Random binning is a widely used technique in information theory with diverse applications. In this paper, we focus on the output statistics of random binning (OSRB) using the Tsallis divergenceTα. We analyze all values of α ∈ (0,∞)∪{∞} and consider three scenarios: (i) the binned sequence is generated i.i.d., (ii) the sequence is randomly chosen from an ϵ-typical set, and (iii) the sequence originates from an ϵ-typical set and is passed through a non-memoryless virtual channel. Our proofs cover both achievability and converse results. To address the unbounded nature ofT∞, we extend the OSRB framework via Rényi’s divergence with order infinity, denotedD∞. As part of our exploration, we analyze a specific form of Rényi’s conditional entropy and its properties. Additionally, we demonstrate the application of this framework in deriving achievability results for the wiretap channel, where Tsallis divergence serves as a security measure. The secure rate we obtain through the OSRB analysis matches the secure capacity for α ∈ (0, 2] ∪ {∞} and serves as a potential candidate for the secure capacity when α ∈ (2,∞).

Estimating high-dimensional covariance matrices is crucial in various domains. This work considers a scenario where two collaborating agents access disjoint dimensions of $m$ samples from a high–dimensional random vector, and they can only communicate a limited number of bits to a central server, which wants to accurately approximate the covariance matrix. We analyze the fundamental trade–off between communication cost, number of samples, and estimation accuracy. We prove a lower bound on the error achievable by any estimator, highlighting the impact of dimensions, number of samples, and communication budget. Furthermore, we present an algorithm that achieves this lower bound up to a logarithmic factor, demonstrating its near-optimality in practical settings.

Random binning is a widely utilized tool in information theory, particularly for proving achievability bounds. In this paper, we investigate the output statistics of random binning (OSRB) for two cases: where the binned sequence is i.i.d. generated, and randomly chosen from an$\epsilon$-typical set using the Tsallis divergence$T_{\alpha}$measure for all values of$\alpha\in(0, \infty)$. For$\alpha=\infty$, due to the unbounded nature of$T_{\infty}$, we analyze the OSRB framework using Rényi's divergence criterion with the order of infinity, denoted as$D_{\infty}$. While exploring OSRB, we encounter a specific form of Renyi's conditional entropy and delve into its properties. Additionally, we demonstrate the effectiveness of this framework in establishing achievability results for wiretap channels, where Tsallis divergence serves as a security measure. The secure rate we obtain is equal to the capacity for$\alpha\in(0.2]$.

The increasing prominence of the Internet of Things (IoT) necessitates a thorough examination of IoT nodes, as they play a critical role in transmitting, processing, and storing private data. To address the security concerns associated with IoT nodes, researchers have proposed various methods for safeguarding sensitive information and ensuring secure communication. However, existing privacy protection approaches may not cater specifically to the IoT perception layer, rendering IoT devices vulnerable to security attacks. In response to this challenge, lightweight block ciphers, such as Shadow, have emerged as a potential solution. Shadow employs a novel combination technique of generalized Feistel structure and AND-RX operations, offering improved diffusion, stability, and resistance against attacks. In this article, we leverage integral cryptanalysis, particularly the mixed integral linear programming-aided method introduced by Xiang et al., to propose a 10-round integral distinguisher for Shadow-32. By extending this characteristic to 11 rounds with a novel approach, we propose the best integral distinguisher to date, featuring 16 balanced bits. In addition, we present a comprehensive integral attack on 14 rounds of Shadow-32, which exhibits a data complexity of 231, a time complexity of 256.429, and a memory complexity of 224 bytes. Although our proposed attack only targets 14 out of the 16 rounds of Shadow-32, it raises concerns about the practical security of the full-round Shadow-32. Consequently, further analysis is essential to ensure the security of IoT nodes, given their significance.

Dynamic index coding is a practical generalization of conventional index coding that deals with real dynamic traffic streams. We identify the code-constrained capacity region of a dynamic index coding problem with a complete bi-directional side information graph and introduce the performance metric of dynamic index coding gain to measure how dynamic index coding reduces the required data transmissions. A greedy dynamic index coding scheme is proposed that achieves the maximum coding gain almost everywhere in the identified capacity region. Although the greedy scheme attains the maximum coding gain, its selfish nature may unacceptably increase transmission delay. To address this issue, a time-shared friendly dynamic index coding scheme is introduced that achieves the maximum coding gain over the entire capacity region and offers a lower delay than its greedy counterpart. To obtain the minimum delay, a constrained optimization problem is formulated to tune time-sharing weights in the friendly scheme. The closed-form solution of the optimization is derived for the special two-flow case. Furthermore, the results and analysis are extended to dynamic index coding problems with arbitrary side information graphs. We also use analytical and simulation results to provide graphical intuition for the obtained results.

In this paper, we present a private voting system that consists of N voters who may vote to one of the K candidates or vote abstain. Each voter wants to compute the final tally, while staying private and robust against malicious voters, who try to gain information about the vote of the other voters beyond the final result, or send incorrect information to affect the final tally. We design an information-theoretic voting system that uses verifiable secret sharing and multi-party computation, which is secure and private as long as there are up to $\left\lfloor {\frac{{N - 1}}{3}} \right\rfloor $ malicious voters.

As data sharing has become one of the most popular services offered by cloud storage, designing public auditing mechanisms for integrity of shared data becomes more important. Two problems which arise in shared data auditing include preserving users identity and collusion resistant revocation of users. When data stored at the cloud is shared among a group of users, different users may modify and sign different data blocks which leaks signer identities to the public verifier. Also, when a user is revoked from the group, signatures generated by this user should be re-signed by the cloud server using re-signature keys. In addition, collusion of cloud server and the revoked user should leak no information about the private key of other users. In this paper, by employing a new proxy re-signature scheme, we propose a public shared data auditing mechanism that provides identity privacy and collusion resistant user revocation, simultaneously. The proposed protocol requires only lightweight computations at the user side for signing data blocks in real-time online phase. Moreover, our protocol supports large dynamic group of users, batch auditing and dynamic data operations. Experimental results demonstrate excellent efficiency of our scheme in comparison to the state of the art.

Nowadays, Smooth Projective Hash Functions (SPHFs) play an important role in constructing cryptographic tools such as secure Password-based Authenticated Key Exchange (PAKE) protocol in the standard model, oblivious transfer, and zero-knowledge proofs. Specifically, in this article, we focus on constructing PAKE protocol; that is, a kind of key exchange protocol which needs only a low entropy password to produce a cryptographically strong shared session key. In spite of relatively good progress of SPHFs in applications, it seems there has been little effort to build them upon quantum-resistant assumptions such as lattice-based cryptography and code-based cryptography to make them secure against quantum computer attacks. More precisely, there are two proposals based on lattice assumptions that utilize the SPHFs to construct PAKE secured in standard model. Considering quantum-resistant assumptions is less than straightforward and needs some relaxations. In this article, we introduce two new Approximate SPHF (ASPHFs) from error-correcting codes. Upon designing ASPHF, we can construct two efficient PAKE protocols. The security of our protocols could be proved based on the hardness of bounded decoding (BD) problem and learning with parity (LPN) problem in the standard model.

We study learning algorithms when there is a mismatch between the distributions of the training and test datasets of a learning algorithm. The effect of this mismatch on the generalization error and model misspecification are quantified. Moreover, we provide a connection between the generalization error and the rate-distortion theory, which allows one to utilize bounds from the rate-distortion theory to derive new bounds on the generalization error and vice versa. In particular, the rate-distortion-based bound strictly improves over the earlier bound by Xu and Raginsky even when there is no mismatch. We also discuss how “auxiliary loss functions” can be utilized to obtain upper bounds on the generalization error. A full version of this paper is accessible at [1].

In non-orthogonal multiple access (NOMA) systems, serving multiple users in shared resource blocks can allow untrusted users to overhear the messages of other users. In this context, we study a network consisting of a base station (BS), a near user and a far user, where the latter attempts to overhear the message of the former. The near user is a full-duplex (FD) node that can also act as a relay. Two operating scenarios are considered: 1) friendly jammer (FJ), where the FD node broadcasts noise for degrading the channel between the BS and the far user, while receiving data from the BS; and 2) friendly jammer relay (FJR), where, in addition to degrading the channel between the BS and the far user, the FD node relays the message of the far user. We investigate the secrecy performance of the network by characterizing the secrecy outage probability (SOP) in both scenarios. We obtain the exact SOP of the FJ case, and an approximation for the SOP of the FJR scenario, both expressed in closed-form. Numerical results confirm the accuracy of the analytical results. For a given BS power budget and power allocation to the users, it is demonstrated that the jamming and relaying powers are prominent factors to make the NOMA-FJR scheme superior to NOMA-FJ, as well as to conventional and cooperative NOMA schemes.

Code‐based digital signatures suffer from two main drawbacks: large public key size and slow signature generation. Large public key size is inherent in almost all the code‐based cryptosystems and other post‐quantum alternatives; however, slow signature generation is due to their specific structure. Most of the current code‐based signature schemes are constructed based on Courtois, Finiasz, and Sendrier (CFS) signature. CFS uses a counter to produce decodable syndromes or the complete decoding technique that imposes some extra computational cost to the signing algorithm for many choices of codes. In this study, the authors propose an efficient digital signature, PolarSig, which can reduce both public key size and signing time simultaneously. PolarSig uses some specific instances of polar codes that enable us to decode every random syndrome. Moreover, they apply puncturing and randomised omitting of frozen bits to protect the authors’ scheme from commonplace attacks targeting former cryptosystems based on polar codes. Besides, they prove that their signature is existentially unforgeable under a chosen message attack secure in the random oracle model.

Polar codes are novel and efficient error‐correcting codes with low encoding and decoding complexities. These codes have a channel‐dependent generator matrix, which is determined by the code dimension, code length and transmission channel parameters. A variant of the McEliece public‐key cryptosystem based on polar codes, called the PKC‐PC, is studied. Since the structure of the polar codes’ generator matrix depends on the parameters of the channel, the authors have used an efficient approach to conceal their generator matrix. The proposed approach is based on a random selection of rows of the matrix by which a random generator matrix is constructed. Using the characteristics of polar codes and introducing an efficient approach, they could reduce the public and secret key sizes, and computational complexity compared to the McEliece cryptosystem. Moreover, they show that PKC‐PC yields an increased security level against conventional attacks as well as possible vulnerabilities to the code‐based public‐key cryptosystems. Furthermore, they prove the security of the authors’ cryptosystem and show that its security is reduced to solve NP‐complete problems, called polar parameterised syndrome decoding and polar parameterised codeword existence.

In this paper, we consider the problem of data transmission for K-user interference channel (IC) with no channel state information (CSI) at transmitters. Each pair of transceivers with the aid of a particular precoder and a switching pattern structure tries to place its desired signal in a subspace which is linearly independent of interference signals. We show that if the channel values are known only to the receivers, the sum degrees-of-freedom (DoF) of the linear interference alignment (IA) with reconfigurable antenna at receivers is Kr/r2-r+K, where r = [√1+4K-1/2]. For previous methods when 3 ≤ K ≤ 104, the number of solvable problems to achieve maximum sum DoF is less than 2% of different cases while in our work there is not any limitation on the number of users. In comparison with the previous related works in our proposed method, there is no limit on the number of users and the reception modes. The result indicates that the maximum sum DoF for the K-user IC with asymptotically large values of K is √K/2. Thus, the sum DoF of such networks using the reconfigurable antenna at receivers grows sublinearly with the number of users, whereas it grows linearly in the case where transmitters have access to CSI.

In this paper, a new measure of correlation is introduced. This measure depends on a parameter α, and is defined in terms of vector-valued Lpnorms. The measure is within a constant of the exponential of α-Rényi mutual information, and reduces to the trace norm (total variation distance) for α = 1. We provide some properties and applications of this measure of correlation. In particular, we establish a bound on the secrecy exponent of the wiretap channel (under the total variation metric) in terms of the α-Rényi mutual information according to Csiszár's proposal.

The main security service in the connected world of cyber physical systems necessitates to authenticate a large number of nodes privately. In this paper, the private authentication problem is considered, that consists of a certificate authority, a verifier, many legitimate users (prover) and any arbitrary number of illegitimate users. Each legitimate user wants to be authenticated (using his personal key) by the verifier, while simultaneously wants to stay completely anonymous (even to the verifier and the CA). On the other hand, an illegitimate user must fail to authenticate himself. We analyze this problem from an information theoretical perspective. First, we propose a general interactive information-theoretic model for the problem. As a metric to measure the reliability, we consider the authentication key rate whose rate maximization has a trade-off with establishing privacy. Then, we analyze the problem in two different regimes: finite size regime (i.e., the variables are elements of a finite field) and asymptotic regime (i.e., the variables are considered to have large enough length). For both regimes, we propose schemes that satisfy the completeness, soundness and privacy properties. In finite size regime, the idea is to generate the authentication keys according to a secret sharing scheme. In asymptotic regime, we use a random binning based scheme which relies on the joint typicality to generate the authentication keys. Moreover, providing the converse proof, we show that our scheme achieves capacity in the asymptotic regime. For finite size regime our scheme achieves capacity for large field size.

An approach based on unitary transformation for the problem of estimating the number of signals is proposed in this study. Among the information theoretic criteria, the authors focus on the conventional Bayesian information criterion (BIC) in the presence of a uniform linear array. The sample covariance matrix of this array is transformed into the real symmetric one by using a unitary transformation. This real symmetric matrix has real eigenvalues and eigenvectors. Therefore its eigenvalue decomposition needs only real computations. Since the eigenvalues of this real symmetric matrix are equal to the eigenvalues of the sample covariance matrix, by replacing them in BIC formula, the term log‐likelihood of BIC does not change but it is obtained by fewer computations. Also by considering the resulting real eigenvectors instead of the complex eigenvectors as a part of free parameters in the parameter vector of the model, they have a reduction in the number of degrees of freedom in the penalty term of BIC. This reduction makes their proposed method outperform BIC. They refer to this approach as unitary BIC. A series of simulations are included to demonstrate the usefulness of this approach.

In this paper, we consider a binary erasure channel (BEC) with an unknown erasure probability of δ at a transmitter. In addition, we consider that δ has a constant value in each transmission block and the transmitter knows the probability distribution of δ. For this problem with the infinite block length, based on the distribution of the random variable δ, a multi-layer encoding strategy at the transmitter and a successive decoding strategy at the receiver are proposed. In our proposed scheme, based on the value of δ, the receiver can decode a part of transmitted data from different transmission layers. In order to have a comparison with other erasure correction codes, we generalize the result of the infinite block length to the finite block-length transmission. We show that considering the average transmission rate, our scheme has a better performance than the other erasure correction codes such as the Raptor and the MDS codes. We also analyze both the decoding complexity and bit error rate versus the erasure probability of the channel. Besides, by using a numerical comparison, we try to show that our proposed strategy outperforms other transmission strategies.

In this paper, we introduce a new measure of correlation for bipartite quantum states. This measure depends on a parameter$\alpha $, and is defined in terms of vector-valued$\textit {L}_{\textit {p}}$-norms. The measure is within a constant of the exponential of$\alpha $-Rényi mutual information, and reduces to the trace norm (total variation distance) for$\alpha =1$. We will prove some decoupling type theorems in terms of this measure of correlation, and present some applications in privacy amplification as well as in bounding the random coding exponents. In particular, we establish a bound on the secrecy exponent of the wiretap channel (under the total variation metric) in terms of the$\alpha $-Rényi mutual information according toCsiszár’s proposal.

Concurrent signatures allow two entities to generate two signatures in such a way that both signatures are ambiguous till some information is revealed by one of the parties. This kind of signature is useful in auction protocols and in a wide range of scenarios in which involving participants are mutually distrustful. In this study, to have quantum‐attack‐resistant concurrent signatures as recommended by National Institute of Standards and Technology (NISTIR 8105), the first concurrent signature scheme based on coding theory is proposed. Then, its security is proved under Goppa Parameterized Bounded Decoding and the Goppa Code Distinguishing assumptions in the random oracle model. In addition, performance evaluation shows that the proposal is approximately as efficient as Dallot scheme. The authors should highlight that their proposal can be a post‐quantum candidate for fair exchange of signatures without a trusted third party in an efficient way (without a high degree of interactions).

In this paper, we consider a secure network coding problem in which some secret keys are shared among legitimate nodes, and there exists an eavesdropper which is able to hear a subset of links. We show the equivalency of secure network coding under weak and strong secrecy conditions. For linear network coding, we show a stronger result: equivalency of "perfect secrecy and zero-error constraints" to "weak secrecy and $epsilon$-error constraints". This is a secure version of the result obtained by Langberg and Effros, on the equivalence of zero-error and $epsilon$-error regions in the network coding problem with co-located sources. Jalali and Ho exploit extractor functions to prove the weak and strong rate region equivalency for this network; however, to prove this equivalency, we develop some tools in random binning and prove the equivalency in a slightly more general setting.

In this study, the secret polar encoding and secret successive cancellation decoding algorithms are introduced; with these algorithms, secure and efficient communication can be enhanced between the honest parties. Also, the key size of the proposed polar code‐based secure channel coding system is reduced significantly compared to the existing systems. To decrease the key size, the authors employ the three following methods: (i) a new approach is proposed to save some bit‐channel indices instead of saving the generator matrix of the used polar code; (ii) the permutation and scrambling matrices are not used in this scheme; and (iii) by the help of the properties of polar codes, it does not need to save any vector as part of secret key set to generate an error vector. Moreover, the security analyses demonstrate that this system is resistant against conventional attacks on symmetric‐key code‐based cryptosystems. It means that reducing the key size of the proposed polar code‐based scheme does not affect its security level.

In this paper, we study the problem of simulating a discrete memoryless channel (DMC) from another DMC under an average-case and an exact model. We present several achievability and infeasibility results, with tight characterizations in special cases. In particular, for the exact model, we fully characterize when a binary symmetric channel can be simulated from a binary erasure channel when there is no shared randomness. We also provide infeasibility and achievability results for the simulation of a binary channel from another binary channel in the case of no shared randomness. To do this, we use the properties of Rényi capacity of a given order. We also introduce a notion of “channel diameter” which is shown to be additive and satisfy a data processing inequality.

In this paper, we investigate the index coding problem in the presence of an eavesdropper. Messages are to be sent from one transmitter to a number of legitimate receivers who have side information about the messages, and share a set of secret keys with the transmitter. To do this, the transmitter communicates to the legitimate receivers the public code C, which is also heard by the eavesdropper. We assume perfect secrecy, meaning that the eavesdropper should not be able to retrieve any information about the message set from the public communication. We study the minimum key lengths for zero-error and perfectly secure index coding problem. On one hand, this problem is a generalization of the index coding problem (and thus a difficult one). On the other hand, it is a generalization of the Shannon's cipher system. We show that a generalization of Shannon's one-time pad strategy is optimal up to a multiplicative constant, meaning that it obtains the entire boundary of the cone formed by looking at the secure rate region from the origin. This shows the optimality of the generalized one-time pad for minimizing the consumption of shared secret keys per message bits, when public communication is free (the transmitter is not charged for the rate of the public communication). Finally, we consider relaxation of the perfect secrecy and zero-error constraints to weak secrecy and asymptotically vanishing probability of error, and provide a secure version of the result, obtained by Langberg and Effros, on the equivalence of zero-error and ε-error regions in the conventional index coding problem.

In this study, the authors introduce an efficient secure channel coding (joint cryptography‐channel coding) scheme based on Latin square low‐density lattice codes (Latin square LDLCs) over unconstrained power additive white Gaussian noise channel. They benefit the properties of Latin square LDLCs to dramatically reduce the key size of the proposed scheme while having an acceptable level of security compared with previous similar schemes. To reduce the key size, they consider two approaches: (i) saving the generating sequence of parity‐check matrix of used Latin square LDLC as the part of secret key set; (ii) employing the Hermite normal form of the generator matrix of used Latin square LDLC as the encryption matrix. To provide an acceptable level of security, they consider three other strategies: (i) applying two hard problems related to lattices, i.e. shortest basis problem and closest vector problem; (ii) using a random rational vector as the perturbation (error) vector; (iii) exploiting the special joint encryption/LDLC encoding and joint decryption/LDLC decoding algorithms. Besides, the study discusses other efficiency analysis results consisting error performance and computational complexity of the proposed scheme.

The authors study the problem of secret communication over a multiple‐access channel with a common message. Here, the authors assume that two transmitters have confidential messages, which must be kept secret from the wiretapper (the second receiver), and both of them have access to a common message which can be decoded by the two receivers. The authors call this setting as multiple‐access wiretap channel with common message (MAWC‐CM). For this setting, the authors derive general inner and outer bounds on the secrecy capacity region for the discrete memoryless case and show that these bounds meet each other for a special case called the switch channel. As well, for a Gaussian version of MAWC‐CM, the authors derive inner and outer bounds on the secrecy capacity region. Providing numerical results for the Gaussian case, the authors illustrate the comparison between the derived achievable rate region and the outer bound for the considered model and the capacity region of compound multiple access channel.

This study presents a dynamic cube attack on the algorithm Grain‐v1 which has resisted all the key‐recovery attacks in the single key model. The dynamic cube attack finds the secret key by using distinguishers obtained from structural weaknesses of a cipher. The main idea of the attack lies in simplifying the cipher's output function. After making it simpler, the attack is able to exploit a distinguishing attack to recover the secret key. In this study, the authors first find the appropriate simplifications for Grain‐v1. Then, they apply their attack to the algorithm by using a new framework and a new smart choice technique for the classification of initial value bits. Finally, the authors simulate the attack to find the suitable attack parameters having 73% success rate. Their attack runs in a practical time and recovers all the key bits when the number of initialisation rounds in Grain‐v1 is reduced to 100 of 160. The attack is faster than exhaustive search by a factor of 2 38 .

One of the approaches to modify the McEliece cryptosystem to overcome its large key size is replacing binary Goppa codes with a new structured code. However, this modification makes such cryptosystems encounter some new attacks. There are a few modified McEliece cryptosystem variants which are known to be secure. One of them is the cryptosystem introduced by Baldi et al . which uses quasi‐cyclic low‐density parity check (QC‐LDPC) codes. This cryptosystem is still unbroken as no efficient attack has been reported against it since 2008. In this study, an attack has been applied to this cryptosystem which is feasible when the code length is a multiple of a power of 2. Also an important weakness of this kind of cryptosystem has been pointed out, namely utilising a too low‐weight intentional error vector. The authors have established a new security level for this cryptosystem which is applicable to other McEliece‐like cryptosystems using QC‐LDPC codes. This security level for instance is 2 9.18 times lower than previous ones in the case of n = 4 × 4096 when only one ciphertext is available. The gain of the attack in this study can be increased if more than one ciphertext is available.

Energy harvesting has been developed as an effective technology for communication systems in order to extend their lifetime. In this paper, we consider a single-user energy harvesting wireless communication system, in which arrival data and harvested energy curves are modeled as continuous functions. Our first goal is to find an offline algorithm, which maximizes the amount of data, which is transmitted to the receiver node by a given deadline. If more than one scheme exists that transmits the maximum data, we choose the one with minimum utilized energy at the transmitter node. We find this optimal algorithm, by showing its properties. Next, we propose an online algorithm for this system and obtain its performance bound.

In this paper, we study the problem of secret communication over a compound Multiple Access Channel (MAC). In this channel, we assume that one of the transmitted messages is confidential, which is only decoded by its corresponding receiver and kept secret from the other receiver. We call this proposed setting the compound MAC with a confidential message. For this model, we derive general inner and outer bounds for both imperfect and perfect secrecy conditions for the second receiver. Also, as examples, we investigate less noisy and Gaussian versions of this channel, and extend the results of the discrete memoryless version to these cases. Moreover, providing numerical examples for the Gaussian case, we illustrate the comparison between achievable rate regions of compound MAC and compound MAC with a confidential message. In addition, for the Gaussian case, we show that using cooperative jamming strategy can increase the achievable secrecy rate between the legitimate transmitter and the receiver.

In this paper, we investigate the index coding problem in the presence of an eavesdropper. Messages are to be sent from one transmitter to a number of legitimate receivers who have side information about the messages, and share a set of secret keys with the transmitter. We assume perfect secrecy, meaning that the eavesdropper should not be able to retrieve any information about the message set. This problem is a generalization of the Shannon's cipher system. We study the minimum key lengths for zero-error and perfectly secure index coding problems.

The authors propose a new technique to model the arriving energy's knowledge (AEK) in the energy harvesting (EH) communication systems. They consider a batteryless EH transmitter with the AEK non‐causally provided to it. They show that the capacity of the authors' model in general case, that is, discrete memoryless channel, can be derived through a binning scheme. This resembles a Gelfand–Pinsker type capacity formula which intuitively is the result of treating the energy as a channel state. Moreover, they investigate two especial cases of binary and Gaussian channels with the EH transmitters. In the binary symmetric channel with EH transmitter (BSCEH), their coding scheme leads to achieve the capacity of the classic binary symmetric channel (BSC). In the batteryless Gaussian channel with EH transmitter, the upper bound on the capacity is derived, and it is shown this bound is less than the capacity of the EH Gaussian channel with infinite battery.

In this study, by exploiting the properties of finite‐length polar codes, the authors introduce a physical layer encryption scheme to make secure (from a computational security perspective) and efficient communication between a sender (Alice) and a legitimate receiver (Bob) against both active and passive attacks, simultaneously. To prevent active attacks, two techniques are considered: (i) a novel method is introduced to keep the generator matrix of polar code secret from an active attacker (Oscar); (ii) a proper joint polar encoding/encryption algorithm based on the hidden generator matrix is introduced. Two additional strategies are considered against passive attacks: (i) a new method is introduced to partition the bit‐channels into good and bad bit‐channels and then the scrambled information bits are transmitted over those bit‐channels that are good for Bob but bad for a passive attacker (Eve); (ii) the secret key cryptography is implemented at the physical layer, such that Eve cannot decode the eavesdropped data without the knowledge of the secret key shared between the authorised parties. Besides, this study discusses efficiency analysis results consisting key size, error performance and computational complexity of the proposed scheme.

In this study, the authors study lossy communication of correlated sources over a multiple‐access wiretap channel (MAC‐WT). Consider a system with two transmitters, a receiver and an eavesdropper. There are two correlated sources where each of them is observed by the corresponding transmitter, separately. Each transmitter wishes to describe its source sequence to the receiver with a desired distortion. The sources need to be kept secret from the eavesdropper. They find an achievable region for the MAC‐WT with correlated sources by separation. A joint source‐channel coding scheme for the MAC‐WT is also proposed. They consider lossy communication of a bivariate Gaussian source over Gaussian MAC‐WT (GMAC‐WT). They propose a separation‐based achievable scheme for the GMAC‐WT. An achievable region for the GMAC‐WT based on uncoded transmission is also found. They compare the separate and the uncoded schemes for the symmetric GMAC‐WT, where the same constraint on the power of each transmitter is imposed and the same distortion on each source is achieved. For another case of source correlation coefficient, they compare the separate, uncoded and hybrid schemes. They obtain outer bounds to the rate‐distortion‐equivocation region of: (i) the degraded MAC‐WT where the output at the eavesdropper is a degraded version of the output at the receiver, (ii) the GMAC‐WT with independent sources and (iii) the symmetric GMAC‐WT when the correlation of the sources is maximum. Optimal regions for some cases are established.

In this study, the authors evaluate the security of the lightweight block cipher KLEIN‐64 using biclique cryptanalysis. They first point out some new weaknesses of the diffusion layer and key schedule of this algorithm. Then they exploit them to cryptanalyst the full round version of KLEIN‐64 using an asymmetric biclique. The (worst case) computations and data complexity of this cryptanalysis are 2 62.84 and 2 39 , respectively. A modified version of this cryptanalysis is also presented which is slightly faster at the expense of the data required.

Abstract A large number of random key pre‐distribution (RKD) schemes have been proposed in the literature to secure wireless sensor network applications, relying on symmetric key cryptography. However, sensor nodes are exposed to physical compromise by adversaries, who target the symmetric keys stored at each node. With the stolen keys in their possession, the adversaries are then able to compromise communication links between benign nodes. Here, the big challenge arises: how to increase resilience of RKD schemes for wireless sensor networks to node capture, while maintaining the flexibility and low‐cost features of RKD? We propose the idea of key splitting to address this problem, without the need of any special‐purpose hardware. Our key splitting scheme neither increases per‐node storage nor introduces additional computation and communication overheads. Nevertheless, it can achieve better connectivity. More importantly, it significantly increases resilience to node compromise, when the adversary does not have overwhelming computational power. Copyright © 2014 John Wiley & Sons, Ltd.

In this paper, we study the problem of channel simulation via interactive communication, known as the coordination capacity, in a two-terminal network. We assume that two terminals observe independent identically distributed (i.i.d.) copies of two random variables and would like to generate i.i.d. copies of two other random variables jointly distributed with the observed random variables. The terminals are provided with two-way communication links, and shared common randomness, all at limited rates. Two special cases of this problem are the interactive function computation studied by Ma and Ishwar, and the tradeoff curve between one-way communication and shared randomness studied by Cuff. The latter work had inspired Gohari and Anantharam to study the general problem of channel simulation via interactive communication stated above. However, only inner and outer bounds for the special case of no shared randomness were obtained in their work. In this paper, we settle this problem by providing an exact computable characterization of the multiround problem. To show this we employ the technique of output statistics of random binning that has been recently developed by the authors.

In this paper, we study the problem of secret communication over a Compound Multiple Access Channel (MAC). In this channel, we assume that one of the transmitted messages is confidential that is only decoded by its corresponding receiver and kept secret from the other receiver. For this proposed setting (compound MAC with confidential messages), we derive general inner and outer bounds on the secrecy capacity region. Also, as examples, we investigate `Less noisy' and `Gaussian' versions of this channel, and extend the results of the discrete memoryless version to these cases. Moreover, providing numerical examples for the Gaussian case, we illustrate the comparison between achievable rate regions of compound MAC and compound MAC with confidential messages.

In this study, the three‐user interference channel (IFC) with common information is considered, where each receiver decode not only the private message from the intended transmitter but also the common messages from the non‐intended transmitters by applying a simultaneous decoding scheme. An achievable rate region is presented using rate splitting and superposition encoding at the transmitters and simultaneous joint decoding at the receivers in which the transmitters cooperatively send the split messages which allows the interference cancellation at the receivers. The implicit form of the achievable rate region is also extended to K ‐user IFC with common information. Finally the inner bound derived for the three‐user discrete memoryless IFC with common information is generalised to the Gaussian case and is evaluated in a numerical example.

The authors study a two‐user state‐dependent generalised multiple‐access channel (GMAC) with correlated states. It is assumed that each encoder has ‘non‐causal’ access to channel state information (CSI). They develop an achievable rate region by employing rate‐splitting, block Markov encoding, Gelfand–Pinsker multicoding, superposition coding and joint typicality decoding. In the proposed scheme, the encoders use a partial decoding strategy to collaborate in the next block, and the receiver uses a backward decoding strategy with joint unique decoding at each stage. The author's achievable rate region includes several previously known regions proposed in the literature for different scenarios of multiple‐access and relay channels. Then, they consider two Gaussian GMACs with additive interference. In the first model, they assume that the interference is known non‐causally at both of the encoders and construct a multi‐layer Costa precoding scheme that removes ‘completely’ the effect of the interference. In the second model, they consider a doubly dirty Gaussian GMAC in which each of interferences is known non‐causally only at one encoder. They derive an inner bound and analyse the achievable rate region for the latter model and interestingly prove that if one of the encoders knows the full CSI, there exists an achievable rate region which is ‘independent’ of the power of interference.

In this study, the authors consider the secrecy of a one‐receiver, two‐eavesdropper broadcast channel (BC) with three degraded message sets. Consider a three‐receiver BC with three messages, where the first message is decoded by all the receivers. The second message is decoded by the first and the second receivers and is to be kept secret from the third receiver. The third message is decoded by the first receiver and is to be kept secret from the second and the third receivers. The authors consider the imperfect secrecy condition at the second receiver, that is, it is allowed to partially decode the third message. However, the perfect secrecy condition at the third receiver, does not allow it to decode the confidential messages. The coding scheme for this model requires decoding strategy for finding the messages at different destinations. The authors propose a coding scheme which uses indirect decoding. The authors also obtain an outer bound and use it to determine the secrecy capacity region of some classes of one‐receiver, two‐eavesdropper BCs with three degraded message sets. The authors extend our results to the Gaussian case and evaluate the achievable region.

In a multistage secret sharing (MSSS) scheme, the authorised subsets of participants could recover a number of secrets in different stages. A one‐stage multisecret sharing (OSMSS) scheme is a special case of MSSS schemes in which all the secrets are recovered simultaneously. In these schemes, in addition to the individual shares, the dealer should provide the participants with a number of public values associated with the secrets. The less the number of public values, the more efficient is the scheme. It is desired that the MSSS and OSMSS schemes provide computational security. In this study, the authors show that in the OSMSS schemes any unauthorised coalition of the participants can reduce the uncertainty of the secrets. In addition, in MSSS schemes recovering a secret causes reducing uncertainty of the unrecovered secrets. Furthermore, by introducing a new multi‐use MSSS scheme based on weil pairing, they reduce the number of public values comparing with the previous schemes.

In this paper, we present a framework for biclique cryptanalysis of block ciphers which extremely requires a low amount of data. To that end, we enjoy a new representation of biclique attack based on a new concept of cutset that describes our attack more clearly. Then, an algorithm for choosing two differential characteristics is presented to simultaneously minimize the data complexity and control the computational complexity. Then, we characterize those block ciphers that are vulnerable to this technique and among them, we apply this attack on lightweight block ciphers Piccolo-80, Piccolo-128, and HIGHT. The data complexity of these attacks is only 16-plaintext-ciphertext pairs, which is considerably less than the existing cryptanalytic results. In all the attacks, the computational complexity remains the same as the previous ones or even it is slightly improved.

This paper introduces a new and ubiquitous framework for establishing achievability results in network information theory problems. The framework uses random binning arguments and is based on a duality between channel and source coding problems. Furthermore, the framework uses pmf approximation arguments instead of counting and typicality. This allows for proving coordination and strong secrecy problems, where certain statistical conditions on the distribution of random variables need to be satisfied. These statistical conditions include independence between messages and eavesdropper's observations in secrecy problems and closeness to a certain distribution (usually, i.i.d. distribution) in coordination problems. One important feature of the framework is to enable one to add an eavesdropper and obtain a result on the secrecy rates for free. We make a case for generality of the framework by studying examples in a variety of settings including channel coding, lossy source coding, joint source-channel coding, coordination, strong secrecy, feedback, and relaying. In particular, by investigating the framework for the lossy source coding problem over broadcast channel, it is shown that the new framework provides a simple alternative scheme to the hybrid coding scheme. In addition, new results on secrecy rate region (under strong secrecy criterion) of wiretap broadcast channel and wiretap relay channel are derived. In a set of accompanied papers, we have shown the usefulness of the framework to establish achievability results for coordination problems, including interactive channel simulation, coordination via relay and channel simulation via another channel.

In this paper, we investigate the problem of the empirical coordination in a triangular multiterminal network. A triangular multiterminal network consists of three terminals where two terminals observe two external i.i.d correlated sequences. The third terminal wishes to generate a sequence with desired empirical joint distribution. For this problem, we derive inner and outer bounds on the empirical coordination capacity region. It is shown that the capacity region of the degraded source network and the inner and outer bounds on the capacity region of the cascade multiterminal network can be directly obtained from our inner and outer bounds. For a cipher system, we establish key distribution over a network with a reliable terminal, using the results of the empirical coordination. As another example, the problem of rate distortion in the triangular multiterminal network is discussed in which a distributed doubly symmetric binary source is available.

In this paper, we consider lossy source transmission over a Multiple Access WireTap Channel (MAC-WT). In this model, there are two correlated sources, each of them is available at the corresponding encoder. The receiver tries to reconstruct both sources with desired distortions. The sources should be kept secret from an eavesdropper. We propose a joint source-channel scheme for the MAC-WT. In this scheme, each source sequence is mapped to common and private codewords. The common codeword can be decoded by the eavesdropper. The private codeword needs to be kept secret from the eavesdropper by using Wyner's wiretap coding. We also discuss some special cases of the proposed scheme.

This paper proposes a novel technique to prove a one-shot version of achievability results in network information theory. The technique is not based on covering and packing lemmas. In this technique, we use a stochastic encoder and decoder with a particular structure for coding that resembles both the ML and the joint-typicality coders. Although stochastic encoders and decoders do not usually enhance the capacity region, their use simplifies the analysis. The Jensen inequality lies at the heart of error analysis, which enables us to deal with the expectation of many terms coming from stochastic encoders and decoders at once. The technique is illustrated via four examples: point-to-point channel coding, Gelfand-Pinsker, broadcast channel and Berger-Tung problem of distributed lossy compression. Applying the one-shot result for the memoryless broadcast channel in the asymptotic case, we get the entire region of Marton's inner bound without any need for time-sharing. Also, these results are employed in conjunction with multi-dimensional berry-esseen CLT to derive new regions for finite-blocklength regime of Gelfand-Pinsker.

In this paper we develop a finite blocklength version of the Output Statistics of Random Binning (OSRB) framework. This framework is shown to be optimal in the point-to-point case. New second order regions for broadcast channel and wiretap channel with strong secrecy criterion are derived.

In this paper, we study the problem of simulating a DMC channel from another DMC channel. We assume that the input to the channel we are simulating is i.i.d. and that the transmitter and receivers are provided with common randomness at limited rates. We prove bounds for simulating point-to-point, MAC and broadcast channels. As a special case, we recover the achievability part of the result of Cuff for point-to-point channel simulation via a noiseless link and shared randomness.

In this paper, we investigate reliable transmission of three correlated discrete memoryless sources over a two-relay network. In our considered model, one of the sources is available at the sender whereas, the other two sources are known to the first and the second relay. We present both joint and separate source-channel coding schemes, and derive the corresponding sets of sufficient conditions for reliable sources transmission. The manner of cooperation in both schemes is Decode-and-Forward strategy. In the joint approach, we generalize the correlation preserving mapping technique to our model using nested backward decoding. Our proposed separate approach is based on Slepian-Wolf source coding and irregular encoding/successive decoding strategy. Furthermore, we obtain necessary conditions for reliable sources transmission over the network. Our results can be reduced to the several known results in the literature.

Since low-cost RFID systems are applied in ubiquitous varied applications, privacy and security of their users became a great concern. Therefore, the various authentication protocols have been proposed. In this paper, we inspect the three new-found RFID authentication protocols based on quadratic residue property via one of the well-organized formal RFID privacy models instead of intuitive analysis. We formally prove that modular squaring is the suitable technique to guarantee RFID authentication protocols against backward traceability. Then, the flaws are alleviated to resist traceability attacks.

For a fading full‐duplex decode‐and‐forward relay channel, the authors analytically derive optimum power allocation schemes subject to individual power constraints at the source and the relay. The authors prove that the problem is a convex optimisation problem over the feasible power set, and by proposing a systematic technique to solve min–max problems, optimum power allocations are derived in closed‐forms. Finally, for a Rayleigh‐fading channel model, optimum power allocations are derived and the respective achievable rate and an upper bound are evaluated. The implications of the derived theoretical results are discussed through some graphs.

A secret key agreement framework involving three users is considered in which each of the users 1 and 2 intends to share a secret key with user 3 and users 1 and 2 are eavesdroppers with respect to each other. There is a generalized discrete memoryless multiple access channel (GDMMAC) from users 1 and 2 to user 3 where the three users receive outputs from the channel. Furthermore, there is a feedback channel from user 3 to users 1 and 2 through which user 3 sends information extracted from the received output from the GDMMAC to increase the key rates. We consider both noiseless and noisy feedback. In the case of noiseless feedback, a public channel of unlimited capacity from user 3 to users 1 and 2 is used only once. In the case of noisy feedback, a noisy broadcast channel (BC) from user 3 to users 1 and 2 can be repeatedly used, like GDMMAC. In both setups, inner bounds of the secret key capacity region are derived. The secret key capacity region is derived in some special cases where the channel inputs and outputs form Markov chains in certain orders. For illustration, the corresponding results are also derived and discussed for Gaussian channels. The cases with noiseless feedback, noisy feedback, and no feedback at all are compared with each other.

ABSTRACT Ubiquitousness of Radio Frequency Identification (RFID) systems with inherent weaknesses has been a cause of concern about their privacy and security. Therefore, secure protocols are essentially necessary for the RFID tags to guarantee privacy and authentication among them and the reader. This paper inspects privacy in the RFID systems. First, we survey four new‐found RFID authentication protocols, and then, their weaknesses in formal privacy model are analyzed. Although the authors of the schemes claimed that their protocols completely resist privacy attacks, we formally prove that all of them suffer from the family of traceability attacks. Furthermore, not only are the four improved protocols proposed to prevent the aforementioned attacks, but also we provide formal analysis to guarantee the security and privacy of the proposed enhancements. Copyright © 2012 John Wiley & Sons, Ltd.

Privacy is faced with serious challenges in the ubiquitous computing world. In order to handle this problem, some researchers in recent years have focused on design and analysis of privacy-friendly ultralightweight authentication protocols. Although the majority of these schemes have been broken to a greater or lesser extent, most of these attacks are based on ad-hoc methods that are not extensible to a large class of ultralightweight protocols. So this research area still suffers from the lack of structured cryptanalysis and evaluation methods. In this paper, we introduce new frameworks for full disclosure attacks on ultralightweight authentication protocols based on new concepts of recursive linear and recursive differential cryptanalysis. The recursive linear attack is passive, deterministic, and requires only a single authentication session, if it can be applied successfully. The recursive differential attack is more powerful and can be applied to the protocols on which the linear attack may not work. This attack is probabilistic, active in the sense that the attacker suffices only to block some specific messages, and requires a few authentication sessions. Having introduced these frameworks in a general view, we apply them on some well-known ultralightweight protocols. The first attack can retrieve all the secret data of Yeh and SLMAP authentication protocols and the second one can retrieve all the secret data of LMAP++, SASI, and David-Prasad authentication protocols.

In this paper, we study the one-receiver two-eavesdropper Broadcast Channel (BC) with three degraded message sets. A common message is sent to three receivers. Another message is sent to the first and second receivers and needs to be kept secret from the third receiver (second eavesdropper). The third message is sent to the first receiver and needs to be kept secret from the second and third receivers (first and second eavesdroppers). First, we consider perfect secrecy conditions at the eavesdroppers, where we find an achievable perfect secrecy region. In the achievability scheme, we use superposition coding which divides the available randomness into different levels. These levels are used to mislead the eavesdroppers. The proposed coding scheme determines the perfect secrecy capacity region of the one-receiver two-eavesdropper BC with three degraded message sets, when the receivers exhibit a degradedness order. Next, we find an achievable rate-equivocation region using the rate splitting technique and indirect decoding. We show that for the two-receiver one-eavesdropper BC with three degraded message sets where we relax the secrecy condition at the second receiver, our coding scheme is optimal when the second receiver is a degraded version of the first receiver and it is less noisy than the third receiver.

A large number of Wireless Sensor Network (WSN) security schemes have been proposed in the literature, relying primarily on symmetric key cryptography. To enable those, Random Key pre-Distribution (RKD) systems have been widely accepted. However, WSN nodes are vulnerable to physical compromise. Capturing one or more nodes operating with RKD would give the adversary keys to compromise communication of other benign nodes. Thus the challenge is to enhance resilience of WSN to node capture, while maintaining the flexibility and low-cost features of RKD. We address this problem, without any special-purpose hardware, proposing a new and simple idea: key splitting. Our scheme does not increase per-node storage, and computation and communication overheads, and it can increase connectivity. More important, it achieves a significant increase in resilience to compromise compared to the state of the art, notably when the adversary does not have overwhelming computational power.

In this paper, we study the problem of coordinating two nodes which can only exchange information via a relay at limited rates. The nodes are allowed to do a two-round interactive two-way communication with the relay, after which they should be able to generate i.i.d. copies of two random variables with a given joint distribution within a vanishing total variation distance. We prove inner and outer bounds on the coordination capacity region for this problem. Our inner bound is proved using the technique of “output statistics of random binning" that has recently been developed by Yassaee, et al.

We investigate the secrecy capacity region of 2-receiver, 1-eavesdropper Broadcast Channel (BC) with two causal states and conferencing decoders. The encoder sends two messages, one of them for both legitimate receivers and the other one for the first legitimate receiver. It keeps these messages secret from the eavesdropper. Each state is causally available at the corresponding receiver, while both states are known causally at the encoder. Each receiver wishes to send the state which is not available at the other receiver, through a noiseless link with limited capacity. We find an inner bound on the secrecy capacity region of this channel. The achievability scheme employs block Markov coding and Shannon strategy for channels with state. In each block, we make use of the states to generate two keys which will be used in the next block. The idea is to utilize the cooperation of both receivers to recover both keys at each receiver while ensuring secrecy. We also establish an outer bound on the secrecy capacity region of the 2-rec, 1-eav. BC with Causal Channel State Information (CCSI) and conferencing. We prove that the proposed bounds coincide for a special case.

We study the reliable transmission of correlated sources over the relay channel. One of the sources is available at the sender while the other one is known to the relay. The receiver wishes to reconstruct both sources. We find necessary and sufficient conditions for optimal separation of source and channel codes. The coding scheme is based on the combination of the Slepian-Wolf source coding and Partial Decode-and-Forward (PDF) strategy. In this scheme, the relay partially decodes the message transmitted by the sender. We also consider the semi-deterministic relay channel where the output at the relay is a deterministic function of inputs from the sender and the relay. For the transmission of a single source over the semi-deterministic relay channel with correlated side information at the relay, the proposed conditions coincide. We also find necessary and sufficient conditions for the transmission of sources over the degraded relay channel where the output at the receiver is a degraded version of the output at the relay.

This paper presents a new and ubiquitous framework for establishing achievability results in network information theory (NIT) problems. The framework is used to prove various new results. To express the main tool, consider a set of discrete memoryless correlated sources (DMCS). Assume that each source (except one, Zn) is randomly binned at a finite rate. We find sufficient conditions on these rates such that the bin indices are nearly mutually independent of each other and of Zn. This is used in conjunction with the Slepian-Wolf (S-W) result to set up the framework. We begin by illustrating this method via examples from channel coding and rate-distortion (or covering problems). Next, we use the framework to prove a new result on the lossy transmission of a source over a broadcast channel. We also prove a new lower bound to a three receiver wiretap broadcast channel under a strong secrecy criterion. We observe that we can directly prove the strong notion of secrecy without resorting to the common techniques, e.g., the leftover hash lemma. We have also used our technique to solve the problem of two-node interactive channel simulation and the problem of coordination via a relay.

In this paper, we study the problem of channel simulation via interactive communication, known as the coordination capacity, in a two-terminal network. We assume that two terminals observe i.i.d. copies of two random variables and would like to generate i.i.d. copies of two other random variables jointly distributed with the observed random variables. The terminals are provided with two-way communication links, and shared common randomness, all at limited rates. Two special cases of this problem are the interactive function computation studied by Ma and Ishwar, and the tradeoff curve between one-way communication and shared randomness studied by Cuff. The latter work had inspired Gohari and Anantharam to study the general problem of channel simulation via interactive communication stated above. However only inner and outer bounds for the special case of no shared randomness were obtained in their work. In this paper we settle this problem by providing an exact computable characterization of the multi-round problem. To show this we employ the technique of “output statistics of random binning” that has been recently developed by the authors.

This paper introduces a new applicable Gaussian wiretap channel with side information. In this channel, the state of the channel to the wiretapper is separated from the main channel's one. It means that the legitimate receiver and the wiretapper are listening to the transmitted signal through the different channels with different channel states which may have some correlation to each other. The state of the main channel, is assumed to be known at the transmitter, helps the sender to encrypt its messages. The achievable equivocation-rate region for this model is drived in the Gaussian case and the results are reduced to the previous works as special cases.

In this paper the Output Statistics of Random Binning (OSRB) framework is used to prove a new inner bound for the problem of secure channel simulation. Our results subsume some recent results on the secure function computation. We also provide an achievability result for the problem of simultaneously simulating a channel and creating a shared secret key. A special case of this result generalizes the lower bound of Gohari and Anantharam on the source model to include constraints on the rates of the public discussion.

In this paper, lattice based coding is used over two-user Gaussian state-dependent multiple access channel with common message for two channel models. First, it is assumed that the additive channel interference is noncausally known at both encoders. Exploiting a lattice encoding and decoding scheme, the effect of the interference is completely removed and the capacity region is achieved. Then, the multiple access channel with two additive interferences is considered in the case, where each interference is known noncausally to the associated transmitter. A pure lattice based encoding and decoding structure is proposed and an inner bound on the capacity region is derived which is valid for the entire range of channel signal to noise ratio and powers of interferences.

In this study, a two-user discrete memoryless multiple-access channel with two correlated states known non-causally at the corresponding encoder is considered. Each encoder transmits a message independent of the other encoder's and tries to cooperate with it. To consider cooperative encoders, it is assumed that each encoder strictly-causally receives and finds out the other encoder's transmitted signals and tries to cooperate with the other encoder by transmitting its message. A special case is also studied in which the common part of the states is known at the both encoders, resulting in a larger rate region. For these two scenarios, achievable rate regions are derived using a combination of block-Markov and Gel'fand-Pinsker coding techniques, and outer bounds are also established. For the second scenario, the achievable rate region of the Gaussian model is derived, and some implications of the results are discussed.

This study investigates the capacity region of a three-user cognitive radio network with two primary users and one cognitive user. A three-user cognitive interference channel (C-IFC) is proposed by considering a three-user interference channel (IFC) where one of the transmitters has cognitive capabilities and knows the messages of the other two transmitters in a non-causal manner. First, two inner bounds on the capacity region of the three-user C-IFC are obtained based on using the schemes which allow all receivers to decode all messages with two different orders. Next, two sets of conditions are derived, under which the capacity region of the proposed model coincides with the capacity region of a three-user C-IFC in which all three messages are required at all receivers. Under these conditions, referred to as strong interference conditions, the capacity regions for the proposed three-user C-IFC are characterised. Moreover, the Gaussian three-user C-IFC is considered and the capacity results are derived for the Gaussian case. Some numerical examples are also provided.

Many applications that utilise wireless sensor networks (WSNs) require essentially secure communication. However, WSNs suffer from some inherent weaknesses because of restricted communication and hardware capabilities. Key management is the crucial important building block for all security goals in WSNs. Most existing researches tried to assign keys assuming homogeneous network architecture. Recently, a few key management models for heterogeneous WSNs have been proposed. In this study, the authors propose a dynamic key management framework based on elliptical curve cryptography and signcryption method for heterogeneous WSNs. The proposed scheme has network scalability and sensor node (SN) mobility especially in liquid environments. Moreover, both periodic authentication and a new registration mechanism are proposed through prevention of SN compromise. The authors analyse some of the more seminal hierarchical heterogeneous WSN key management schemes and compare them with the proposed scheme. On comparing the proposed scheme with the more seminal hierarchical heterogeneous WSN key management schemes, the proposed framework individually proves to be better in terms of communication, computation and key storage.

A source model including four terminals is considered, where three simultaneously generating three types of keys are intended. Terminals 1, 2 and 3 wish to share a common key, the secret key, which should be kept secret from terminal 4 and simultaneously terminals 1 and 2 intend to share a private key with terminal 3, which should be kept secret from each other. Also, all the keys should be concealed from terminal 4 (the external wiretapper). The authors assume that all terminals including the external wiretapper have access to distinct correlated i.i.d. sources; there is also a noiseless public channel with unlimited capacity among the terminals. The authors have investigated the model on two scenarios of key sharing depending on the direction of the public channel. Rate regions of the keys are derived. It is shown that in some special cases the inner and outer bounds of the capacity regions coincide and the capacity regions are derived.

In this paper, taking into account the effect of link delays, we investigate the capacity region of the cognitive interference channel (C-IFC), where cognition can be obtained from either causal or noncausal generalized feedback. For this purpose, we introduce the causal C-IFC with delay (CC-IFC-WD) in which the cognitive user's transmission can depend onLfuture received symbols as well as the past ones. We show that the CC-IFC-WD model is equivalent to a classical causal C-IFC (CC-IFC) with link delays. Moreover, CC-IFC-WD extends both genie-aided and causal cognitive radio channels and bridges the gap between them. First, we derive an outer bound on the capacity region for the arbitrary value ofLand specialize this general outer bound to the strong interference case. Then, under strong interference conditions, we tighten the outer bound. To derive the achievable rate regions, we concentrate on three special cases: 1) classical CC-IFC (L=0); 2) CC-IFC without delay (L=1) ; and 3) CC-IFC with unlimited look ahead in which the cognitive user noncausally knows its entire received sequence. In each case, we obtain a new inner bound on the capacity region. The derived achievable rate regions under special conditions reduce to several previously known results. Moreover, we show that the coding strategy which we use to derive an achievable rate region for the classical CC-IFC achieves the capacity for the classes of degraded and semideterministic classical CC-IFC under strong interference conditions. Furthermore, we extend our achievable rate regions to the Gaussian case. Providing some numerical examples for Gaussian CC-IFC-WD, we compare the performances of the different strategies and investigate the rate gain of the cognitive link for different delay values. We show that one can achieve larger rate regions in the “without delay” and “unlimited look-ahead” cases than in the classical CC-IFC; this improvement is likely due to the fact that, in the former two cases, the cognitive user can cooperate more effectively with the primary user by knowing the current and future received symbols.

Performance of routing is severely degraded when misbehaving nodes drop packets instead of properly forwarding them. In this paper, we propose a Game-Theoretic Adaptive Multipath Routing (GTAMR) protocol to detect and punish selfish or malicious nodes which try to drop information packets in routing phase and defend against collaborative attacks in which nodes try to disrupt communication or save their power. Our proposed algorithm outranks previous schemes because it is resilient against attacks in which more than one node coordinate their misbehavior and can be used in networks which wireless nodes use directional antennas. We then propose a game theoretic strategy, ERTFT, for nodes to promote cooperation. In comparison with other proposed TFT-like strategies, ours is resilient to systematic errors in detection of selfish nodes and does not lead to unending death spirals.

Security techniques have been designed to obtain certain objectives. One of the most important objectives all security mechanisms try to achieve is the availability, which insures that network services are available to various entities in the network when required. But there has not been any certain parameter to measure this objective in network. In this paper we consider availability as a security parameter in ad-hoc networks. However this parameter can be used in other networks as well. We also present the connectivity coefficient of nodes in a network which shows how important is a node in a network and how much damage is caused if a certain node is compromised.

In this paper, we present a new method for variable elimination in systems of inequalities which is much faster than the Fourier-Motzkin Elimination (FME) method. In our method, a linear Diophantine problem is introduced which is dual to the original problem. The new Diophantine system is then solved, and the final result is calculated by finding the dual system of inequalities. This new method uses the algorithm Normaliz to find the Hilbert basis of the solution space of the given Diophantine problem. We introduce a problem in the interference channel with multiple nodes and solve it with this new method. Next, we generalize our method to all problems involving FME and compare the method with the previous method. Our method has many advantages in comparison to the previous method. It does not produce many of the redundant answers of the FME method. It also solves the whole problem in one step whereas the previous method uses a step by step approach in eliminating each auxiliary variable.

In this paper, we consider the 3-receiver broadcast channel with one common and two confidential messages. One of the confidential messages is sent to the first and second receivers and kept secret from the third receiver (eavesdropper). The other confidential message is sent to the first receiver and kept secret from the second and third receivers (eavesdroppers). The common message is decoded by all receivers. We study some special cases of the model and determine their secrecy capacity regions.

In this paper, we consider the reliable transmission of correlated sources over the relay channel. The destination wishes to find a lossless reconstruction of both sources. We find the sufficient conditions under which the relay can partially cooperate with the sender to transmit the sources to the destination. The achievability scheme is based on regular encoding/backward decoding strategy. The proposed region includes the known region for multiple-access channel with correlated sources and the achievable rate of relay channel with partial decode-and-forward strategy, as special cases. A class of deterministic relay channels is considered. It is shown that the error-free transmission of correlated sources is possible over this channel, using the proposed joint source-channel coding scheme.

In this paper, the effect of using an insecure and noiseless feedback channel in increasing secret key rates is investigated. There is a generalized discrete memoryless multiple access channel (GDMMAC) between two transmitters and a receiver where, in addition to the receiver, both of the transmitters receive noisy channel outputs. Furthermore, an insecure and noiseless feedback channel exists from the receiver to the transmitters. Each of the transmitters intends to share a secret key with the receiver while keeping it concealed from the other transmitter. For this setup, an inner bound of the secret key capacity region is derived. For some special cases, the secret key capacity region is obtained, and the effect of the feedback channel usage is discussed through a binary-erasure example as well as in the Gaussian case.

In this paper, a two-user discrete memoryless multiple-access channel (DM-MAC) with correlated channel states, each known at one of the encoders is considered, in which each encoder transmits independent messages and tries to cooperate with the other one. To consider cooperating encoders, it is assumed that each encoder strictly-causally receives and learns the other encoder's transmitted symbols and tries to cooperate with the other encoder by transmitting its message. Next, we study this channel in a special case; we assume that the common part of both states is known at both, hence encoders use this opportunity to get better rate region. For these scenarios, an achievable rate region is derived based on a combination of block-Markov encoding and Gel'fand-Pinsker coding techniques. Furthermore, the achievable rate region is established for the Gaussian channel, and it is shown that the capacity region is achieved in certain circumstances.

Multi-dimensional spatial analysis of image pixels have not been much investigated for the steganalysis of the LSB Steganographic methods. Pixel distribution based steganalysis methods could be thwarted by intelligently compensating statistical characteristics of image pixels, as reported in several papers. Simple LSB replacement methods have been improved by introducing smarter LSB embedding approaches, e.g. LSB matching and LSB+ methods, but they are basically the same in the sense of the LSB alteration. A new analytical method to detect LSB stego images is proposed in this paper. Our approach is based on the relative locations of image pixels that are essentially changed in an LSB embedding system. Furthermore, we introduce some new statistical features including “local entropies sum” and “clouds min sum” to achieve a higher performance. Simulation results show that our proposed approach outperforms some well-known LSB steganalysis methods, in terms of detection accuracy and the embedding rate estimation.

The authors consider ‘partially’ and ‘fully cooperative’ state-dependent relay broadcast channels (RBCs), where partial channel state information (CSI) is available at the nodes causally. First, the authors derive an achievable rate region for general discrete memoryless partially cooperative RBC (PC-RBC) with partial causal CSI, by exploiting superposition coding at the source, decode-and-forward scheme at the relay and Shannon's strategy at the source and the relay. Then, they establish the capacity region of the discrete memoryless physically degraded PC-RBC with partial causal CSI. They also characterise the capacity region of discrete memoryless PC-RBC with feedback and partial causal CSI, and show that feedback does not affect the capacity region of the physically degraded channel. Moreover, for the fully cooperative RBC (FC-RBC) with partial causal CSI the authors obtain the same results as for the state-dependent PC-RBC. The authors' results subsume the previously known results for the degraded broadcast and relay channels with causal CSI. Finally, they extend their achievable rate regions to the Gaussian cases. Providing some numerical examples for the Gaussian cases, they compare the achievable rate regions derived for different situations.

A source model for secret key generation between terminals is considered. Two users, namely users 1 and 2, at one side communicate with another user, namely user 3, while at the other side via a public channel where three users can observe i.i.d. outputs of correlated sources. Each of users 1 and 2 intends to share a secret key with user 3 where user 1 acts as a wiretapper for user 2 and vice versa. In this model, two situations are considered: communication from users 1 and 2 to user 3 (the forward key strategy) and from user 3 to users 1 and 2 (the backward key strategy). In both situations, the goal is sharing a secret key between user 1 and user 3 while leaking no effective information about that key to user 2, and simultaneously, sharing another secret key between user 2 and user 3 while leaking no effective information about the latter key to user 1. This model is motivated by wireless communications when considering user 3 as a base station and users 1 and 2 as network users. For both the forward and backward key strategies, inner and outer bounds of secret key capacity regions are derived. In special situations where one of users 1 and 2 is only interested in wiretapping and not key sharing, the results agree with that of Ahlswede and Csiszar. Also, the authors investigate some special cases in which the inner bound coincides with the outer bound and secret key capacity region is deduced.

In this paper, a generalized multiple access channel (MAC) model for secret key sharing between three terminals is considered. In this model, there are two transmitters and a receiver where all three terminals receive noisy channel outputs. In addition, there is a one-way public channel from the transmitters to the receiver. Each of the transmitters intends to share a secret key with the receiver by using the MAC and the public channel, where the transmitters are eavesdroppers with respect to each other. Two strategies for secret key sharing are considered, namely, the pregenerated key strategy and the two-stage key strategy. For both of them, inner and outer bounds of the secret key capacity region are derived. Furthermore, the effect of the public channel is discussed and the two strategies are compared. In both strategies, it is assumed that the channel outputs at the transmitters are only used for eavesdropping and not as inputs to the encoders. The effect of this assumption in the presence of the public channel is analyzed for some Gaussian MACs.

A symmetric semideterministic relay network is introduced, generalizing Aref networks. In the considered model, there is no interference at the relays, but the links from the source and the relays to the sink are interfering and nondeterministic. An achievable rate is determined for an arbitrary number of relays, based on symmetric relaying and simultaneous partial and backward decoding at the sink. The information expressions of the achievable rate match those of the standard cut-set bound, but the set of probability distributions is substantially different. We also study a wireless example of the defined network where nondeterministic links are replaced with fading AWGN channels, and obtain its ergodic capacity with phase fading when phase information is locally available at the sink.

This paper investigates the capacity problem for some multiple-access scenarios with cooperative transmitters. First, a general Multiple-Access Channel (MAC) with common information, i.e., a scenario where p transmitters send private messages and also a common message to q receivers and each receiver decodes all of the messages, is considered. The capacity region of the discrete memoryless channel is characterized. Then, the general Gaussian fading MAC with common information wherein partial Channel State Information (CSI) is available at the transmitters (CSIT) and perfect CSI is available at the receivers (CSIR) is investigated. A coding theorem is proved for this model that yields an exact characterization of the throughput capacity region. Finally, a two-transmitter/one-receiver Gaussian fading MAC with conferencing encoders with partial CSIT and perfect CSIR is studied and its capacity region is determined. For the Gaussian fading models with CSIR only (transmitters have no access to CSIT), some numerical examples and simulation results are provided for Rayleigh fading.

This paper deals with the problem of multicasting a set of discrete memoryless correlated sources (DMCS) over a cooperative relay network. Necessary conditions with cut-set interpretation are presented. A Joint source-Wyner–Ziv encoding/sliding window decoding scheme is proposed, in which decoding at each receiver is done with respect to an ordered partition of other nodes. For each ordered partition a set of feasibility constraints is derived. Then, utilizing the submodular property of the entropy function and a novel geometrical approach, the results of different ordered partitions are consolidated, which lead to sufficient conditions for our problem. The proposed scheme achieves operational separation between source coding and channel coding. It is shown that sufficient conditions are indeed necessary conditions in two special cooperative networks, namely, Aref network and finite-field deterministic network. Also, in Gaussian cooperative networks, it is shown that reliable transmission of all DMCS whose Slepian–Wolf region intersects the cut-set bound region within a constant number of bits, is feasible. In particular, all results of the paper are specialized to obtain an achievable rate region for cooperative relay networks which includes relay networks and two-way relay networks.

Trivium is a hardware profile finalist of eSTREAM project. It is a synchronous bit-oriented stream cipher. The cipher's internal state has 288 bits. Bivium is a simplified version of Trivium with a smaller internal state. Both algorithms provide the security level of 80 bits. In this paper we introduce a guess and determine attack on Trivium and Bivium. In our method, we first find the linear approximations for the updating functions. Then by using these approximations, we build a system of linear equations and internal state variables. In order to solve the system, some bits of the internal state should be guessed. Our attack on Trivium is not successful because of the large length of internal state therefore it is resistant to the method. It's complexity is of order O(290.67). But for recovering the state of Bivium, we need to guess only 27.55 bits and other bits will be determined. In order to complete the attack 243.99bits of key stream are needed. The complexity of the attack on Bivium is O(227.55), which is an improvement to the previous guess and determine attack with a complexity of order O(252.3).

In this paper, we introduce a discrete memoryless State-Dependent Relay Channel with Private Messages (SD-RCPM) as a generalization of the state-dependent relay channel. We investigate two main cases: SD-RCPM with non-causal Channel State Information (CSI), and SD-RCPM with causal CSI. In each case, it is assumed that partial CSI is available at the source and relay. For non-causal case, we establish an achievable rate region using Gel'fand-Pinsker type coding scheme at the nodes informed of CSI, and Compress-and-Forward (CF) scheme at the relay. Using Shannon's strategy and CF scheme, an achievable rate region for causal case is obtained. As an example, the Gaussian version of SD-RCPM is considered, and an achievable rate region for Gaussian SD-RCPM with non-causal perfect CSI only at the source, is derived. Providing numerical examples, we illustrate the comparison between achievable rate regions derived using CF and Decode-and-Forward (DF) schemes.

In this paper, we investigate the performance of two strategies: simultaneous sliding window decoding (SimSlide) and simultaneous backward decoding (SimBack) when generalizing partial decode-and-forward to the relay networks. We show that these two methods yield the same achievable rates for relay networks but in comparison with sequential decoding, they yield higher rates. This is due to the fact that simultaneously decoding the different parts of the source message yields fewer bounds and this ultimately results a comprehensive and higher rate. We also introduce a special class of semi-deterministic relay networks and obtain its capacity by the proposed achievable rate.

In this paper, we study the two-user Gaussian fading Multiple Access Channel (MAC) with cooperative encoders. Two different scenarios are studied: the Gaussian fading MAC with a common message, and the Gaussian fading MAC with conferencing encoders. The throughput capacity region of these channels with partial Channel State Information (CSI) at the transmitters (CSIT) and perfect CSI at the receiver (CSIR) is established. For the Gaussian fading systems with only CSIR (transmitters have no access to CSIT), some numerical examples and simulation results are provided for Rayleigh fading models.

In this paper, we obtain an outer bound on the capacity region of the Broadcast-Relay-Channel (BRC). BRC is a four node network with one source, one relay and two destinations. To the best of our knowledge, this work represents the first effort to find an outer bound on the capacity region of the BRC. In the proof, we jointly utilize the ideas of the outer bounds on the Broadcast Channel (BC) and also the cut-set bound. The proposed outer bound looks like the inner bound obtained by Kramer et. al for BRC.

In this paper, we introduce discrete memoryless Interference Channel (IFC) with two relays as two interfering transmitter-receiver pairs that are aided by two relays. We propose two different coding strategies for this channel. In the first strategy, we assume that each relay tries to mainly help one of the transmitter-receiver pairs through signal relaying and interference cancellation, while in the second strategy we assume that each relay tries to help both transmitter-receiver pairs. In our coding schemes, we employ rate-splitting, generalized block Markov coding, superposition coding and Gel'fand-Pinsker binning to cancel parts of the interference known to be experienced at the receivers. The derived achievable rate regions can be specialized to new achievable rate regions for discrete memoryless IFC with a relay. Under special conditions, the derived achievable rate regions also reduce to some previously known ones.transmitter-receiver pairs.

In this paper we consider a cognitive interference channel with two confidential messages. In our scenario, although the cognitive transmitter cooperates with the primary sender, the primary and cognitive messages must be secure at unintended receivers. The level of secrecy is measured by the equivocation rate. Also an expression is obtained for the rate-equivocation region of the discrete memoryless cognitive interference channel with confidential primary and secondary messages.

The Partially Cooperative Relay-Broadcast Channel (PC-RBC) is a generalization of Relay Channel in which the relay node decodes its own private message. In this paper, we introduce a class of parallel PC-RBCs with three unmatched subchannels, in which the first component of the channel is assumed to be degraded, the second to be orthogonal and the third to be deterministic. We characterize the capacity region of this channel for the case where the source sends a private message for each of the users. We also investigate a class of parallel relay channels with three unmatched subchannels, in which the first component of the channel is degraded, the second is orthogonal and the third is semi-deterministic, and characterize the capacity of it. Our capacity results enlarge the family of PC-RBCs and relay channels for which the capacity region is known.

In this paper, we consider Z Channel (ZC) with cooperation, where there are two senders and two receivers. The first sender transmits information to both receivers and also to the second sender. The first receiver and the second sender cooperate with the first sender in sending messages to the second receiver. The second sender transmits information only to its intended receiver. We first establish an achievable rate region for the general cooperative ZC. The coding scheme is based on rate splitting technique. At the receivers, we use joint decoding strategy. To illustrate the tightness of the proposed inner bound, we define degraded cooperative ZC. We derive an outer bound to the capacity region of the degraded cooperative ZC. It will be shown that the two bounds coincide and determine the capacity region of the degraded cooperative ZC.

A channel model for secret key generation between three terminals is considered. In this model, there is a two-user generalized multiple access channel (MAC) in which, in addition to the receiver, both transmitters receive noisy channel outputs. There is also a one-way public channel from the transmitters to the receiver. In this model, each of the transmitters intends to share a secret key with the receiver using the MAC and the public channel where the transmitters are eavesdroppers with respect to each other. In this setup, the channel outputs at the transmitters are only used for eavesdropping and not as inputs to the encoders. For the secret key rate pair, we derive the inner bound of the secret key capacity region. Thorough an example, it is shown that unlike the broadcast channel model, using a one-way public channel from the transmitters to the receiver is beneficial.

In this paper, we investigate optimal coding strategies for a class of linear deterministic relay networks. The network under study is a relay network, with one source, one destination, and two relay nodes. Additionally, there is a disturbing source of signals that causes interference with the information signals received by the relay nodes. Our model captures the effect of the interference of message signals and disturbing signals on a single relay network, or the interference of signals from multiple relay networks with each other in the linear deterministic framework. For several ranges of the network parameters we find upper bounds on the maximum achievable source-destination rate in the presense of the disturbing node and in each case we find an optimal coding scheme that achieves the upper bound.

We consider the Gaussian Dirty Tape Channel (DTC) Y = X + S + Z, where S is an additive Gaussian interference known causally to the transmitter. The general expression maxPU,f(·),X = f(U, S)I(U; Y) is proposed for the capacity of this channel. For linear assignment to f(-), i.e., X = U - βS, this expression leads to the compensation strategy proposed previously by Willems to obtain an achievable rate for the DTC. We show that linear assignment to f(·) is optimal under the condition that there exists a real number β* such that the pair (X + β S, U) is independent of the interference S. Furthermore, by applying a time-sharing technique to the achievable rate derived by linear assignment to f (·), an improved lower bound on the capacity of DTC is obtained. We also consider the Gaussian multiple access channel with additive interference, and study two different scenarios for this system. In the first case, both transmitters know interference causally while in the second, one transmitter has access to the interference noncausally and the other causally. Achievable rate regions for these two scenarios are then established.

In this paper, we investigate Causal Cognitive Interference Channel (CC-IFC) with delay in which the cognitive user transmission can depend on L future received symbols as well as the past ones. We study two special cases: CC-IFC without delay (L = 1), where the cognitive user can use only current and past received symbols, and CC-IFC with a block length delay (L = n), wherein the entire received sequence can be used. In each case, we obtain an inner bound on the capacity region. Our coding schemes are based on the generalized block Markov superposition coding and instantaneous relaying for CC-IFC without delay, and non-causal partial Decode-and-Forward (DF) for CC-IFC with a block length delay. Further, providing converse proofs, we show that the derived inner bounds are tight in some cases. Hence, we characterize the capacity regions for the classes of degraded and semi-deterministic CC-IFC without delay and CC-IFC with a block length delay, under strong interference conditions.

In this paper, we consider the two-user Z Channel (ZC). There are two senders and two receivers in the model. One of the senders transmits information to its intended receiver, while the other sender transmits information to both receivers. We establish a new achievable rate region for the ZC, using Marton's binning technique. At the receivers, we use joint decoding strategy. To illustrate the tightness of the proposed inner bound, we consider the degraded ZC which was first introduced by Chong et. al. We then characterize the capacity region of this type of degraded ZC.

The problem of secure communication over Multiple-Access Wiretap channel (MAC-WTC) under strong secrecy criterion is investigated. A new technique based on channel output statistics approximation is developed for establishing the strong security over multi-user channels. In particular, this technique shows that how simple wiretap coding results in secure communication under strong secrecy criterion instead of weak secrecy criterion. As a side result of the paper, two results on the output statistics of MAC are provided. Such results can be used to approximate the mutual information between input and output of MAC with respect to a given codebook of arbitrary rate.

The discrete memoryless state-dependent relay channel (SD-RC) is considered in this study. Two main cases are investigated: SD-RC with non-causal channel state information (CSI) and SD-RC with causal CSI. In each case, the SD-RC with partial CSI at the source and the relay is considered. As special cases it includes three different situations in which perfect CSI is available: (i) only at the source, (ii) only at the relay and (iii) both at the source and the relay. For the non-causal situation, the authors establish lower bound on capacity (achievable rate) of the SD-RC, using Gel'fand-Pinsker coding at the nodes informed of CSI and compress-and-forward (CF) strategy at the relay. Using the Shannon's strategy and CF relaying, the authors derive lower bound on capacity of SD-RC in the causal case. Furthermore, in order to compare their derived bounds with the previously obtained results, which are based on the decode-and-forward (DF) strategy, the authors consider general Gaussian relay channel (RC) with additive independent and identically distributed Gaussian state and noise, and obtain lower bounds on capacity for the cases in which perfect CSI is available non-causally at the source or at the relay. They also present cases in which their lower bounds outperform DF-based bounds, and can achieve rates close to the upper bound. For causal case, a numerical example of the binary fading Gaussian RC with additive noise is provided.

In this study, the authors extend the concept of relay channel with orthogonal components to define a class of symmetric relay networks with orthogonal components named symmetric orthogonal relay network. In the defined network, the channels diverge from each node sender use different frequency bands whereas the channels converge to each node receiver use the same frequency band. This structure is very well understood in half-duplex transmission systems where the relays cannot send and receive at the same time or over the same frequency band. The authors show that the unicast capacity of the defined network is equal to the cut-set bound. In the achievability proof, the authors take advantage of symmetric relaying and partial decode-and-forward strategies in which each relay in the network can partially decode the message transmitted by the other relays in addition to the source message.

The authors consider the problem of broadcast-relay-networks with two cooperative relays. There are a transmitter, two relays and two receivers in the network. The message of the transmitter intended to the receivers has common and private parts. The relays fully cooperate with each other and with the transmitter to send the common part of the message, whereas the private parts of the message are sent through the direct links between the transmitter and receivers. The authors found an achievable rate region for this network by using the symmetric relaying strategy. In this strategy, each relay completely decodes the message of other relay. In the proof the authors took advantage of regular encoding/sliding window decoding at relays and simultaneous backward decoding analysis at receivers. Marton's broadcast code construction is used at the transmitter to split the rate between the users. Three special cases of achievable rate region are shown: (i) Kramer's achievable rate region for broadcast relay channel; (ii) Ghabeli's achievable rate for symmetric two-relay network; and (iii) Marton's achievable rate region for broadcast channel with common message. The additive white Gaussian noise model is also considered and the achievable rate region of Gaussian network is discussed.

The authors introduce a generalisation of the multiple-access-relay-channel (MARC) called multiple-access-relay-network (MARN). The MARC model was first introduced by Kramer et al. and consists of many transmitters, one receiver and only one relay. In the MARN, there are many transmitters, many relays and one receiver. The authors obtained an achievable rate region for MARN by considering partial decode-and-forward (PDF) strategy at the relays. They showed that the region obtained using PDF strategy subsumes the region obtained by Kramer et al. for MARC. In the proposed coding scheme, the authors take advantage of PDF strategy based on regular encoding/backward decoding strategy. They also define semi-deterministic MARN, in which the output of the link between each transmitter and each relay is a deterministic function of the transmitter's input. The authors obtained an inner bound (using our achievable rate region) and also an outer bound on the capacity region of the semi-deterministic MARN and compared them.

New inner and outer bounds on the achievable compression–equivocation rate region for generalised secure data compression with side information are given that do not match in general. In this setup, two senders, Alice and Charlie intend to transmit information to Bob via channels with limited capacity so that he can reliably reconstruct their observations. The eavesdropper, Eve, has access to one of the channels at each instant and is interested in the source of the same channel at the time. Bob and Eve also have their own observations, which are correlated with Alice's and Charlie's observations. In this model, two equivocation and compression rates are defined with respect to the sources of Alice and Charlie. Furthermore, different special cases are discussed where the inner and outer bounds match. Our model covers the previously obtained results as well.

In this paper the Multiple Relay Channels (MRC) with delays, with and without channel state information (CSI) are investigated from an information theoretic point of view. For the MRC with unlimited look ahead where the relays can use the whole received block to encode, upper and lower bounds on the capacity are derived which are tight for the degraded case. For the MRC without-delay where the relays have access to the present received symbols in addition to the past symbols, the capacity of the degraded channel is established using Shannon's strategy for the channels with side information. Then we introduce the state dependent MRC with unlimited look ahead and derive a lower bound on the capacity when the CSI is noncausally available at the sender and relays, using Gel'fand-Pinsker coding technique. Finally, the capacity of the degraded Gaussian MRC with unlimited look ahead and with state noise (dirty paper problem) is established.

In this paper, we consider a discrete memoryless state-dependent relay channel with non-causal channel state information (CSI). We investigate three different cases in which perfect channel states can be known non-causally: (i) only to the source, (ii) only to the relay or (iii) both to the source and to the relay node. For these three cases we establish lower bounds on the channel capacity (achievable rates) based on using Gel'fand-Pinsker coding at the nodes where the CSI is available and using compress-and-forward (CF) strategy at the relay. Furthermore, for the general Gaussian relay channel with additive independent and identically distributed (i.i.d) states and noise, we obtain lower bounds on the capacity for the cases in which CSI is available at the source or at the relay. We also compare our derived bounds with the previously obtained results which were based on decode-and-forward (DF) strategy, and we show the cases in which our derived lower bounds outperform DF based bounds, and can achieve the rates close to the upper bound.

In this paper, we propose a new achievable rate for two-level relay networks by introducing a new strategy named simultaneous partial and backward decoding. In the proposed method, benefitting from regular encoding/backward decoding strategy, different message parts transmitted in the network are simultaneously decoded at the relays and the receiver. The proposed strategy is shown to achieve better rates than the previously proposed methods based on decode-and-forward and partial decode-and-forward.

In this paper, we consider partially and fully cooperative state-dependent relay broadcast channels with perfect causal channel state information (CSI). For these two channels, we study three different situations: 1) both the source and the relay nodes have access to perfect CSI, 2) perfect CSI is only known to the relay nodes, 3) perfect CSI is only available at the source node. In each situation we obtain the capacity region for a degraded version of the channel. Our work subsumes previously obtained results for the degraded broadcast and relay channels with perfect causal CSI.

We investigate the parallel partially cooperative relay broadcast channel with unmatched degraded subchannels. We characterize the capacity region of this channel in the general setting that, transmitter sends a common message for both users and a private message for each of them. Our achievability result is based on the choosing appropriate parameters for the general achievable rate region of partially cooperative relay broadcast channel. We provide a converse proof for this achievable region as well, which establishes the capacity region.

In this paper we prove a new capacity upper bound for a class of relay channels known as Relay-With-Delay channels. The proposed bound is general and holds for any arbitrary amount of delay. We have shown that the previously introduced bounds can be considered as special cases of our proposed upper bound. The new introduced bound is, in some cases, tighter than the previously established bounds. It is also notable that the proposed bound coincides with the previously known capacity of ¿Relay-With-Delay¿ channels.

In this paper, we consider reliable transmission of a discrete memoryless source over multi-relay networks with correlated Side Information (SI) available at the relay nodes and the final receiver. We obtain a necessary condition for reliable source transmission over a multi-terminal network with SI, which results in a necessary condition for a multi-relay network with SI, as a special case. We also propose a separate source-channel coding scheme, and based on it, a sufficient condition for a multi-relay network with SI is derived. Based on a partitioning method and the nature of a degraded relay network, we propose another coding scheme which results in a sufficient condition for a degraded relay network with SI. We show that these proposed schemes which are based on operational separation, achieve the same rates as the joint source-channel codes and these sufficient conditions are indeed necessary conditions for the degraded relay networks with degraded SI.

We present sufficient conditions for multicasting a set of correlated sources over cooperative networks. We propose a joint source-Wyner-Ziv encoding/sliding-window decoding scheme, in which each receiver considers an ordered partition of the other nodes. For each ordered partition, we obtain a set of feasibility constraints. We consolidate the results of the different ordered partitions by utilizing a result of geometrical approach to obtain the sufficient conditions. We observe that these sufficient conditions are indeed necessary conditions for Aref networks. As a consequence of the main result, we obtain an achievable rate region for networks with multicast demands. Also, we deduce an achievability result for two-way relay networks, where two nodes want to communicate over a relay network.

We define partial cognitive relay channel as a two-transmitter, two-receiver interference channel with a relay node such that one of the transmitters is a cognitive transmitter. As a more feasible assumption we assume that the cognitive transmitter has non-causally access to a part of the other transmitter's encoded message. The cognitive radio transmitter transmits simultaneously over the same channel instead of waiting for an idle channel which is traditional for a cognitive radio. We calculate the achievable rate region for partial cognitive relay channel based on the combination of partial decode-compress and forward for the relay, rate-splitting and Gel'fand and Pinsker coding. Numerical evaluation of the region in the practical Gaussian case is performed. We show that by defining a proper cooperation strategy among the transmitters, equipping some of them with the cognition capability and exploiting the relay nodes, the effective bandwidth of each transmitter will enhance greatly.

A secure channel coding (joint encryption-channel coding) scheme provides both data security and reliability in one combined process to achieve faster processing and/or more efficient implementation. The issue of using quasi-cyclic low-density parity-check (QC-LDPC) codes in a symmetric-key secure channel coding scheme is addressed. A set of this class of LDPC codes has recently been recommended by the NASA Goddard Space Flight Center for near-earth and deep-space communications. The proposed scheme provides an efficient error performance, an acceptable level of security and a low-complexity practicable implementation. The results indicate that the proposed scheme can efficiently employ large QC-LDPC codes to achieve a relatively smaller secret-key size to be exchanged by the sender and the receiver, and higher information rates in comparison with the previous symmetric-key McEliece-like schemes. Simulation results indicate that there is no trade-off between the error performance and the security level of the proposed scheme unlike that of the previous ones. These characteristics make the proposed scheme suitable for high-speed communications, such as satellite communication systems.

Symmetric relaying is a method of relaying in which the relays can decode the message of other relays in the network in addition to the source message. In this paper an achievable rate is presented for a symmetric two-relay network based on partial decoding. The strategy make use of familiar techniques such as product binning, regular encoding/sliding window decoding and regular encoding/backward decoding. The proposed rate is shown to subsume the previously proposed rate for feed-forward relay network based on decode-and-forward. This rate is also used to establish the capacity of a generalisation of Aref network called ‘semi-deterministic relay network with no interference at the relays’ and independent relay inputs.

Partial decoding scheme is a scheme in which each relay decodes only part of the transmitted message. Obviously, the achievable rates proposed by the partial decoding scheme subsume the achievable rates proposed by the full decoding scheme. The other motivation of using partial decoding scheme is that there are some special classes of relay networks such as semi-deterministic and orthogonal relay networks such that their capacities are obtained via this scheme. The authors propose a comprehensive partial decoding scheme based on regular encoding/sliding window decoding analysis to propose a new achievable rate for two-level relay networks. In contrast with the previously proposed methods, here the authors consider all possible partial decoding states that can occur between the different parts of the messages of the source and the relays in a two-level relay network. In this way, the common and private parts of the message transmitted by the source are defined to be decoded by the appropriate relays. Moreover, in the proof, the authors take advantage of regular encoding/sliding window decoding scheme that has superiorities to regular encoding/backward decoding and irregular encoding/random partitioning, in having less delay and yielding higher rates, respectively.

Gastpar and Vetterli named the ad hoc networks with one randomly selected source-destination pair as relay networks, and they suggested using arbitrary network coding in order to increase the overall efficiency. Here, the relay network is investigated with two relays, no interference and a new achievable rate is obtained using a new network coding (decode-and-broadcast). The obtained achievable rate (i) gives the lower bound for general relay channel, obtained by Cover and El Gamal, but with a slight difference owing to no interference assumption at the receiver, (ii) includes the one relay rates of a two-level relay channel studied by Gupta and Kumar using point-to-point coding, (iii) includes the rates of two-relay Aref network and other special two-relay networks, (iv) meets the max-flow min-cut upper bound under certain additional assumptions resulting in certain capacity theorems that include the related previous capacities, (v) is validated by its consistency with previous results relevant to special cases of broadcast channels.

The authors indicate the dependence between the inputs of the relay channel with one auxiliary random variable as Cover, El-Gamal and Salehi have done for the multiple access channel with arbitrarily correlated sources. Then, by considering broadcast and multiple access sub-channels in the relay channel, the authors describe the essential role of the relay with special Markovity conditions on the auxiliary random variable and channel input–outputs, and unify most of known capacity theorems into one capacity theorem. The capacity theorem potentially may be applicable to a more general class of relay channels including at least the relay channels with known capacity.

In recently proposed cipher algorithms, power functions over finite fields and specially inversion functions play an important role in the S-box design structure. In this study, a new systematic efficient method is introduced to cryptanalyse (to simplify and approximate) such S-boxes. This method is very simple and does not need any heuristic attempt and can be considered as a quick criterion to find some simple approximations. Using this new method, some approximations can be obtained for advanced encryption standard (AES) like S-boxes, such as AES, Camellia, Shark and so on. Finally as an application of this method, a simple linear approximation for AES S-box is presented.

An achievable rate region for the genie-aided cognitive radio channel is obtained using the celebrated Han-Kobayashi jointly decoding strategy for the interference channel and the Gel'fand-Pinsker coding scheme for channels with side information known at the transmitter. The achievable rate region is then simplified by Fourier-Motzkin elimination. The obtained achievable rate region (i) extends the Chong-Motani-Garg region for the interference channel to the cognitive channel and (ii) is a simplified description of the Devroye-Mitran-Tarokh rate region for the genie-aided cognitive radio channel.

In this paper, we propose a new concept of relaying named parallel relaying to obtain a new achievable rate for relay networks. The proposed encoding scheme is based on partial decoding, where the relay decodes only part of the transmitted message. The superiority of our proposed method to the previous ones is that, it can be applied to the relay networks with general structure, not necessarily with feed-forward structure. The proposed achievable rate is also used to establish the capacity of a class of semi-deterministic relay network which is a generalization of Aref network.

In this paper, we present a new generalization of the well- known Compress-and-Forward strategy for relay networks. We propose an offset decoding at destination, where destination considers an ordered partition of relays and decodes information of any partition with the help of information from prior partitions. We show that when we do not partition the set of relays, our result improves the result of Kramer, et al. A geometrical method is utilized to unify results of different ordered partitioning. Also, the unified result has a celebrated source-channel coding separation interpretation.

A specific class of differential cryptanalytic approach, named as impossible differential attack, has been successfully applied to several symmetric cryptographic primitives in particular encryption schemes such as Advanced Encryption Standard (AES). Such attacks exploit differences that are impossible at some intermediate state of the cipher algorithm. The best-known impossible differential attack against AES-128 has applied to six rounds. An attack on AES-128 up to seven rounds is proposed. The proposed attack requires 2115.5 chosen plaintexts and 2109 bytes of memory and performs 2119 seven-round AES encryptions. This is also the best-known attack on a reduced version of the AES-128 till now.

Polarity coincidence correlator (PCC), when used to estimate the covariance matrix on an element-by-element basis, may not yield a positive semi-definite (PSD) estimate. Devlin et al. (Devlin, 1975) claimed that element-wise PCC is not guaranteed to be PSD in dimensions p > 3 for real signals. However, no justification or proof was available on this issue. In this letter, it is proved that for real signals with p les 3 and for complex signals with p les 2, a PSD estimate is guaranteed. Counterexamples are presented for higher dimensions which yield invalid covariance estimates.

In this paper, we propose an information-theoretic constructive scheme based on generalized block Markov encoding strategy for obtaining an achievable rate for multirelay networks. The coding scheme is based on partial decoding scheme where the relay decodes only part of the transmitted message. The proposed achievable rate is then used to establish the capacity of a class of semi-deterministic relay networks composed of semi- deterministic relay channels. It is shown that the proposed rate will include those of previously proposed rates based on decode- and-forward strategy in some special cases.

We propose computationally inexpensive and efficient solutions for signal activity detection of phase-shift keying (PSK) signals in additive white Gaussian noise. We consider the complex amplitude of the signal as well as the information sequence as the unknown parameters. In addition, the noise variance is assumed unknown. We derive the generalized likelihood ratio test (GLRT) and suggest a computationally efficient implementation thereof. Furthermore, we develop a new inexpensive detector for binary PSK signals, which we will refer to as the generalized energy detector. To evaluate the performance of these detectors, we attempt to derive a uniformly most powerful invariant test (UMPI) as an optimal detector. It turns out that the UMPI test exists only if the signal-to-noise ratio is known. We use this UMPI test in order to obtain an upper-bound performance for the evaluation of invariant detectors, such as the above-mentioned GLRT. Simulation results illustrate and compare the performance and the efficiency of the proposed signal activity detectors.

We propose computationally inexpensive and efficient solutions for signal activity detection of phase-shift keying (PSK) signals in additive white Gaussian noise. We consider the complex amplitude of the signal, as well as the information sequence, as the unknown parameters. In addition, the noise variance is assumed unknown. We derive the generalized likelihood ratio test (GLRT) and suggest a computationally efficient implementation thereof. Furthermore, we develop a new inexpensive detector for binary PSK signals, which we will refer to as the generalized energy detector. To evaluate the performance of these detectors, we attempt to derive a uniformly most powerful invariant (UMPI) test as an optimal detector. It turns out that the UMPI test exists only if the signal-to-noise ratio is known. We use this UMPI test in order to obtain an upper-bound performance for the evaluation of invariant detectors, such as the GLRT. Simulation results illustrate and compare the performance and the efficiency of the proposed signal activity detectors

In this paper, we focus on the reverse link traffic analysis of a code-division multiple-access (CDMA) cellular network in dynamic environments. In this respect, we propose a new and flexible traffic model, which takes into account the interference-limitedness attribute of CDMA capacity as well as its soft-handoff feature. This new traffic model is developed according to an interference-based call admission control (ICAC) method and a geographical structure with three regions. The main advantage of this traffic model is in its flexibility when we consider different traffic conditions including time-varying status of traffic in the neighboring cells.

In this paper, we propose a general mobility model suitable for wireless multimedia networks. Our model is based on splitting a region into subregions. Furthermore, we make an analogy between subregions as well as their inter-connections with a multi-class Jackson queueing network comprising of infinite-server nodes. The main attribute of such a network is due to its product-form stationary distribution. Using this model, we are able to obtain a closed analytical form for the spatial traffic distribution corresponding to a specific number of network-connected users with different classes of service and mobility in a typical region. Also, we show the flexibility obtained by the proposed mobility model in representing some general distributions such as sum-of-hyper-exponentials (SOHYP), hyper-Erlang and Cox which were previously suggested to model mobility-related statistical parameters, e.g., cell dwell time and channel holding time. Finally, we apply the proposed model to a few mobility scenarios and obtain the resultant active user's location density.

One of the most prominent features of code division multiple-access (CDMA) cellular networks is their ability for applying soft-handoff. This type of handoff results in a better support of seamless communication services, capacity enhancement, QoS improvement, etc. Because of the existence of more parameters and flexibilities compared to hard-handoff, an optimum solution for soft-handoff management and admission control for new and handoff calls is necessary. We propose a new algorithm with two thresholds for admission of new and handoff calls, and with two decision boundaries for controlling of handoff traffic. We compare this algorithm with a simpler one with only one decision boundary, by employing a general and flexible 3-dimensional framework with respect to important traffic parameters including loss probability, carried traffic, blocking and dropping probabilities, and show that our algorithm can result in less loss probability as well as less blocking and dropping probabilities with more control over traffic growth in the cell.

The capacity of the class of relay channels with senderx_{1}, a relay senderx_{2}, a relay receivery_{1}=f(x_{1},x_{2}), and ultimate receiveryis proved to beC = \max\min_{p(x_{1},x_{2})} \{I(X_{1}, X_{2}; Y), H(Y_{1}|X_{2})+I(X_{1};Y|X_{2},Y_{1}})\}.