Lightweight Dynamic Advanced Encryption Standard Encryption Based on S-Box Reconfiguration and Real-Time Key Expansion for Secure Over-the-Air Communication

The Advanced Encryption Standard (AES) symmetric encryption algorithm plays a crucial role in data encryption. To address the limitations of the fixed Substitution-box (S-box) and static key expansion strategy in AES. This paper proposes an improved AES scheme that integrates a dynamic S-box structure with a key expansion mechanism based on dynamic perturbations. The dynamic S-box is generated by selecting affine transformation pairs and irreducible polynomials, and its cryptographic properties are tested in SageMath9.3 to obtain a set of S-boxes superior to the standard AES. In the key expansion process, the perturbation values generated by the hash function will be incorporated into the round key generation process to reduce the correlation between round keys. The improved AES algorithm, when applied to Over-the-Air (OTA) systems, not only achieves significant savings in storage resources of in-vehicle Electronic Control Units (ECUs) but also enhances the security of OTA communications. Furthermore, it consumes only a small amount of ECU computational resources, thereby effectively meeting the lightweight requirements of in-vehicle electronic control units.