Device-to-device (D2D) communication presents a new paradigm in mobile networking to facilitate data exchange between physically proximate devices. The development of D2D is driven by mobile operators to harvest short range communications for improving network performance and supporting proximity-based services. In this paper, we investigate two fundamental and interrelated aspects of D2D communication, security and privacy, which are essential for the adoption and deployment of D2D. We present an extensive review of the state-of-the-art solutions for enhancing security and privacy in D2D communication. By summarizing the challenges, requirements, and features of different proposals, we identify lessons to be learned from existing studies and derive a set of “best practices.” The primary goal of our work is to equip researchers and developers with a better understanding of the underlying problems and the potential solutions for D2D security and privacy. To inspire follow-up research, we identify open problems and highlight future directions with regard to system and communication design. To the best of our knowledge, this is the first comprehensive review to address the fundamental security and privacy issues in D2D communication.

Device-to-device (D2D) communication is continuously evolving and engulfing a wide diversity of proximate services and applications, which is considered as one of the key technologies in the 5G ecosystem. It is argued that direct communications paradigm advantages may not be entirely captured without embracing the concepts of the social-domain. Following the explosion of social networks and smart mobile devices, social-interactions among mobile users enable the promotion of D2D co-operations. In this paper, we first present a systematic overview of the socially unaware technical challenges and the prospective applications to consolidate a background on D2D communications. Next, all the social features utilized in tackling and improving the technical issues and the applications are briefed, respectively. Then, we provide a comprehensive survey on socially aware D2D communications, where various features of social-domain are leveraged, such as ties, community, trust, and selfishness to tackle the D2D technical issues and improve the performance of prospective D2D applications. We categorize state-of-the-art socially aware D2D communications into two main sections. The first section considers technical issues, while the second section pertains to their applications to provide insightful information and motivate more in-depth studies in this area. For each aforementioned section, we overview technical aspects and classify the core contributions based on approaches used and the social features utilized. In the discussion section, we summarize the socially aware D2D communications and present lessons learned. Finally, we highlight the open research challenges in this field and predict future research trends.

Cloud computing is an innovative technique that offers shared resources for stock cache and server management. Cloud computing saves time and monitoring costs for any organization and turns technological solutions for large-scale systems into server-to-service frameworks. However, just like any other technology, cloud computing opens up many forms of security threats and problems. In this work, we focus on discussing different cloud models and cloud services, respectively. Next, we discuss the security trends in the cloud models. Taking these security trends into account, we move to security problems, including data breaches, data confidentiality, data access controllability, authentication, inadequate diligence, phishing, key exposure, auditing, privacy preservability, and cloud-assisted IoT applications. We then propose security attacks and countermeasures specifically for the different cloud models based on the security trends and problems. In the end, we pinpoint some of the futuristic directions and implications relevant to the security of cloud models. The future directions will help researchers in academia and industry work toward cloud computing security.

The Internet of vehicles (IoV) is increasingly being used to realize the vision of intelligent transportation systems with the rapid development of computation and communication technologies. However, numerous IoV applications rely on a central unit for storing and processing information and mediators for wireless transmission. This can lead to the leakage of sensitive data and high costs and delays. To address these issues and improve the efficiency of data storage, processing, and sharing in the IoV, we propose a vehicle-based secure blockchain consensus (VBSBC) algorithm. Our VBSBC algorithm overcomes the limitations and drawbacks of state-of-the-art approaches by leveraging blockchain technology and a consensus algorithm to ensure secure communication between vehicles. In addition, the algorithm includes an authentication process and a key distributing and request process, illustrated during vehicles' movement between different zones. In simulation results, our proposed VBSBC algorithm demonstrated high performance compared to existing approaches in terms of authentication delay, key processing time, attack detection rate, throughput, and packet loss rate.