Design of Lightweight Chaotic SM4 System for Low-Altitude Communication Networks

The deep integration of edge computing, blockchain, and UAV technology with the low-altitude economy has rapidly expanded the scale and scope of low-altitude communication networks. To support the rapid development of the low-altitude economy, the number of heterogeneous terminal devices is growing exponentially, posing new challenges to data transmission security within low-altitude data networks. Most UAVs and terminal devices adopt lightweight designs to maintain flight weight, resulting in limited computational and storage resources that cannot support mature cryptographic schemes. This vulnerability makes data collected by such devices susceptible to eavesdropping and tampering. Furthermore, standard symmetric encryption algorithms fail to decouple the spatio-temporal correlation of data within low-altitude networks, creating security risks of interception or modification in open low-altitude network environments. This paper designs and implements a highly secure, lightweight, low-altitude data encryption protection scheme based on the SM4 cryptographic algorithm and chaos theory. A hardware-software co-processing encryption system was developed on the ZYNQ platform. This solution introduces chaotic mappings into the SM4 key expansion phase in the software layer to enhance network security, while a cyclic reuse architecture and dual-buffer structure achieve low resource overhead algorithm acceleration on the programmable hardware layer, ensuring data throughput. Verification results from the FPGA-based test platform demonstrate that the proposed system exhibits effectiveness and efficiency under low resource overhead conditions. It can be deployed as an endpoint or additional module within low-altitude networks to safeguard data security.