Vehicular Ad hoc Networks (VANETs) are one of the pillars of the Internet of Vehicles, they provide plenty of applications ranging from safety to entertainment. Safety applications largely depend on reliable and authentic traffic-related data. However, ensuring the data reliability and authenticity is facing many challenges due mainly to the scalability of VANETs such as the high speed, the long roads, and the open nature of VANETs. This paper addresses these challenges by proposing a decentralized Blockchain-based trust management framework (BC-TMF) aiming to compute trust metrics for vehicles. These trust metrics rely on the authenticity of the messages. Each vehicle assesses the authenticity of the received messages in real-time, calculates a local trust metric for the originator of such messages, then shares it with a miner. Periodically each miner aggregates the received trust metrics into global trust metrics, then packs them in a block. To investigate the efficiency and consistency of the proposed framework, extensive simulations are conducted. The obtained results show that the proposed BC-TMF has an excellent capability in computing accurate trust metrics for vehicles. Besides, it outperforms the existing ones in terms of the accuracy of computed trust metrics, particularly for malicious vehicles.

The Smart Grid (SG) aims to cope with the problems of the traditional grid, using renewable power generators. Similarly, SG benefits from the deployment of wireless sensor networks (WSNs) to enhance its aspects by monitoring the physical behavior of the power generators. However, new threats and attacks may arise due to the open nature and large scale of SG where WSNs are deployed. In this paper, we propose a new security architecture for WSNs in SG based on public key infrastructure (PKI). The key idea of the proposed architecture is to distribute the role of the certification authority (CA) among a set of sensor nodes to ensure the availability and scalability of the CA services. To elect this set of sensor nodes, we propose a novel lightweight clustering algorithm for WSNs that relies on the trust metrics of the nodes and their energy levels. The proposed architecture provides many security services such as authentication and confidentiality and mitigates many types of attacks such as Sybil and eavesdropping. Extensive simulations have been conducted using network simulator OMNET++ and Castalia framework to investigate the performance of the clustering algorithm. The results show that almost 100% of the sensors are members of clusters, and even in the presence of malicious nodes, the number of cluster heads remains static which reflects the robustness of the proposed architecture.