Integrated Confusion-Diffusion Mechanisms for Chaos Based Image Encryption

Abstract

Most block-cipher image encryption schemes based on chaos theory have independent modules for confusion and diffusion processes. None of the current schemes use chaos theory in the diffusion modules - thus not utilizing the capabilities of chaos to the fullest extent. We can do better: we integrate these mechanisms into a single step, thus making the encryption process efficient. This paper presents three novelties: (a) we extend 2D images to 3D by using grayscale image intensities in 8-bit binary form (b) we embed the diffusion mechanism into confusion by applying the 3D Baker map based confusion algorithm. Thus, the diffusion process is accomplished by a permutation of binary bits in the third dimension, eliminating the need for a separate diffusion process and (c) we extend the proposed method to color images by using the 24-bit color information. Color image encryption is usually performed by encrypting each channel independently and then combining these to get the encrypted image. We demonstrate that with this simplistic approach, decrypting even a single channel would reveal reasonable information contained in the image. In our approach, this drawback is eliminated because of the inherent dependence between the data contained in all the channels, thus highlighting the inherent superiority of the proposed algorithm for color image security.