An Efficient Nonlinear Post-Processing Applied to Image Encryption

In this paper, we propose an efficient non-linear post-processing placed downstream of an image encryption scheme. It consists firstly to encrypt the plaintext image by the confusion-diffusion technique using chaotic functions. Then, the resulting image is added to a chaotically generated image having the same dimensions. Obtained result passed through the arctangent function to give the encrypted image. Computer simulations have proven the support that a nonlinear function can give an image encryption scheme. In addition, the performance measurements carried out prove the superiority of the proposed method towards existing algorithms in the literature from the point of view of histogram analysis, correlation test and key space.