The real-time electricity consumption data can be used in value-added service such as big data analysis, meanwhile the single user's privacy needs to be protected. How to balance the data utility and the privacy preservation is a vital issue, where the privacy-preserving data aggregation could be a feasible solution. Most of the existing data aggregation schemes rely on a trusted third party (TTP). However, this assumption will have negative impact on reliability, because the system can be easily knocked down by the denial of service attack. In this paper, a practical privacy-preserving data aggregation scheme is proposed without TTP, in which the users with some extent trust construct a virtual aggregation area to mask the single user's data, and meanwhile, the aggregation result almost has no effect for the data utility in large scale applications. The computation cost and communication overhead are reduced in order to promote the practicability. Moreover, the security analysis and the performance evaluation show that the proposed scheme is robust and efficient.

Federated learning (FL) is a kind of privacy-aware machine learning, in which the machine learning models are trained on the users side and then the model updates are transmitted to the server for aggregating. As the data owners need not upload their data, FL is a privacy-persevering machine learning model. However, FL is weak as it suffers from a reverse attack, in which an adversary can get users data by analyzing the user uploaded model. Motivated by this, in this paper, based on the secret sharing, we design EPPDA, an efficient privacy-preserving data aggregation mechanism for FL, to resist the reverse attack, which can aggregate users trained models secretly without leaking the users model. Moreover, EPPDA has efficient fault tolerance [1] for the user disconnection. Even if a large number of users are disconnected when the protocol runs, EPPDA will execute normally. Analysis shows that the EPPDA can provide a sum of locally trained models to the server without leaking any single users model. Moreover, adversary can not get any non-public information from the communication channel. Efficiency verification proves that the EPPDA not only protects users privacy but also needs fewer computing and communication resources.

The fifth-generation (5G) mobile communication technology with higher capacity and data rate, ultra-low device to device (D2D) latency, and massive device connectivity will greatly promote the development of vehicular ad hoc networks (VANETs). Meantime, new challenges such as security, privacy and efficiency are raised. In this article, a hybrid D2D message authentication (HDMA) scheme is proposed for 5G-enabled VANETs, in which a novel group signature-based algorithm is used for mutual authentication between vehicle to vehicle (V2V) communication. In addition, a pre-computed lookup table is adopted to reduce the computation overhead of modular exponentiation operation. Security analysis shows that HDMA is robust to resist various security attacks, and performance analysis also points out that, the authentication overhead of HDMA is more efficient than some traditional schemes with the help of the pre-computed lookup table in V2V and vehicle to infrastructure (V2I) communication.

In order to protect the privacy of individual data, meantime guaranteeing the utility of big data, the privacy preserving data aggregation is widely researched, which is a feasible solution since it not only preserves the statistical feature of the original data, but also masks single user’s data. With smart meter owning the capability of connecting to Internet, the aggregation area extends to the virtual area rather than a traditional physical area. However, in a virtual aggregation area, the users’ membership maybe frequently changes, if while executing the aggregation protocol for the traditional area, the overhead is not ignorable. In this paper, the homomorphic encryption and ID-based signature are employed to design a dynamic membership data aggregation (DMDA) scheme, which reduces the complexity on a new user’s joining and an old user’s quitting. In addition, the operation center obtains the sum of the data in the virtual aggregation area, meantime knows nothing about single user’s data. Comparing with traditional privacy-preserving data aggregation scheme, DMDA is more suitable for next-generation smart grid and other Internet of Things environments.

Message authentication and conditional privacy preservation are two critical security issues in vehicular ad hoc networks (VANETs), which have been extensively studied in recent years. To achieve these security issues, many information security technologies have been proposed so far. Among them, pseudonyms-based and group-based messages signing and verifying are two of the main methods adopted in recently published literature. However, analysis points out that both of the two technologies have their downsides. To address these issues, a secure and efficient message authentication protocol (SEMA) is proposed in this article, which aims to achieve mutual authentication among vehicles and road-side units (RSUs) in VANETs by combining the advantages of pseudonyms-based and group-based methods. Security analysis shows that SEMA is robust to various security attacks. Performance evaluation demonstrates that SEMA is computationally lightweight on both vehicles and RSUs. Finally, simulations are performed to prove the feasibility in highway and urban environment.