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This article uses theories of industrial policy to assess the development of China's 5G telecommunications equipment policy. It considers the path China's 5G build-out has taken, and American security concerns in reaction to several nations' potential adoption of China's latest generation of communications equipment. It focuses on several East, South, and Southeast Asian countries and their decisions on whether or not to incorporate China's 5G technology for their networks. It concludes with assessment of future paths in the Sino-US competition over 5G and later generation communications systems adoption. [ABSTRACT FROM AUTHOR]

In the process of group decision-making, different decision-makers have different risk attitudes. There are quantum entanglements among the opinions of decision-makers, influencing each other rather than being independent of each other. To address this issue, a multi-attribute quantum group decision-making method considering decision-maker's risk attitude is developed. First, considering the uncertain environment of decision-making, the interval-valued intuitionistic fuzzy number is used to represent the decision information, and a new scoring function is proposed to transform the interval intuitionistic fuzzy matrix into a scoring function matrix. Second, the interference entanglement behavior of the decision-maker in the decision-making process is deduced by quantum probability, and the quantum probability is transformed into the weight of the attributes. Then, the prospect value function is determined according to the expectation reference point of different decision-makers, and the irrational risk attitude of decision-makers is reflected by comprehensive prospect value, which is used to rank the alternatives. Finally, a case of global telecommunication system security assessment is provided to verify the feasibility, effectiveness, and superiority of the proposed method. [ABSTRACT FROM AUTHOR]

Undoubtedly, Industry 4.0 in the energy sector improves the conditions for automation, generation and distribution of energy, increasing the rate of electric vehicle manufacturing in recent years. As a result, more grid-connected charging infrastructures are being installed, whose charging stations (CSs) can follow standardized architectures, such as the one proposed by the open charge point protocol (OCPP). The most recent version of this protocol is v.2.0.1, which includes new security measures at device and communication level to cover those security issues identified in previous versions. Therefore, this paper analyzes OCPP-v2.0.1 to determine whether the new functions may still be susceptible to specific cyber and physical threats, and especially when CSs may be connected to microgrids. To formalize the study, we first adapted the well-known threat analysis methodology, STRIDE, to identify and classify threats in terms of control and energy, and subsequently we combine it with DREAD for risk assessment. The analyses indicate that, although OCPP-v2.0.1 has evolved, potential security risks still remain, requiring greater protection in the future. [ABSTRACT FROM AUTHOR]

Speaker recognition is one of several biometric recognition systems owing to its high importance in numerous applications of security and telecommunications. The key aspiration of speaker recognition systems is to know who is speaking depending on voice characteristics. This paper presents an extensive study of speaker recognition in both text-dependent and text-independent cases. Convolutional Neural Network (CNN) based feature extraction is extended to the text-dependent and text-independent speaker recognition tasks. In addition, the effect of reverberation on the speaker recognition system is addressed. All speech signals are converted into images by obtaining their spectrograms. Two proposed CNN models are presented for efficient speaker recognition from clean and reverberant speech signals. They depend on image processing concepts applied on spectrograms of speech signals. One of the proposed models is compared with a conventional Benchmark model in the text-independent scenario. The performance of the recognition system is measured by the recognition rate in the cases of clean and reverberant speech. [ABSTRACT FROM AUTHOR]

Cybersecurity has become a major concern in the modern world. A serious threat to wireless networks is eavesdropping. On the other hand, usable spectrum is diminishing due to the presence of various wireless services. To address the problem, highly spectral efficient methods have been introduced e.g. spectrum sharing. Cognitive radio networks could sense unused spectrum and make use of it. In this paper, the cognitive radio is to perform a second task, i.e. jamming the eavesdropper. This paper is significant in revealing the cognitive radio's energy efficiency in this setting, where a cognitive transmitter (CT) can transmit its own data when it senses the absence of primary transmitter (PT). If PT is present, CT is to jam an eavesdropper (EA) by transmitting artificial noise. Our main contribution is finding the CT's optimal energy efficiency. Through the proposed formulas, we have determined the fractions of time and power required by CT to achieve the optimal energy efficiency, subject to constraints like minimum required secrecy rate Rs, etc. Our major findings are: (1) only a small portion of a time frame (66 μs in our setting) is required for sensing. CT can utilize the remaining time for sending its data or jamming EA. (2) To achieve a target energy efficiency of 0.5 bps/Hz/J, PT should not be actively transmitting more than 35% of the time, and Rs should not be larger than 1.2 bps/Hz. [ABSTRACT FROM AUTHOR]

Steganography is an important branch of information hiding, which is an effective way to solve the problem of communication security. Steganography can hide specific secret information in some kind of public information, such as images, documents, audio and video, without any suspicion. Joint Photographic Experts Group (JPEG) compressed image is the most widely used image format on the Internet. Recently, a series of JPEG image steganographic algorithms have been proposed. However, the existing JPEG steganography usually designs the cost function based on the statistical distribution in the DCT domain. In this paper, with the help of a "Microscope", which can enhance the JPEG images in the spatial domain and highlight the texture regions, we design the steganographic cost function based on the statistical distribution of JPEG images in spatial domain and work out a JPEG image steganography with high security performance. Experimental results demonstrate that the proposed designing strategy is a practical approach to against several existing state-of-the-art steganalytic tools. [ABSTRACT FROM AUTHOR]

In the digital world, watermarking technology is a solution for data hiding and completely essential for management and secure communications of digital data propagated over the internet-based platforms. Reversible watermarking is a quality-aware type of watermarking which has been applied in managing digital contents such as digital images, texts, audios and videos. Reversible watermarking is also known as lossless watermarking due to its preservation of all details of host and hidden data. One of the important uses of this kind of watermarking is to manage medical data regarding DICOM images. In the recent years, a new type of reversible watermarking technology entitled interpolation-based reversible watermarking has been introduced, and we are going to enhance it for DICOM images by using a hybrid approach based on computing error histogram and by applying an image interpolation with greedy weights (adaptive weighting). In practice, simulation results clearly show better performance of the proposed scheme compared to the previous techniques using interpolation-based reversible watermarking on different DICOM images. [ABSTRACT FROM AUTHOR]

Device-to-Device (D2D) communications have emerged as a promising technology for the next generation mobile communication networks and wireless systems (5G). As an underlay network of conventional cellular networks (LTE or LTE-Advanced), D2D communications have shown great potential in improving communication capability and fostering multifarious new applications and services. However, new application scenarios and system architecture expose establishment of D2D communications into unique security threats. Therefore, it is necessary to take security requirements into the design of D2D communications in order to ensure security and correct operations of the network. In this paper, we proposed a Universal Authentication and Key Agreement protocol for D2D communications (UAKA-D2D) to achieve secure communication session establishment, where user roaming and inter-operator operation are considered. Our protocol adopts Diffie-Hellman Key Exchange algorithm (DHKE) to achieve privacy preserving session key generation and employs message authentication code to achieve mutual authentication between D2D users. The security of the proposed protocol is analyzed theoretically and verified by a formal security verification tool. Finally, we evaluated the performance of the protocol in terms of computation and communication costs based on extensive analysis and simulations. The results show the efficiency and practicality of the proposed protocol. [ABSTRACT FROM AUTHOR]

Physical layer security has emerged as a promising approach to strengthen security of wireless communications. Particularly, extracting secret keys from channel randomness has attracted an increasing interest from both academic and industrial research groups. In this paper, we present a complete implantation of a secret key generation (SKG) protocol which is compliant with existing widespread Radio Access Technologies. This protocol performs the quantization of the channel state information, then information reconciliation and privacy amplification. We also propose an innovative algorithm to reduce the correlation between quantized channel coefficients that significantly improves the reliability and the resilience of the complete SKG scheme. Finally we assess the performance of our protocol by evaluating the quality of secret keys generated in various propagation environments from real single sense LTE signals, and real single and dual sense WiFi signals. [ABSTRACT FROM AUTHOR]

In this paper we present a new scheme combining artificial noise beam forming and secrecy coding to strengthen the security of existing wireless communication systems. Artificial noise and beam forming guarantee a radio advantage to legitimate users, enabling the use of our secrecy coding scheme to provide reliability and secrecy. This overall security protocol is compliant with existing widespread radio access technologies and it can be considered as a key-free add-on to improve security of the physical layer of wireless networks. [ABSTRACT FROM AUTHOR]

The integrated design for both radar and anonymous communication has drawn more attention recently since wireless communication system appeals to enhance security and reliability. Given the frequency hopping (FH) communication system, an effective way to realize integrated design is to meet the spectrum compatibility between these two systems. The paper deals with a unimodular sequence design technique which considers optimizing both the spectrum compatibility and peak sidelobes levels (PSL) of auto-correlation function (ACF). The spectrum compatibility requirement realizes anonymous communication for the FH system and provides this system lower probability of intercept (LPI) since the spectrum of the FH system is hidden in that of the radar system. The proposed algorithm, named generalized fitting template (GFT) technique, converts the sequence optimization design problem to a iterative fitting process. In this process, the power spectrum density (PSD) and PSL behaviors of the generated sequences fit both PSD and PSL templates progressively. Two templates are established based on the spectrum compatibility requirement and the expected PSL. As noted, in order to ensure the communication security and reliability, spectrum compatibility requirement is given a higher priority to achieve in the GFT algorithm. This algorithm realizes this point by adjusting the weight adaptively between these two terms during the iteration process. The simulation results are analyzed in terms of bit error rate (BER), PSD, PSL, and signal-interference rate (SIR) for both the radar and FH systems. The performance of GFT is compared with SCAN, CAN, FRE, CYC, and MAT algorithms in the above aspects, which shows its good effectiveness. [ABSTRACT FROM AUTHOR]

Recently, Wang et al. (J Secur Commun Netw 5(12):1363-1374, 2012) proposed a self-healing group key distribution (SGKD) scheme for resource-constrained wireless networks. They claimed that their proposed SGKD scheme satisfies forward security, backward security and can resist collusion attack. Unfortunately, we found some security flaws in their scheme. In this paper, we present a method to attack this scheme. The attack illustrates that this scheme does not satisfy forward security, which also directly breaks the collusion resistance capability. We also propose an improved scheme with constant storage overhead and satisfactory security. [ABSTRACT FROM AUTHOR]

The reliability of peers is very important for safe communication in peer-to-peer (P2P) systems. The reliability of a peer can be evaluated based on the reputation and interactions with other peers to provide different services. However, for deciding the peer reliability there are needed many parameters, which make the problem NP-hard. In this paper, we present two fuzzy-based systems (called FBRS1 and FBRS2) to improve the reliability of JXTA-overlay P2P platform. In FBRS1, we considered three input parameters: number of interactions (NI), security (S), packet loss (PL) to decide the peer reliability (PR). In FBRS2, we considered four input parameters: NI, S, PL and local score to decide the PR. We compare the proposed systems by computer simulations. Comparing the complexity of FBRS1 and FBRS2, the FBRS2 is more complex than FBRS1. However, it also considers the local score, which makes it more reliable than FBRS1. [ABSTRACT FROM AUTHOR]

We propose a four-state quantum key distribution (QKD) scheme using generalized measurement of nonorthogonal states, the maximum mutual information measurement strategy. Then, we analyze the eavesdropping process in intercept-resend and photon number splitting attack scenes. Our analysis shows that in the intercept-resend and photon number splitting attack eavesdropping scenes, our scheme is more secure than BB84 protocol and has higher key generation rate which may be applied to high-density QKD. [ABSTRACT FROM AUTHOR]

Forward-secure signatures are proposed to diminish the damage of key exposure, in which the security of signatures prior to the period of key exposure can be kept. Identity-based signatures can reduce the complexity and the cost for managing the public key because the public key is replaced by any known information of a user's identity. In this paper, we discuss a new issue related to integrating forward-secure and identity-based primitives into standard applications of personal network communication security such as pretty good privacy suite and secure/multipurpose internet mail extensions in which the secret key is additionally protected by an extra secret that is possibly derived from a password. One major contribution of this paper is to construct the first forward-secure identity-based signature scheme in untrusted update environments. In this scheme, the public key can be derived from some arbitrary identification value such as an email address or a phone number, and the signing key is additionally shielded by a second factor derived from a user's password. Key update can be completed by the encrypted version of signing keys. The second factor is only needed when the signatures are produced. In addition, we give the definitions of forward security and update security in this kind of signature. At last, formal proofs of forward security and update security in the random oracle model are provided under the CDH assumption. [ABSTRACT FROM AUTHOR]

In this paper, we focus on the non-existence of isolated nodes in secure wireless sensor networks under full visibility condition. Here, we consider a sensor network with n sensor nodes distributed uniformly over a compact space $$C \subset {\mathbb {R}}^2$$ . We establish a threshold for the proportion of key ring and key pool size; above this threshold isolated nodes disappear from the network almost surely. We derive that for key pool of size $$cn\log \,n$$ and key ring of size $$c\log \,n$$ (of an arbitrary node) and $$c>2$$ there will be no isolated nodes in the network almost surely. [ABSTRACT FROM AUTHOR]

The remote health monitoring system enables a doctor to diagnose and monitor health problems anywhere for a patient. However, since the patient health information is very sensitive and the Internet is unsecure and prone to many attacks, data can be easily compromised by adversaries. Worse, the mobile phone is also easy to be compromised. Clearly, these issues have brought different privacy and security requirements in wireless healthcare. To address these challenging issues, in this paper, we propose an efficient privacy-preserving authentication scheme with adaptive key evolution, which can prevent illegal access to the patient's vital signs. Furthermore, we model the leakage process of the key information to set proper key renewal interval, which can adaptively control the key evolution to balance the trade-off between the communication efficiency and security level. The security analysis demonstrates that our scheme can achieve authenticated key agreement, perfect and strong key insulation, privacy preservation, and other important security goals, e.g. authenticity, integrity and freshness of transmitted messages. The performance evaluation shows that our scheme is computationally efficient for the typical mobile phone with limited resources, and it has low communication overhead. [ABSTRACT FROM AUTHOR]

Secure protocol is a vital guarantee in all kinds of communication network environment. Designing on authenticated key exchange protocols is a hotspot in the field of information security at present, and the related theories have been increasingly mature. However, there is still scarcely any appropriate security protocol to guarantee the communication security of wireless body area networks (WBANs). In this paper, according to the standards on WBAN, we define a layered network model in accordance with the definition of two-hop star network topology firstly. In line with this model, we put forward two new authenticated key exchange protocols based on symmetric cryptosystem, which are suitable for WBAN application scenario. The proposed protocols support the selective authentication between nodes in WBAN. Simultaneously, two pairs of session key are generated efficiently and succinctly in each certification process. Finally, after security analyzing and performance evaluating demonstrate that the proposed key agreement protocols are proved to meet desired security properties with light computation and communication overhead. The proposed protocols provide a primitive to develop efficient and secure WBAN systems. [ABSTRACT FROM AUTHOR]

In this paper, synchronization of fuzzy modeling chaotic time delay memristor-based Chua's circuits is presented. Based on T-S fuzzy models, not only fuzzy model of the time delay memristor-based Chua' circuit is constructed but the fuzzy control vector can also be derived to synchronize two different time delay memristor-based Chua's circuits. Due to the dynamical behavior with complex transient transitions of the memristor-based chaotic system which is heavily dependent on the initial state of the memristor except for the circuit parameters, the memristor-based chaotic system can generate more complex and unpredictable time domain signals. An application to chaos secure communication is used to demonstrate the effectiveness of the proposed chaotic synchronization scheme. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the availability of 1-for- 2 shared protection systems. We assume that there are 2 working units each serving a single user and one shared protection (spare) unit in the system. We also assume that the time to failure is subject to an exponential distribution and that the time to repair is subject to a general distribution. Under these assumptions, we derive the availability for each user by combining the state transition analysis and the supplementary variable method. We also show the effect of the repair time distribution, the failure rates and the repair rates of the units through the case study of small-sized 2 enterprises that share one spare device for backup. [ABSTRACT FROM AUTHOR]

The Goldenberg-Vaidman (GV) protocol for quantum key distribution uses orthogonal encoding states of a particle. Its security arises because operations accessible to Eve are insufficient to distinguish the two states encoding the secret bit. We propose a two-particle cryptographic protocol for quantum secure direct communication, wherein orthogonal states encode the secret, and security arises from restricting Eve from accessing any two-particle operations. However, there is a non-trivial difference between the two cases. While the encoding states are perfectly indistinguishable in GV, they are partially distinguishable in the bipartite case, leading to a qualitatively different kind of information-versus-disturbance trade-off and also options for Eve in the two cases. [ABSTRACT FROM AUTHOR]

With the advent of new generation of mobile access devices such as smartphone and tablet PC, there is coming a need for ubiquitous collaboration which allows people to access information systems with their disparate access devices and to communicate with others in anytime and in anywhere. As the number of collaborators with a large number of disparate access devices increases in ubiquitous collaboration environment, the difficulties for protecting secured resources from unauthorized users as well as unsecured access devices will increase since the resources can be compromised by inadequately secured human and devices. Therfore, authentication mechanism for access of legitimate participants is essential in ubiquitous collaboration environment. In this paper we present an efficient authentication mechanism in ubiquitous collaboration environment. We show that proposed scheme is secure through security analysis and is efficient through the experimental results obtained from the practical evaluation of the scheme in ubiquitous collaboration environment. [ABSTRACT FROM AUTHOR]

When the grays of images present a strong contrast, merely encrypting the gray-level of image pixels is unable to eliminate the image outlines. The adoption of pixel shuffling can eliminate the image outlines, but cannot disrupt the characteristics of gray-level spectrum. Since a chaotic system is highly sensitive to the initial values and the chaotic trajectory is unpredictable, the application of this method to communication encryption and decryption renders a high level of security. In this paper, the chaotic system is adopted as the fundamental base and combined with row, column shuffling, and gray-level encryption to not only eliminate image outlines, but also disrupt the distributional characteristics of gray level, and the resulting increases of key space. Various statistical methods, such as correlation coefficient, NPCR (Number of Pixels Change Rate), UACI (Unified Average Changing Intensity), and entropy, provide analysis of the efficacy of the encryption method proposed. Our example reveals that the proposed encryption method can obtain highly secure encrypted images. [ABSTRACT FROM AUTHOR]

With computer networks spreading into a variety of new environments, the need to authenticate and secure communication grows. Many of these new environments have particular requirements on the applicable cryptographic primitives. For instance, a frequent requirement is that the communication overhead inflicted be small and that many messages be processable at the same time. In this paper, we consider the suitability of public key signatures in the latter scenario. That is, we consider (1) signatures that are short and (2) cases where many signatures from (possibly) different signers on (possibly) different messages can be verified quickly. Prior work focused almost exclusively on batching signatures from the same signer. We propose the first batch verifier for messages from many (certified) signers without random oracles and with a verification time where the dominant operation is independent of the number of signatures to verify. We further propose a new signature scheme with very short signatures, for which batch verification for many signers is also highly efficient. Combining our new signatures with the best known techniques for batching certificates from the same authority, we get a fast batch verifier for certificates and messages combined. Although our new signature scheme has some restrictions, it is very efficient and still practical for some communication applications. [ABSTRACT FROM AUTHOR]

We present a high-capacity quantum secure direct communication (QSDC) protocol with single photons in both the polarization and the spatial-mode degrees of freedom. With a single photon traveling forth and back from the receiver to the sender, it can carry 2 bits of information as the sender can encode his message on both the polarization states and the spatial-mode states of single photons independently. Moreover, our QSDC protocol is feasible as the preparation and the measurement of a single-photon quantum state in both the polarization and the spatial-mode degrees of freedom is not difficult with current technology. [ABSTRACT FROM AUTHOR]

A controlled quantum secure direct communication protocol (Zhang et al. in Int. J. Theor. Phys. 48:2971-2976, ) by using four particle cluster states was proposed recently. Yang et al. presented an attack with fake entangled particles (FEP attack) and gave an improvement (Yang et al. in Int. J. Theor. Phys. 50:395-400, ). In this paper, we reexamine the protocol's security and discover that, Bob can also take a different attack, disentanglement attack, to obtain Alice's secret message without controller's permission. Moreover, our attack strategy also works for Yang's improvement. [ABSTRACT FROM AUTHOR]

In this paper, we have discussed the application of new nonlinear recursive controllers on Josephson junction (JJ) chaotic systems. Controlling bifurcation as well as chaos has been rapidly advancing in the last decade. Thus, emphasis has been placed on control design techniques which result in prescribed nonlinear performance dynamics for practical controlled processes. This study has shown that a nonlinear recursive controller is effective in controlling an undesirable JJ chaotic behavior. In addition to that, the synchronization of two JJ chaotic nonlinear dynamical systems can be used to advantage in communication systems. In fact, communication security is promising through chaos. Using nonlinear control method, we have demonstrated that it is possible to achieve synchronization in electronic circuits such as JJ. The study showed the effectiveness of the designed controller in communication signal synchronization. For the purpose of verification and comparison, we designed a control signal based on master and slave concept. [ABSTRACT FROM AUTHOR]

We propose a new one-time proxy signature scheme with decoherence-free states. We analyze its security and show that it is not possible to forge a valid proxy signature even if an opponent has infinite resources. Furthermore, the differences between this scheme and others are discussed. [ABSTRACT FROM AUTHOR]

A quantum key distribution protocol with information coding by the time of photon arrival based on four linearly dependent single-photon states is proposed and the resistance of the protocol to a realistic intercept-resend attack is analyzed. The protocol on four linearly independent states is shown to be sensitive to an attack with unambiguous discrimination of all states when the level of losses in the quantum channel is higher than 7.2 dB. [ABSTRACT FROM AUTHOR]

We address the effect of classical correlations, introduced to a quantum resource used for the continuous-variable quantum key distribution. The set-up is based on an entangled source with two trusted parties performing homodyne measurements on their modes, thus corresponding to the preparation of squeezed states, while one of the modes is traveling to the remote party through lossy and noisy channel. The security of the scheme is considered against individual and collective eavesdropping attacks. It is shown that the classical correlations added to the entangled source increase the performance of the scheme both quantatively in terms of the secure key rate and qualitatively in terms of the security region with respect to the tolerable excess noise for both types of attacks and the improvement is essentially significant for sources possessing low degree of nonclassicality. [ABSTRACT FROM AUTHOR]

Enforcing security often requires the two legitimate parties of a communication to determine if they share a secret, without disclosing information (e.g., the shared secret itself, or just the existence of such a secret) to third parties. In this paper, we propose CASSANDRA, a toolbox composed of three probabilistic protocols that allows two parties, each one having a subset of elements drawn by a pre-determined set, to compute information about the intersection of such two sets. In particular, C-void decides whether the two sets are disjoint; C-size allows to compute how many elements the intersection is composed of; and, C-set returns the identity of the elements of the intersection (if any). These protocols differ, other than in functionality, also in the degree of assurance they can provide and the degree of interactions required by the two parties. The communication cost also differs, but in any case, it is below the cost of competing solution representing the state of the art. These protocols also share some common features: that is, they are completely tunable and specifically suited for devices having constraints on energy, communication, storage, and bandwidth. Examples of these devices are portable devices (e.g., phones) handling satellite communications, or nodes of wireless sensor networks. Thorough analysis and extensive simulations support our findings. [ABSTRACT FROM AUTHOR]

This paper focuses on the security and privacy threats being faced by the low-cost RFID communication system, the most challenging of which relate to eavesdropping, impersonation, and tag cloning problems. The security issues can be improved and solved by utilizing both prevention and detection strategies. Prevention technique is needed since it offers resistance capabilities toward eavesdroppers and impersonators. Detection technique is vital to minimize the negative effects of tag cloning threats. This paper proposes the use of both prevention and detection techniques to make RFID communication more secure. Lightweight cryptographic algorithm, which conforms to the EPC Class-1 Generation-2 standard, is used in the proposed mutual authentication protocol for RFID system to raise security levels. In addition, electronic fingerprinting system is deployed in the proposed solution as a detection method to distinguish counterfeit and legitimate tags. [ABSTRACT FROM AUTHOR]

Key management is one of the important issues in ensuring the security of network services. The aim of key management is to ensure availability of the keys at both the receiver’s and the sender’s ends. Key management involves two aspects: key distribution and key revocation. Key distribution involves the distribution of keys to various nodes with secrecy to provide authenticity and privacy. Key revocation involves securely and efficiently managing the information about the keys which have been compromised. This paper presents the geographic server distributed model for key revocation which concerns about the security and performance of the system. The concept presented in this paper is more reliable, faster and scalable than the existing Public Key Infrastructure (PKI) framework in various countries, as it provides optimization of key authentication in a network. It proposes auto-seeking of a geographically distributed certifying authority’s key revocation server, which holds the revocation lists by the client, based on the best service availability. The network is divided itself into the strongest availability zones (SAZ), which automatically allows the new receiver to update the address of the authentication server and replace the old address with the new address of the SAZ, in case it moves to another location in the zone, or in case the server becomes unavailable in the same zone. In this way, it reduces the time to gain information about the revocation list and ensures availability and, thus, improvement of the system as a whole. Hence, the proposed system results in scalable, reliable and faster PKI infrastructure and will be attractive for the users who frequently change their location in the network. Our scheme eases out the revocation mechanism and enables key revocation in the legacy systems. It discusses the architecture as well as the performance of our scheme as compared to the existing scheme. However, our scheme does not call for the entire change in PKI, but is compatible with the existing scheme. Our simulations show that the proposed scheme is better for key revocation. [ABSTRACT FROM AUTHOR]

Channels encrypting quantum bits by the application of randomly chosen unitary operators are studied. Quantities based on averages of linear entropies which characterize certain aspects of the encoding quality and the non-malleability of the channels are introduced. The relation between the entropy of the classical key and the choice of the encryption operators with the behaviour of these properties is discussed. The extension of exact private quantum channels in order to improve non-malleability via additional encryption operators is considered. [ABSTRACT FROM AUTHOR]

In this paper, a systematic approach and their corresponding metrics for concurrent anti-jamming (AJ) and low probability of detection (LPD) performance evaluations of a secure communications system are investigated. In general, it is necessary to deal simultaneously with adversary threats of both active jamming and passive detection for a secure communications system concern. For independent or concurrent AJ and LPD performance evaluations, a single varying paired and multiple paired fixed collocated jammers/interceptors scenario is explored with real sinc type ( sin( x)/ x) antenna patterns being considered for the communicators. The error probability with both AJ and LPD being considered simultaneously can be derived as system- and geometry-dependent factors and categorized as system metrics related to jammers, interceptors, and communicators themselves only. Whenever multiple collocated jammers/interceptors are considered, we can observe interesting “smoothed” effects for bit energy to jamming density ratio ( E b/ J o), when one of these varying jammers/interceptors is approaching or receding. In addition, by means of these system metrics, it is intuitive and straightforward to enhance system performance for the victim or to deteriorate system performance for the adversary, respectively. Moreover, the proposed approach and metrics have also paved one practical way for the developments of the latest emphasized cognitive radio (CR) communications systems, if all the collocated jammers/interceptors on the proposed scenario are replaced with “cooperative” communicators. [ABSTRACT FROM AUTHOR]

The network addresses of principals in a mobile ad hoc network (MANET) are conventionally assumed to be public information. This may cause devastating consequences for MANETs deployed in hostile environments. For example, attackers can easily locate a target principal based his known network address and then launch a pinpoint attack. This paper identifies address privacy as a new security requirement to prevent attackers from ascertaining network addresses of MANET principals. We further present Swarms, the first solution to satisfying this requirement. Swarms eliminates the conventionally explicit one-on-one mappings between MANET principals and network addresses and allows any two principals to communicate while blind to each other’s address. We quantitatively measure the address privacy offered by Swarms via an entropy-based information-theoretic metric. [ABSTRACT FROM AUTHOR]

In this paper, experimental realisation of synchronisation of strange nonchaotic attractor in unidirectionally coupled Wien-bridge oscillator is presented. Preliminary work of chaotic and strange nonchaotic dynamics with diode as the nonlinear element is published in J. Nonlinear Dyn. 2015, 1 (2015). In this work, two Wien-bridge oscillators are coupled at the aperiodic dynamics for application in secure communication. The dynamics of the coupled system is explored by experimental and numerical studies. Employing the simple communication masking method with aperiodic dynamics offers some advantages rather than using chaotic attractors, i.e., the range of control parameter value is smaller than the range for which the system exhibits chaotic behaviour. The performance of the system is evaluated and it is found that experimental result agrees with numerical results. [ABSTRACT FROM AUTHOR]