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.

To improve the security of mobile networks in the postquantum era, Dabra et al. recently proposed a lattice-based anonymous password-authenticated key exchange (LBA-PAKE) protocol for mobile devices. Especially, LBA-PAKE is claimed to support the key reuse. However, we find that LBA-PAKE is still vulnerable to the signal leakage attack when the master key is reused. We propose two strategies to reduce the needed number of queries in our attack. Compared to the method of Bindel et al. , our method reduces the required queries by more than 75%. Our experiments show that breaking LBA-PAKE needs less than 2 min. Through analysis of why LBA-PAKE fails in their security proof, we further propose an improved protocol without incurring extra computation costs. The formal security analysis shows that our improved scheme supports all features of LBA-PAKE while thwarting the signal leakage attack. Moreover, the implementation of our improved protocol demonstrates its efficiency in mobile networks.

On account of the recent advances in quantum computers, it becomes pressing to consider quantum-safe authentication schemes for two-way communications in neighborhood area networks of smart grid, i.e., preventing possible attacks that the quantum computers could bring to the grid. In this paper, we take a further step toward this goal by integrating the lattice based public-key encryption and key exchange techniques to provide mutual authentication between smart meters and the neighborhood gateway. Security analysis shows that our proposed scheme is secure under attacks from both quantum and conventional computers, including the recently introduced key reuse attacks. In addition, the proposed schemes can also achieve forward security, which guarantees that the secrets leaked in the current session will not result in the leakage of secrets in former sessions. Furthermore, the proposed scheme also gives prior consideration to the smart meters with limited computation capacity and puts as less burden on them as possible. Extensive performance analysis is also conducted, and the results demonstrate the efficiency of our proposed scheme, as well as the relatively low communication and storage costs.