A chaos-based image encryption scheme using 2D rectangular transform and dependent substitution

Chaos-based image cryptosystems usually adopt the traditional confusion-diffusion architecture which is considered insecure against known/chosen plaintext attacks. To overcome this drawback, this paper proposes a novel chaos-based image encryption scheme, in which the two-dimensional rectangular transform is employed to directly scramble the image of any rectangular size, and the dependent substitution is introduced to substitute for each pixel according to the image pixels. This scheme comprises two stages of encryption processes. Each stage provides the confusion and diffusion simultaneously in one traverse of image pixels. As a result, the proposed scheme has high speed and achieves a satisfactory security performance. Experimental results and various types of security analysis indicate that this scheme is efficient and secure enough to be used for practical image encryption and transmission.