Edinburgh Napier University

  Due to development in Internet and networking technology, multimedia data is broadly transmitted via wired and wireless medium. Thus security is a major concern in modern communication systems. Encryption is one of the pre-eminent ways to guarantee security in many real time applications. In this paper, confusion and diffusion phenomenon is presented for digital images. The proposed scheme provides a secure image encryption/decryption scheme using two chaotic maps and substitution boxes. To confuse the relationship between plaintext and ciphertext images, both chaotic maps play a vital role in the confusion and diffusion process. In confusion process, the plaintext image is permuted row-wise and column-wise via two random sequences generated by Henon map. The pixel values diffusion is carried out by unimodel Skew tent map through XOR operation. Furthermore, in last step of the proposed scheme, image is divided into four blocks. To get a highly diffused ciphertext, four different Substitution Boxes (S-Boxes) are applied on each block. Extensive security analysis show that the proposed scheme provides an efficient security for digital images.