Vehicular ad-hoc network (VANET) has been considered as one of the most promising wireless sensor technologies, which could enhance driving convenience and traffic efficiency through real-time information interaction. Nevertheless, emerging security issues (e.g., confidentiality, integrity, identity privacy, message authentication) will hinder the widespread deployment of VANETs. To address these issues, in this paper, we propose an efficient privacy-preserving anonymous authentication protocol for VANETs. We first design an identity-based signature algorithm, and exploit it with an account information of a vehicle to propose our anonymous authentication protocol. The protocol enables each vehicle to anonymously send an authenticated message to nearby roadside units (RSUs) in a confidential way, and efficiently check the feedback information from nearby RSUs. Simultaneously, the protocol achieves key-exchange functionality, which could produce a session key for later secure communication between vehicles and RSUs. Finally, we give the security analysis of the proposed protocol and conduct a comprehensive performance evaluation, the results demonstrate its feasibility in the secure deployment of VANETs.
To cope with the computational and energy constraints of mobile devices, Mobile Edge Computing (MEC) has recently emerged as a new paradigm that provides IT and cloud-computing services at mobile network edge in close proximity to mobile devices. This paper investigates the energy consumption problem for mobile devices in a multi-user MEC system with different types of computation tasks, random task arrivals, and unpredictable channel conditions. By jointly considering computation task scheduling, CPU frequency scaling, transmit power allocation and subcarrier bandwidth assignment, we formulate it as a stochastic optimization problem aiming at minimizing the power consumption of mobile devices and to maintain the long-term stability of task queues. By leveraging the Lyapunov optimization technique, we propose an online control algorithm (OKRA) to solve the formulation. We prove that this algorithm is able to provide deterministic worst-case latency guarantee for latency-sensitive computation tasks, and balance a desirable tradeoff between power consumption and system stability by appropriately tuning the control parameter. Extensive simulations are carried out to verify the theoretical analysis, and illustrate the impacts of critical parameters to algorithm performance.
