Biblio

In this work, we consider the application of the nonstationary channel polarization theory on the wiretap channel model with non-stationary blocks. Particularly, we present a time-bit coding scheme which is a secure polar codes that constructed on the virtual bit blocks by using the non-stationary channel polarization theory. We have proven that this time-bit coding scheme achieves reliability, strong security and the secrecy capacity. Also, compared with regular secure polar coding methods, our scheme has a lower coding complexity for non-stationary channel blocks.

Internet of Things (IoT) is becoming an emerging paradigm to provide pervasive connectivity where “anything“ can be connected “anywhere” at “anytime” via massive deployment of physical objects like sensors, controllers, and actuators. However, the open nature of wireless communications and the energy constraint of the IoT devices impose strong security concerns. In this context, traditional cryptographic techniques may not be suitable in such a resource-constrained network. To address this problem, an effective security solution that ensures a trade-off between security effectiveness and energy efficiency is required. In this paper, we exploit cooperative transmission between sensor nodes in IoT for e-Health application, as a promising technique to enhance the physical layer security of wireless communications in terms of secrecy capacity while considering the resource-impoverished devices. Specifically, we propose a dynamic and cooperative virtual multiple-input and multiple-output (MIMO) configuration approach based on game theory to preserve the confidentiality of the transmitted messages with high energy savings. For this purpose, we model the physical layer security cooperation problem as a non-transferable coalition formation game. The set of cooperative devices form a virtual dynamically-configured MIMO network that is able to securely and efficiently transmit data to the destination. Simulation results show that the proposed game-based virtual MIMO configuration approach can improve the average secrecy capacity per device as well as the network lifetime compared to non-cooperative transmission.

Physical layer security has a paramount importance in tactical wireless networks. Traditional approaches may not fulfill all requirements, demanding additional sophisticated techniques. Thus, Combined Interference and Communications (CIC) emerges as a strategy against message interception in Cognitive Radio Military Networks (CRMN). Since CIC adopts an interference approach under specific CRMN requirements and characteristics, it saves great energy and reduces the receiver detection factor when compared to previous proposals in the literature. However, previous CIC analyses were conducted under vaguely realistic channel models. Thus, the focus of this paper is two-fold. Firstly, we identify more realistic channel models to achieve tactical network scenario channel parameters. Additionally, we use such parameters to evaluate CIC suitability to increase CRMN physical layer security. Numerical experiments and emulations illustrate potential impairments on previous work due to the adoption of unrealistic channel models, concluding that CIC technique remains as an upper limit to increase physical layer security in CRMN.

Unlike the traditional key-exchange based cryptography, physical layer security is built on information theory and aims to achieve unconditional security by exploiting the physical characteristics of wireless channels. With the growth of the number of wireless devices, physical layer security has been gradually emphasized by researchers. Various physical layer security protocols have been proposed for different communication scenarios. Since these protocols are based on information-theoretic security and the formalization work for information theory were not complete when these protocols were proposed, the security of these protocols lacked formal proofs. In this paper, we propose a formal definition for the secrecy capacity in non-degraded wiretap channel model and a formal proof for the secrecy capacity in binary symmetric channel with the help of SSReflect/Coq theorem prover.

The growing need for reliable communication over untrusted networks has caused a renewed interest in adversarial channel models, which often behave much differently than traditional stochastic channel models. Of particular practical use is the assumption of a causal or online adversary who is limited to causal knowledge of the transmitted codeword. In this work, we consider stochastic-adversarial mixed noise models. In the setup considered, a transmit node (Alice) attempts to communicate with a receive node (Bob) over a binary erasure channel (BEC) or binary symmetric channel (BSC) in the presence of an online adversary (Calvin) who can erase or flip up to a certain number of bits at the input of the channel. Calvin knows the encoding scheme and has strict causal access to Bob's reception through feedback snooping. For erasures, we provide a complete capacity characterization with and without transmitter feedback. For bit-flips, we provide converse and achievability bounds.

In this study, we investigate the performance of FSO communication systems under more realistic channel model considering atmospheric turbulence, pointing errors and channel estimation errors together. For this aim, we first derived the composite probability density function (PDF) of imperfect Málaga turbulence channel with pointing errors. Then using this PDF, we obtained bit-error-rate (BER) and ergodic channel capacity (ECC) expressions in closed forms. Additionally, we present the BER and ECC metrics of imperfect Gamma-Gamma and K turbulence channels with pointing errors as special cases of Málaga channel. We further verified our analytic results through Monte-Carlo simulations.

In practical wireless communication systems, the channel conditions of legitimate users can not always be better than those of eavesdroppers. This realistic fact brings the challenge for the design of secure transmission over wiretap channels which requires that the eavesdropping channel conditions should be worse than legitimate channels. In this paper, we present a robust chaos-based information masking polar coding scheme for enhancing reliability and security performances under realistic channel conditions for practical systems. In our design, we mask the original information, wherein the masking matrix is determined by chaotic sequences. Then the masked information is encoded by the secure polar coding scheme. After the channel polarization achieved by the polar coding, we could identify the bit-channels providing good transmission conditions for legitimate users and the bit-channels with bad conditions for eavesdroppers. Simulations are performed over the additive white Gaussian noise (AWGN) and slow flat-fading Rayleigh channels. The results demonstrate that compared with existing schemes, the proposed scheme can achieve better reliability and security even when the eavesdroppers have better channel conditions than legitimate users, hence the practicability is greatly enhanced.

Network security and data confidentiality of transmitted information are among the non-functional requirements of industrial wireless sensor networks (IWSNs) in addition to latency, reliability and energy efficiency requirements. Physical layer security techniques are promising solutions to assist cryptographic methods in the presence of an eavesdropper in IWSN setups. In this paper, we propose a physical layer security scheme, which is based on both insertion of an random error vector to forward error correction (FEC) codewords and transmission over decentralized relay nodes. Reed-Solomon and Golay codes are selected as FEC coding schemes and the security performance of the proposed model is evaluated with the aid of decoding error probability of an eavesdropper. The results show that security level is highly based on the location of the eavesdropper and secure communication can be achieved when some of channels between eavesdropper and relay nodes are significantly noisier.

In this paper, security of secret key extraction scheme is evaluated for private communication between legitimate wireless devices. Multiple adversaries that distribute around these legitimate wireless devices eavesdrop on the data transmitted between them, and deduce the secret key. Conditional min-entropy given the view of those adversaries is utilized as security evaluation metric in this paper. Besides, the wiretap channel model and hidden Markov model (HMM) are regarded as the channel model and a dynamic programming approach is used to approximate conditional min- entropy. Two algorithms are proposed to mathematically calculate the conditional min- entropy by combining the Viterbi algorithm with the Forward algorithm. Optimal method with multiple adversaries (OME) algorithm is proposed firstly, which has superior performance but exponential computation complexity. To reduce this complexity, suboptimal method with multiple adversaries (SOME) algorithm is proposed, using performance degradation for the computation complexity reduction. In addition to the theoretical analysis, simulation results further show that the OME algorithm indeed has superior performance as well as the SOME algorithm has more efficient computation.

This paper presents a new technique for providing the analysis and comparison of wiretap codes in the small blocklength regime over the binary erasure wiretap channel. A major result is the development of Monte Carlo strategies for quantifying a code's equivocation, which mirrors techniques used to analyze forward error correcting codes. For this paper, we limit our analysis to coset-based wiretap codes, and give preferred strategies for calculating and/or estimating the equivocation in order of preference. We also make several comparisons of different code families. Our results indicate that there are security advantages to using algebraic codes for applications that require small to medium blocklengths.