A Novel Technique for the Generation and Application of Substitution Boxes (s-box) for the Image Encryption

The increasing applications of image processing have shifted the focus to the security of images during their transmission. In this work, the main focus is on the security of gray scale images against cryptanalysis attacks. A new model for encryption algorithm of the grayscale image is presented through substitution boxes (s-box). The proposed technique contained two parts; in the first part six different substitution boxes are generated from Galois field and linear fractional transformations. In the second part, the generated substitution boxes are used for the encryption process of message image. For the estimation of the strength of the proposed technique for nonlinearity and strict avalanche criteria, statistical tests and histogram analysis are performed on the substitution boxes and on the encrypted images respectively to check its resistance. The proposed algorithm is more robust as compared to other encryption techniques against attacks in insecure transmission paths.