An Block Image Encryption Algorithm Based on Reversible Cellular Automata

Abstract

This article proposed a block image encryption scheme based on reversible cellular automata (RCA) and chaotic systems in order to construct an image encryption scheme with great confidentiality effect and high encryption and decryption efficiency. In the preparation phase of this algorithm, the original image is transformed into the frequency domain using the method of integer wavelet transform (IWT). The IWT divides the plaintext image into four frequency blocks. The low-frequency image block containing critical information is treated differently from other high-frequency image blocks in the following procedure. In order to avoid direct processing of image blocks with visual significance, a combined one-dimensional chaotic map is used to rearrange the pixel positions within the image blocks respectively. The chaotic map is then used to acquire various RCA rules and iterations. According to the different importance of the information stored in the image block, the RCA evolution of the image block is carried out with different rules and different iteration times. Finally, the image is scrambled and diffused around the whole image to reduce the blocking effect. The algorithm blocks the images according to different importance and encrypts them at different levels. Avoiding the waste of time and resources caused by the same operation on the whole image.