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With the rapid development of Internet of Vehicles (IoV), vehicle-based spatial crowdsourcing (SC) applications have been proposed and widely applied to various fields. However, location privacy leakage is a serious issue in spatial crowdsourcing because workers who participate in a crowdsourcing task are required to upload their driving locations. In this paper, we propose a decentralized location privacy-preserving SC for IoV, which allows vehicle users to securely participate in SC with ensuring the task’s location policy privacy and providing multi-level privacy preservation for workers’ locations. Specifically, we introduce blockchain technology into SC, which can eliminate the control of vehicle user data by SC-server. We combine the additively homomorphic encryption and circle-based location verification to ensure the confidentiality of task’s location policy. To achieve multi-level privacy preservation for workers’ driving locations, we only reveal a grid where workers are located in. The size of the grid represents the level of privacy preservation. We leverage the order-preserving encryption and non-interactive zero-knowledge proof to prevent workers from illegally obtaining rewards by forging their driving locations. The security analysis results show that our framework can satisfy the above requirements. In addition, the experiment results demonstrate that our framework is efficient and feasible in practice. [ABSTRACT FROM AUTHOR]

The traditional covert communication that relies on a central node is vulnerable to detection and attack. Applying blockchain to covert communication can improve the channel's anti‐interference and antitampering. Whisper is the communication protocol of Ethereum, which mainly relies on payload to store information and padding to expand. These two fields can store a large amount of information, creating conditions for the realization of covert communication. In this paper, we propose a covert communication method based on the whisper protocol to covertly transfer information in the blockchain. To implement this method, we use payload to store the carrier information, matching it with the secret message. The generated index is recorded in the padding field. To improve the concealment of communication, we simulate the default filling rules of the protocol to maintain the message size. A new topic–key pair interaction method is also proposed to improve the security of the model. Moreover, the anti‐interference, antitampering and antidetection of the newly proposed model are verified through theoretical analysis and experiment. The experimental findings show that the amount of information in the proposed method is 4.7 times that of the traditional time‐based covert communication. The time consumption of information transmission is reduced to 52.25% under the same settings and even less in actual use. The cost of the new topic–key pair interaction is reduced by nearly 50% compared with the original method. [ABSTRACT FROM AUTHOR]

Along with the rapid growth of the size and complexity of Internet of Things (IoT), the security of terminal devices has increasingly become a focus. In order to ensure the security of terminals, the trusted network connect (TNC) could realize not only the user authentication but also the platform attestation during the network access process. However, the existing TNC infrastructure is based on a centralized architecture, which is not suitable for distributed services. To address this problem, we present a blockchain-based TNC protocol named BTNC to ensure the reliability of terminals in IoT. Due to the decentralization, trustlessness, trackability, and immutability features of blockchain, BTNC is able to verify the security of terminal devices in IoT networks. First, we come up with some threats, including unauthorized user, illegal platform and platform replacement attack, then correspondingly define the security goals of our scheme. Second, combining key exchange protocol based on blockchain and D–H PN protocol included in TNC specification, we propose a blockchain-based trusted network connection protocol, which realizes mutual user authentication, platform attestation and trust network access by cryptography among terminals in IoT. Third, we make a security analysis in the PCL mode and conclude that our protocol can resist the attacks above. Finally, the performance overheads caused by our scheme are evaluated and the experiments show that it is efficient and feasible for different kinds of terminals in IoT. • We put forward threat model and corresponding requirements based on trusted network connection in the distributed environment. • We propose BTNC, a novel blockchain-based network connection scheme in the distributed environment. Scheme BTNC can provide user authentication and platform attestation without trusted third party and therefore achieving mutual authentication among terminal devices. • We theoretically analyze the security of BTNC and the analysis shows that BTNC satisfies the requirements. • We report experimental evaluations of BTNC. Our results show that it is efficient and feasible for BTNC to achieve mutual verification among terminal devices in IoT. [ABSTRACT FROM AUTHOR]