Hybrid chaotic image encryption in spatial-frequency domain integrated with bit-level dynamic diffusion

We aimed to address the issues of low encryption complexity and insufficient resistance to statistical attacks in chaotic image encryption algorithms. This paper proposes a novel method that combines hash scrambling, and bit-level transformation, leveraging the synergy between chaotic mapping and spatial-frequency transformation. Firstly, a specific hash function is constructed using the cubic chaotic system to achieve efficient scrambling of the image. Subsequently, the frequency domain data is generated by the Fourier transform and represented in the form of an optimized complementary code. Finally, the encryption is completed by DNA primary diffusion, secondary diffusion based on adjacent blocks, and the neighbor bit deprivation operation, and the entire process is jointly regulated by the Chen chaotic system and the Sin-Tent-Cos chaotic system. The experiment demonstrates that this scheme exhibits excellent robustness and security, with all indicators surpassing those of traditional methods. In particular, its resistance to differential attacks is close to the theoretical optimal value, demonstrating the important application potential of spatial-frequency joint encryption.