Abstract

We have analysed the effect of beam wander, jitter and boresight on the deviation of centroid of laser beam. It is seen to be wandering over a restricted range, though off the center of detector.

Abstract

Research has proven that accomplishing security properties while improving performance of an authentication protocol is a challenging task. Numerous authentication protocols proposed in the recent times are still behind in achieving the concrete objectives. Qi et al. and Lu et al. recently proposed two-factor authenticated key-agreement protocols for client–server architecture. This paper revisits their protocols and analyzes the shortcomings of such approaches. We also propose an improved authenticated key agreement protocol for client–server environment to defeat mentioned weaknesses of existing protocols that are discussed in related works. The rigorous security analysis using Burrows–Abadi–Needham logic, formal security verification using Real-OR-Random model, simulations using the Automated Validation of Internet Security Protocols and Applications tool, and the informal security analysis shows that the proposed protocol is secure. Additionally, we summarize the results to ensure that the proposed protocol is efficient compared to the existing related protocols.

Abstract

Authentication schemes are widely used mechanisms to thwart unauthorized access of resources over insecure networks.Several smart card based password authentication schemes have been proposed in the literature. In this paper, we demonstrate the security limitations of a recently proposed password based authentication scheme, and show that their scheme is still vulnerable to forgery and offline password guessing attacks and it is also unable to provide user anonymity, forward secrecy and mutual authentication. With the intention of fixing the weaknesses of that scheme, we present a secure authentication scheme. We show that the proposed scheme is invulnerable to various attacks together with attacks observed in the analyzed scheme through both rigorous formal and informal security analysis. Furthermore, the security analysis using the widely-accepted Real-Or-Random (ROR) model ensures that the proposed scheme provides the session key (SK) security. Finally,we carry out the performance evaluation of the proposed scheme and other related schemes, and the result favors that the proposed scheme provides better trade-off among security and performance as compared to other existing related schemes.

Abstract

With the increasing use of mobile devices, a secure communication and key exchange become the significant security issues in mobile environments. However, because of open network envi-ronments, mobile user can be vulnerable to various attacks. Therefore, the numerous authentication and key exchange schemes have been proposed to provide the secure communication and key exchange.Recently, Qi and Chen proposed an efficient two-party authentication key exchange protocol for mobile environments in order to overcome the security weaknesses of the previous authentication and key exchange schemes. However, we demonstrate that Qi and Chen’s scheme is vulnerable to various attacks such as impersonation, offline password guessing, password change, and privileged insider attacks. We also show that Qi and Chen’s scheme does not provide anonymity, efficient password change mechanism, and secure mutual authentication. In this paper, to overcome the outlined above mentioned security vulnerabilities,we propose a secure and efficient two-party authentication key exchange protocol, called 2PAKEP, that hides user’s real identity from an adversary using a secret parameter. 2PAKEP also withstands various attacks, guarantees anonymity, and provides efficient password change mechanism and secure mutual authentication. In addition, we prove that 2PAKEP provides the secure mutual authentication using the broadly accepted Burrows–Abadi–Needham logic and the session key security using the formal security analysis under the widely accepted real-or-random model. Moreover, the formal security verification using the popular simulated software tool, Automated Validation of Internet Security Protocols and Applications,on 2PAKEP shows that the replay and man-in-the-middle attacks are protected. In addition, we also analyze the performance and security and functionality properties of 2PAKEP and compare these with the related existing schemes. Overall, 2PAKEP provides better security and functionality features, and also the communication and computational overheads are comparable with the related schemes. Therefore, 2PAKEPis applicable to mobile environment efficiently.

Abstract

Steerability is a characteristic non-local trait of quantum states lying in between entanglement and Bell non-locality. A given quantum state is considered to be steerable if it violates a suitably chosen steering inequality. A quantum state which otherwise satisfies a certain inequality can violate the inequality under a global change of basis, i.e., if the state is transformed by a non-local unitary operation. Intriguingly, there are states which preserve their non-violation (pertaining to the said inequality) under any global unitary operation. The present work explores the effect of global unitary operations on the steering ability of a quantum state which lives in two qubits. We characterize such states in terms of a necessary and sufficient condition on their spectrum. Such states are also characterized in terms of some analytic characteristics of the set to which they belong. Looking back at steerability the present work also provides a relation between steerability and quantum teleportation together with the derivation of a result related to the optimal violation of steering inequality. An analytic estimation of the size of such non-violating states in terms of purity is also obtained. Interestingly, the estimation in terms of purity also gives a necessary and sufficient condition in terms of Bloch parameters of the state. Illustrations from some signature class of quantum states further underscore our observations.

Abstract

The Internet of Things (IoT) is a system of physical as well as virtual objects (each with networking capabilities incorporated) that are interconnected to exchange and collect information locally or remotely over the Internet. Since the communication often takes place over the Internet, it is vulnerable to various security threats in an IoT environment. We first discuss essential security requirements that are needed to secure IoT environment. We also discuss the threat model and various attacks related to the IoT environment. We then present a taxonomy of security protocols for the IoT environment which includes important security services such as key management, user and device authentication, access control, privacy preservation, and identity management. We also present a comparative study of recently proposed IoT-related state-of-art security protocols in terms of various security and functionality features they support. Finally, we discuss some future challenges for IoT security protocols that need to be addressed in the future.

Abstract

Remote user authentication is a cryptographic mechanism through which a remote server verifies the legitimacy of an authorized user over an insecure communication channel. Most of the existing authentication schemes consider single-server environments and require multiple registrations of the sameuser for multiple servers. Moreover, most of these schemes do not consider biometric template revocation and error correction for noisy biometric signals. In addition, the existing schemes have several weaknesses,including stolen smart card attack, lack of user anonymity, user impersonation attack, and non-diversification of biometric data. To overcome these disadvantages, we propose a new three-factor authenticated key agreement scheme using a fuzzy commitment approach. The three factors used in the proposed scheme are the user’s password, smart card, and personal biometrics. The security of the proposed scheme is verified using a formal security analysis under the broadly accepted Real-Or-Random model for the session key security. The widely accepted Burrows-Abadi-Needham logic is also applied for mutual authentication between a legally registered user and a server, and formal security verification using the broadly accepted Automated Validation of Internet Security Protocols and Applications is performed for the proposed scheme through simulation to show that it is secure. In addition, the informal security analysis of the proposed scheme shows that the scheme can resist other known attacks. Finally, a comparative study of the proposed scheme with the existing related schemes is conducted to measure the trade off among the security and functionality features and the communication and computation costs

Abstract

We consider causality respecting (CR) quantum systems interacting with closed timelike curves (CTCs), within the Deutsch model. We introduce the concepts of popping-up and elimination of quantum information and use them to show that no-cloning and no-deleting, which are true in CR quantum systems, are no more valid in the same that are interacting with CTCs. We also find limits on the possibility of creation of entanglement between a CR system and a CTC, and the same between two CR systems in the presence of a CTC. We prove that teleportation of quantum information, even in its approximate version, from a CR region to a CTC is disallowed. Interestingly, we find that tweaking the Deutsch model, by allowing the input and output not to be the same, leads to a nontrivial approximate teleportation beyond the classical limit.

Abstract

The Internet of Drones (IoD) provides the coordinated access to controlled airspace for the Unmanned Aerial Vehicles (called drones). The on-going cheaper costs of sensors and processors, and also wireless connectivity make it feasible to use the drones for several applications ranging from military to civilian. Since most of the applications using the drones involved in the IoD are real-time based applications, the users (external parties) usually have their interest in getting the real-time services from the deployed drones belonging to a particular fly zone. To address this important issue in the IoD, there is a great need of an efficient and secure user authentication approach in which an authorized user (for example, a driver of an ambulance) in the IoD environment can be given access to the data directly from an accessed drone. In this article, we first discuss an authentication model used in the IoD communication. We then discuss some security challenges and requirements for the IoD environment. A taxonomy of various security protocols in the IoD environment is also discussed. We then emphasis on the study of some recently proposed user authentication schemes for the IoD communication. A detailed comparative study is done based on functionality features, security attacks, and also communication and computation costs. Through the rigorous comparative study of the existing schemes, we identify the strengths and weaknesses of the user authentication schemes for the IoD communication. Finally, we identify some of the challenges for the IoD that need to be addressed in the coming future

Abstract

In the recent years, vehicular adhoc networks (VANETs) can be an attractive choice for collecting and transferring the healthcare data of the passengers to the remote healthcare centers. In VANETs, some of the intermediate nodes may act as relay nodes in which case, these networks are called as vehicular relay networks (VRNs). However, the transmitted information in VRNs can be captured by intruders during transmission. Moreover, an attacker can launch selective forwarding, blackhole, and sinkhole attacks in the network, which may in turn degrade the network performance parameters like high end-to-end delay, low packet delivery ratio (PDR) and network throughput. Hence, to address these issues, a secure data dissemination scheme using VRNs is proposed. In the proposed scheme, first, a secure vehicular medical relay network system is designed for the users belonging to disconnected rural areas. The collected information is filtered at zonal levels before transmission to a nearby road side units, which further pass it to the incoming vehicles. Second, a secure passenger health monitoring network is designed which continuously monitors health services of the passengers traveling in different vehicles. The information collected through small body sensors installed in the vehicles act as data sets that is forwarded to the on-board monitoring unit within the vehicle. This collected data is then transmitted to centralized healthcare centers for processing by using VRNs. Lastly, a strong elliptic curve cryptography-based cryptographic solution is designed for secure communication among different vehicles. The performance of the proposed scheme is evaluated in various network scenarios with respect to different selected parameters, such as throughput, network delay, PDR, jitter, transmission and computation overheads, and key distribution overhead. The obtained results indicate that the proposed scheme provides improvement of 52% in average delay and 5% in PDR. This further indicates effective message delivery even with high mobility of the vehicles.