The vehicle-to-grid (V2G) network is an infrastructure for electric vehicles (EVs) to be charged and discharged. As EVs are increasingly connected to V2G networks, V2G networks are facing serious data security problems. Attackers may eavesdrop on, tamper with, and forge the electricity transaction data, which will seriously damage the security of the transmitted data and affect the V2G network's normal operation. To ensure secure and efficient transmission of electricity transaction data, a pairing-free certificateless agregate signcryption (PCAS) scheme is proposed in this article. The PCAS scheme is theoretically proven to provide confidentiality, unforgeability, etc. On the premise of ensuring data security, time-consuming pairing operation is avoided in the PCAS scheme, the certificateless mechanism is used to avoid certificate management and key escrow issues, the verification time of ciphertext is reduced by using aggregate signcryption, and the special random number processing method is adopted to reduce the complexity of signcryption process. The scheme is more efficient by adopting these measures. The performance analysis results demonstrate that the PCAS scheme takes less computing time than compared schemes. When massive EVs are charged and discharged through V2G networks, the data are transmitted more securely and efficiently by using the PCAS scheme.

Smart meters in advanced metering infrastructure (AMI) collect fine-grained, real-time power consumption data may result in user privacy leakage. Aiming at the problem that existing privacy protection schemes cannot resist quantum attacks, an antiquantum privacy protection scheme in AMI of smart grid based on consortium blockchain and ring learning with errors (RLWE) is proposed. The scheme has the following contributions. First, the RLWE-based secure communication scheme is designed in this article, which ensures the resistance of the scheme to quantum attacks. Second, all smart meters in AMI use anonymous identity to communicate with the control center, and the fine-grained power consumption data is also encrypted and digitally signed to prevent user privacy leakage and tampering of power consumption data. And the scheme does not use bilinear pairings and exponential operations and has efficient computational performance. Third, a two-tier consortium blockchain storage system consisted of regional gateways and data aggregators are designed to eliminate the single point of failure problems of the data aggregators. The practical byzantine fault tolerance consensus mechanism is improved to reduce the communication cost in the consensus process. The scheme's security is proven theoretically, and the experimental results show that the scheme has a low computational cost.