The Space Information Network (SIN) plays a crucial role in terrestrial communication, delivering time-bound services from ground stations to users. It relies on moving low-orbit earth (LEO) satellites for uninterrupted coverage. However, untrustworthy connectivity poses several security challenges during handover services for users maintained by the satellites. While traditional cryptographic techniques provide a degree of security, the advent of quantum computing exposes significant vulnerabilities. This work proposes a quantum-safe and continuous authentication mechanism with handover provision. The proposed authentication protocol uses post-quantum primitives of the Frodo key encapsulation mechanism, currently an approved mechanism under ISO/IEC 18033-2. It ensures privacy and ensures users’ anonymity. The security of the proposed protocol is analyzed using the quantum random oracle (QROM) model. Formal verification confirms its safety for practical adoption as a post-quantum candidate. Further, the performance evaluation shows an authentication delay and energy consumption of the proposed protocol within practical limits, making it a suitable candidate for privacy-preserved post-quantum adoption for SIN.

Broadcast encryption schemes for the standard Controller Area Network (CAN 2.0B) reduce bandwidth for data transmission from one electronic control unit (ECU) to others while assuring confidentiality. If received data is damaged, CAN 2.0B enables remote transmission request (RTR), allowing recipient ECUs to request retransmissions. However, retransmission for n ECUs increases the communication cost of current broadcast encryption techniques to a complexity O(n) for intra-vehicular networks (IVNs). This paper designs a novel broadcast encryption called SMEBE-CAN that retains its sublinear complexity of $O(\sqrt {\text{n}} )$ throughout IVN retransmissions. Besides, we devise a robust authenticated key exchange (AKE) protocol using SMEBE-CAN to address IVN data corruption during regular communication. Our protocol is provably secure in the standard model under the harness of the bilinear Diffie-Hellman exponent (BDHE) assumption. Besides, it is formally verified using the Scyther tool. As proof of concept, a performance comparison for 100 ECUs, with 10 ECUs per group, shows that the SMEBE-CAN has a lower authentication delay when ECUs are run at higher frequencies. Nonetheless, it ensures a lower bus load than related schemes, making it fit for practical usage.