A Novel Bit-level Image Encryption Algorithm Based on Coarse-grained Chaotic Signals

In this paper, a novel image encryption algorithm based on coarse-grained chaotic signals in which scrambling and diffusion are both covered. First, the chaotic signals are handled with unfixed coarse-grained key instead of been utilized directly. Second, both original image and derived chaotic signals are divided into bit signals form pixel values. In addition, high bits and low bits are also separated. Third, the high bits and low bits are scrambled with different methods at the same time and combined bit signals after scrambling are used to get the final results by global diffusion. At last, the image is encrypted and a corresponding decryption is designed to recover the encrypt image. In the simulation, properties including key space, information entropy, correlation analysis, key sensitivity and resistance to differential attack are provided to show the effectiveness and robustness of the high secure image encryption algorithm.