Chaotic Image Encryption Algorithm Based on Bit-Combination Scrambling in Decimal System and Dynamic Diffusion

In this paper, an image encryption algorithm based on bit-combination scrambling and dynamic diffusion is proposed based on multiple chaotic systems. First, the plaintext image is scrambled. On the basis of the decimal system, the pixel value of the gray-scale plaintext image is divided into three groups: units, tens, and hundreds' digit. Each group performs different rounds of Arnold mapping, and the parameters of the Arnold mapping and the number of mapping wheels are determined by the plaintext image. The scrambled image is generated by combination. This algorithm avoids the periodicity of Arnold mapping. Second, the dynamic diffusion operation is designed. This operation can start from any position of the plaintext pixel value and combine chaotic sequence to do XOR around this point. Therefore, it has N modes of diffusion, where N is the number of pixel values. Third, this method is extended to color image encryption. The comparison test results show that this method has better security and can resist common attack methods.