The Internet of Things (IoT) has become increasingly popular in people's daily lives. The pervasive IoT devices are encouraged to share data with each other in order to better serve the users. However, users are reluctant to share sensitive data due to privacy concerns. In this paper, we study the anonymous data aggregation for the IoT system, in which the IoT company servers, though not fully trustworthy, are used to assist the aggregation. We propose an efficient and accountable aggregation scheme that can preserve the data anonymity. We analyze the communication and computation overheads of the proposed scheme, and evaluate the total execution time and the per-user communication overhead with extensive simulations. The results show that our scheme is more efficient than the previous peer-shuffle protocol, especially for data aggregation from multiple providers.
 Cloud-supported Internet of Things (Cloud-IoT) has been broadly deployed in smart grid systems. The IoT front-ends are responsible for data acquisition and status supervision, while the substantial amount of data is stored and managed in the cloud server. Achieving data security and system efficiency in the data acquisition and transmission process are of great significance and challenging, because the power grid-related data is sensitive and in huge amount. In this paper, we present an efficient and secure data acquisition scheme based on ciphertext policy attribute-based encryption. Data acquired from the terminals will be partitioned into blocks and encrypted with its corresponding access subtree in sequence, thereby the data encryption and data transmission can be processed in parallel. Furthermore, we protect the information about the access tree with threshold secret sharing method, which can preserve the data privacy and integrity from users with the unauthorized sets of attributes. The formal analysis demonstrates that the proposed scheme can fulfill the security requirements of the Cloud-IoT in smart grid. The numerical analysis and experimental results indicate that our scheme can effectively reduce the time cost compared with other popular approaches. Today's mobile smartphones are very powerful, and many smartphone applications use wireless multimedia communications. Mobile phone security has become an important aspect of security issues in wireless multimedia communications. As the most popular mobile operating system, Android security has been extensively studied by researchers. However, few works have studied mobile phone multimedia security. In this article, we focus on security issues related to mobile phone cameras. Specifically, we discover several new attacks that are based on the use of phone cameras. We implement the attacks on real phones, and demonstrate the feasibility and effectiveness of the attacks. Furthermore, we propose a lightweight defense scheme that can effectively detect these attacks. Sensor random locations and sensor failures can cause coverage holes, routing voids and disconnections and thus degrade sensor network performance. In this paper, we present a self-healing approach that utilises a few mobile sensors to deal with the problems. A mobile sensor can move to an area with a coverage hole or routing void and significantly improve network performance. We design distributed algorithms to detect coverage holes, estimate hole size and repair holes. A mobile sensor may receive multiple repair requests from different areas and it may not have complete information of the network. We present a fuzzy-logic-based distributed decision-making algorithm for mobile sensors. Extensive simulations demonstrate the good performance of proposed algorithms. Wireless sensor networks have many applications, vary in size, and are deployed in a wide variety of areas. They are often deployed in potentially adverse or even hostile environment so that there are concerns on security issues in these networks. Sensor nodes used to form these networks are resource-constrained, which make security applications a challenging problem. Efficient key distribution and management mechanisms are needed besides lightweight ciphers. Many key establishment techniques have been designed to address the tradeoff between limited memory and security, but which scheme is the most effective is still debatable. In this paper, we provide a survey of key management schemes in wireless sensor networks. We notice that no key distribution technique is ideal to all the scenarios where sensor networks are used; therefore the techniques employed must depend upon the requirements of target applications and resources of each individual sensor network.   Recent advances in electronics and wireless communication technologies have enabled the development of large-scale wireless sensor networks that consist of many low-power, low-cost, and small-size sensor nodes. Sensor networks hold the promise of facilitating large-scale and real-time data processing in complex environments. Security is critical for many sensor network applications, such as military target tracking and security monitoring. To provide security and privacy to small sensor nodes is challenging, due to the limited capabilities of sensor nodes in terms of computation, communication, memory storage, and energy supply. In this article we survey the state of the art in research on sensor network security.  Implantable Medical Devices (IMDs) are widely used to treat chronic diseases. Nowadays, many IMDs can wirelessly communicate with an outside programmer (reader). However, the wireless access also introduces security concerns. An attacker may get an IMD reader and gain access to a patient's IMD. IMD security is an important issue since attacks on IMDs may directly harm the patient. A number of research groups have studied IMD security issues when the patient is in nonemergency situations. However, these security schemes usually require the patient's participation, and they may not work during emergencies (e.g., when the patient is in comma) for various reasons. In this paper, we propose a light-weight secure access control scheme for IMDs during emergencies. Our scheme utilizes patient's biometric information to prevent unauthorized access to IMDs. The scheme consists of two levels: level 1 employs some basic biometric information of the patient and it is lightweight; level 2 utilizes patients' iris data for authentication and it is very effective. In this research, we also make contributions in human iris verification: we discover that it is possible to perform iris verification by comparing partial iris data rather than the entire iris data. This significantly reduces the overhead of iris verification, which is critical for resource-limited IMDs. We evaluate the performance of our schemes by using real iris data sets. Our experimental results show that the secure access control scheme is very effective and has small overhead (hence feasible for IMDs). Specifically, the false acceptance rate (FAR) and false rejection rate (FRR) of our secure access control scheme are close to 0.000 with suitable threshold, and the memory and computation overheads are acceptable. Our analysis shows that the secure access control scheme reduces computation overhead by an average of 58 .