Deep Learning (DL) algorithms based on artificial neural networks have achieved remarkable success and are being extensively applied in a variety of application domains, ranging from image classification, automatic driving, natural language processing to medical diagnosis, credit risk assessment, intrusion detection. However, the privacy and security issues of DL have been revealed that the DL model can be stolen or reverse engineered, sensitive training data can be inferred, even a recognizable face image of the victim can be recovered. Besides, the recent works have found that the DL model is vulnerable to adversarial examples perturbed by imperceptible noised, which can lead the DL model to predict wrongly with high confidence. In this paper, we first briefly introduces the four types of attacks and privacy-preserving techniques in DL. We then review and summarize the attack and defense methods associated with DL privacy and security in recent years. To demonstrate that security threats really exist in the real world, we also reviewed the adversarial attacks under the physical condition. Finally, we discuss current challenges and open problems regarding privacy and security issues in DL.

The large amount of driving data can help intelligent vehicles make decisions to drive safely, improve vehicular services and enhance driving experience. In traditional vehicular networks, data sharing needs to be done with roadside units (RSUs). However, RSUs cannot be entirely trusted and the data stored in the RSUs may be tampered with. In addition, the deployment of RSUs along roads consumes a large amount of social resources. Further, data sharing between vehicles lacks a trusted environment, and vehicles may be unwilling to share data with others because of data security and privacy concerns. Moreover, in the event of unauthorized data sharing, the source of the leaked data is difficult to trace. In this study, we exploit consortium blockchain technology to achieve traceable and anonymous vehicle-to-vehicle (V2V) data sharing, effectively preventing second-hand sharing of data. The combination of 5G and blockchain makes it possible to share data without using RSUs. We design an enhanced delegated proof-of-stake consensus algorithm to make it more suitable for applications in the distributed Internet of Vehicles (IoV). A comprehensive analysis shows that the proposed scheme is secure and efficient.

Traditional public key infrastructure-based authentication schemes provide vehicular networks with identity authentication and conditional privacy protection, which are not sufficient for assessing the credibility of messages. Additionally, although the new generation of cellular networks (5G) can dramatically improve the transmission efficiency of the messages, many existing authentication schemes are based on complex bilinear pairing operations, and the calculation time is too long to be suitable for delay-sensitive 5G-enabled vehicular networks. To address these issues, we propose a reputation system-based lightweight message authentication framework and protocol for 5G-enabled vehicular networks (RSMA). The trusted authority (TA) is in charge of reputation management. A vehicle with a reputation score below the given threshold cannot obtain a credit reference from the TA for participating in the communication; therefore, the number of untrusted messages in vehicular networks is reduced from the source. Security analysis shows that our scheme is secure against an adaptively chosen-message attack, and also satisfies a series of requirements of vehicular networks. The scheme is based on the elliptic curve cryptosystem and supports batch authentication; therefore, it shows better performance in terms of time consumption when compared with related schemes.

Vehicles gather data collected by sensor nodes, combined with messages obtained from the other nodes in vehicular ad hoc networks (VANETs), to achieve safe driving. An announcement type of message is sent in the VANET; it is collected by mobile vehicles, uploaded to a cloud server for storage, and provided to other vehicles for reference. However, in an open cloud environment, plaintext data are vulnerable to unauthorized access and even malicious tampering. To solve this issue, we propose an attribute-based encryption algorithm using blockchain, which is maintained by a roadside unit (RSU). The uploader's symmetric key is recorded on the blockchain, and all uploaded and accessed transactions are recorded for auditing. Our scheme can achieve the function of securely accessing different types of announcement messages according to different vehicle attributes. Security analysis and experimental results indicate that our scheme has achieved a balance between security and efficiency.

As an emerging concept in the intelligent transportation system (ITS), Opportunistic Autonomous Vehicle Platoon (OAVP) enables autonomous vehicles to self-organize a temporary platoon and travel together. Whereas, electing the platoon leader is a crucial issue to be solved in this scenario. The platoon leader not only suffers from more wind resistance but also spends more computation resources in dealing with tremendous information obtained from the surrounding environment. Hence, vehicles tend to be a follower rather than a leader. In this paper, we propose a reputation-based leader election system for OAVP named RLE, which contains two sub-systems: leader election and incentive mechanism. In the former one, a reputation-based election scheme is first constructed to elect a relatively trustful leader according to the reputation value recorded on the blockchain. The proposed scheme integrates previous experience with recommendations from other members. In the second sub-system, an incentive mechanism is designed to stimulate platoon members to participate actively in the process of election, which is based on the recorded real-time fuel economy among vehicles participating in a platoon. Security analysis shows that the system is sufficient to deal with potential security threats. Experimental results based on the simulated platform demonstrate the practicality and feasibility of our solution.

Cloud-Fog-Assisted Internet-of-Things (IoT) is a convincing paradigm to provide users with on-demand and low-latency services through Fog nodes in the edge of multiple clouds (Multi-Cloud). Multi-Cloud is a scalable multi-domain service-oriented net-centric system and can respond to complicated user requirements leveraging Multi-Cloud Service Composition (MCSC). However, in MCSC, user security can be easily compromised by untrusted and curious cloud service providers that may collect and violate the privacy and other essential assets of cloud users. Although many trust-based MCSC solutions have been proposed to seek a trustworthy composite service with highest trust level, most of them are vulnerable to malicious users intending to break through the clouds and inflict serious data leakage or asset damage. Considering these security concerns on both malicious users and untrusted service providers, in this paper, we present a trust-based secure multi-cloud collaboration framework for Cloud-Fog-Assisted IoT systems. Specifically, to guarantee the security of users, we develop a role-based trust evaluation method to enhance the trustworthiness of MCSC. To preserve the security of services, we design an efficient user authentication scheme and a secure collaboration scheme to provide collaborative user authentication and access control mechanism for MCSC. We evaluate its performane with extensive experiments