Novel method for image security system based on improved SCAN method and pixel rotation technique

Image scrambling is the conversion of images to unreadable format for security reasons. Encrypting an image with an acceptable level of security requires a cryptography system that follows the rules of confusion and diffusion. This paper introduces the SCAN method for scrambling and pixel rotation for diffusion. This image encryption method uses a knight tour to generate a scrambling key that is equal to the image size. The main advantage of this generator is that only a small initial value is needed to generate a full image size key. To realize confusion, a plain image is applied with an improved discrete diagonal SCAN (D-SCAN) method to generate a scrambled image for confusion. Then, to achieve diffusion, pixel values are changed by rotating all image pixels according to the generated keys. Results of statistical and security tests indicate that the proposed systems of D-SCAN and pixel rotation scheme can achieve excellent scrambling effect, high security, strong robustness against several attack types, and high sensitivity.