Visual selective image encryption can both improve the efficiency of the image encryption algorithm and reduce the frequency and severity of attacks against data. In this article, a new form of encryption is proposed based on keys derived from Deoxyribonucleic Acid (DNA) and plaintext image. The proposed scheme results in chaotic visual selective encryption of image data. In order to make and ensure that this new scheme is robust and secure against various kinds of attacks, the initial conditions of the chaotic maps utilized are generated from a random DNA sequence as well as plaintext image via an SHA-512 hash function. To increase the key space, three different single dimension chaotic maps are used. In the proposed scheme, these maps introduce diffusion in a plain image by selecting a block that have greater correlation and then it is bitwise XORed with the random matrix. The other two chaotic maps break the correlation among adjacent pixels via confusion (row and column shuffling). Once the ciphertext image has been divided into the respective units of Most Significant Bits (MSBs) and Least Significant Bit (LSBs), the host image is passed through lifting wavelet transformation, which replaces the low-frequency blocks of the host image (i.e., HL and HH) with the aforementioned MSBs and LSBs of ciphertext. This produces a final visual selective encrypted image and all security measures proves the robustness of the proposed scheme.

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.

To create confusion in ciphertexts, encryption processes depends upon nonlinear mappings. This nonlinear mapping can be achieved by a process known as substitution. In a secure encryption algorithm, substitution plays a key role during confusion stage of encryption algorithms. In this work, we present a novel chaos-based substitution box that can be utilized in the encryption processes for securing digital images from eavesdroppers. The proposed substitution box is also compared with other conventional substitution boxes presented in literature. Various statistical measures such as contrast, correlation, energy and homogeneity analysis prove the superiority of the proposed substitution box.