic secrecy rate of CUE and the data rate of D2D pairs in the proposed scheme are investigated. Simulation results show that the proposed scheme can achieve an impressive secrecy performance gain. [ABSTRACT FROM AUTHOR]

Recently, many works have focused on analysing the metrics of physical layer security over different wireless channels such as additive white Gaussian noise, Rayleigh, Rician and Nakagami‐m fading distributions. To extend the analysis to the general case, the α–μ fading channel is considered, which can span the aforementioned cases. For this purpose, the physical layer security over the α–μ fading channel is presented. The closed‐form expressions for the probability of positive secrecy capacity and upper bound of the secrecy outage probability are derived. Their accuracies are assessed through comparison of theoretical analysis and simulations results. [ABSTRACT FROM AUTHOR]

The distributed localisation with M‐ary quantised data at sensor nodes is investigated in the presence of Byzantines from the attacker's perspective. The Byzantine nodes attack the network by transmitting falsified data to the fusion centre (FC) to deteriorate the performance of the distributed target localisation, where the independent and probabilistic Byzantine attack model is considered. By making the determinant of Fisher information matrix be zero, the optimal Byzantine attack strategy, which makes the FC incapable of estimating target location using the data at sensor nodes, is found. Numerical results show that the security performance of the distributed localisation improves sharply as the number of quantisation bits increases. Moreover, the security performance also increases tremendously as the attack probability decreases. Hence, the Byzantine attacker faces a trade‐off between the performance damage and the hazard to be identified. [ABSTRACT FROM AUTHOR]

A system that achieves compression using artificial DNA packaging with the support of two algebraic curves is presented, whereby the Hermitian channel code algorithm introduces gain and safety. Additionally, performance results are presented with a gain of 7 dB against uncoded quadrature phase shift keying and 1 dB against McEliece, for a bit error rate of 10−3. The results of the security levels compared with the McEliece system are also presented. [ABSTRACT FROM AUTHOR]

An interleave‐division multiple‐access (IDMA) system supports the presence of multiple users in a cell by resorting to a different interleaver per user. Therefore the choice of the interleaver critically impinges on system performance. A new interleaver structure is proposed for the so‐called STBC–OFDM–IDMA [space‐time block coding (STBC), orthogonal frequency division multiplexing (OFDM) and IDMA] architecture, combining the viable features of the STBC, the OFDM and the IDMA techniques. This interleaver is based on the new idea of adopting permutation control keys generated using two cryptography elliptic curves in which the degree of randomness of the interleaved sequence is scalable by using several rounds and a different subkey in each round. In addition to offering a certain degree of data security, it is shows through simulation results that the resulting architecture incorporating the proposed interleaver yields a viable bit error rate performance. [ABSTRACT FROM AUTHOR]

A novel chaos‐based selected mapping (SLM) scheme is proposed for physical layer security in OFDM‐PONs, where a Hénon chaos map is employed to create a large key space for OFDM data encryption. The transmission performance is significantly improved due to the peak‐to‐average power ratio reduction in the SLM scheme. High quality 8.9 Gbit/s 16‐QAM OFDM encrypted data transmission is demonstrated over a 20 km single‐mode fibre. [ABSTRACT FROM AUTHOR]

In this reported work, the frequency diverse array concept is employed to construct an orthogonal frequency‐division multiplexing (OFDM) transmitter that has the capability of securing wireless communication in free space directly in the physical‐layer without the need for mathematical encryption. The characteristics of the proposed scheme in terms of its secrecy performance are validated via bit error rate simulation under both high and low signal to noise ratio scenarios using the IEEE 802.11 OFDM physical‐layer specification. [ABSTRACT FROM AUTHOR]

A wireless physical layer network coding (WPLNC) technique in a decentralised and distributed relay network where a maliciously behaving relay may be present is studied. Most research has optimistically assumed altruistic cooperation of relays. The malicious node can lead to a significant disorder among the other relays by selecting its own WPLNC mapping. This scenario is described as a static (single‐shot) incomplete information game where a node type – either friendly or malicious – of the relay is its private information. The focus is on the existence of particular equilibria given the probability of the presence of a malicious node. [ABSTRACT FROM AUTHOR]

Pilot power allocation is investigated under the framework of physical layer secure communications in time‐division duplex systems, where the secret keys are generated from the estimates of sparse wireless channels. The joint optimisation of secret key capacity and sparse channel estimation performance based on pilot power allocation is formulated as a convex optimisation problem. Considering the fairness between these two sides, a scaling factor is introduced. Then, a scheme is proposed to fast solve the problem by looking up a table and using existing optimisation solvers. Simulation results show that a proper scaling factor can make a trade‐off between the secret key capacity and sparse channel estimation performance. [ABSTRACT FROM AUTHOR]

A covert communication system using a random carrier having skewed α‐stable distribution is introduced. The proposed method utilises the random signals with skewed α‐stable distributions exhibiting antipodal characteristics to encode the binary information at the transmitter. The receiver recovers these positive and negative skewed α‐stable distributed random signals by switching at different time instants, where only the receiver has the correct switching order. The third‐order statistic, given as sample skewness, is used to determine the message inside the receiver structure. The main purpose of constructing such a communication system is to improve the security aspect by avoiding the self‐repeating autocorrelation behaviour of the transmitted signal in the time domain. The improvement of security is shown by comparing the fractional lower‐order covariance with the reference study. According to the bit error rate results, the proposed method also shows better performance when the impulsiveness of the random carrier having skewed stable distribution is increased. [ABSTRACT FROM AUTHOR]

A new parental control method to prevent unauthorised usage of touch devices by kids is proposed. The impact of rapidly advancing technology on the developing child has seen an increase exposition to new forms of danger. Studies reveal that 97% of US children under the age of four use mobile devices. A reliable and efficient method to prevent the use of touch devices by preschool children is proposed. The proposed method is based on the analysis of the neuromotor characteristics of the users according to the decomposition of simple drag and drop tasks using the kinematic theory of rapid human movements. The experimentation is conducted on a publicly available database with samples obtained from 89 children between 3 and 6 years old and 30 adults. The results are compared with an existent system based only on task time and accuracy. Finally, both systems are combined at score level to achieve better performances. The results, with correct classification rates over 96% in the combined system, show the discriminative ability of the proposed neuromotor-inspired features and the possibility of combining this system with others to improve their final performance. [ABSTRACT FROM AUTHOR]

The joint effects of feedback delay, limited feedback and channel estimation errors on the secrecy performance of a multiple‐input–single‐output (MISO) system employing transmit beamforming against passive eavesdropping are investigated. Closed‐form expressions of the effective secrecy throughput which characterise the average rate of achieving reliable and secure transmissions are derived. Simulation results verify the theoretical analysis and show that different from feedback delay and limited feedback which degrade performance, imperfect channel estimation may not always harm the secrecy throughput. Furthermore, it is interesting to find that there exists an optimal transmit signal‐to‐noise ratio (SNR) for achieving the maximal secrecy throughput and channel state information imperfections will increase the optimal value of the transmit SNR. [ABSTRACT FROM AUTHOR]

The growing demand for anti‐eavesdropping security has inspired the study of physical‐layer security in wireless communications. Relay‐assisted secure backscatter communications are considered. The secrecy rate of the system is studied and the condition for a positive secrecy rate is analysed. The optimal relay selection algorithm and a suboptimal selection algorithm with much lower computational complexity are proposed. Simulation results show that the designed selection algorithms significantly outperform random selection in terms of average secrecy rate. The suboptimal selection approximately achieves the same average secrecy rate as the optimal selection. [ABSTRACT FROM AUTHOR]

In wireless sensor networks, the clustering routing protocol is commonly used for energy efficiency. However, routing protocols without proper security suffer from many security vulnerabilities. Hence, a key renewal scheme based on the clustering routing protocol is proposed. To apply the key renewal scheme with sensor authentication, sensor nodes are first authenticated during the key establishment procedure and then the symmetric key is updated periodically using hash functions. The simulation results show that the proposed key renewal scheme lengthens the network lifetime and has shorter activity time of attackers in spite of increasing the number of compromised nodes. [ABSTRACT FROM AUTHOR]

For simultaneous wireless information and power transfer (SWIPT), secure transmission is an important issue. The power allocation problem is investigated to maximise the achievable secrecy rate in a downlink orthogonal frequency division multiple access system with a power splitting SWIPT scheme. Unlike the traditional wireless communication systems, it is assumed that the legitimate receivers have no energy storage capability. The legitimate receivers harvest the energy from the received signals by using a power splitting scheme to meet the circuit‐power constraint for information decoding. The problem is formulated as a power allocation optimisation problem under the transmit power constraint and the energy harvesting constraint which is solvable. It is shown from simulations that the proposed optimal power allocation scheme outperforms the conventional uniform power allocation scheme. [ABSTRACT FROM AUTHOR]