The third party misuse and manipulation of digital images is a threat to security and privacy of human subjects. The requirements to fulfil the security needs of digital images have led to the development of good encryption techniques. The proposed method of encryption scheme combines the techniques of chaotic image encryption and DNA (Deoxyribonucleic Acid) sequence operations. The encryption mechanism is applied separately on three channels (R, G and B) of the colour image with a suitable chaotic map. The map selection algorithm selects a good chaotic map based on image properties and other parameters. A method of DNA encoding is also applied after chaotic encryption. A new Mandelbrot Set based conditional shift algorithm is introduced to apply confusion effectively on R, G and B channels. Simulation and security analysis confirm that the proposed image encryption scheme demonstrates extraordinary performance in terms of security.

Introduction

The fast development of digital technologies and communication networks causes to generate more and more digital data [1]. Security and privacy of the images captured from electronic devices are of paramount importance with the increase in velocity, volume and veracity of the acquired multi-modal data. One effective well-known method to keep integrity is to encrypt the images by turning it from a meaningful version to a meaningless one [2]. Images have large data capacities, and it is known that a high correlation between adjacent pixels. So the traditional cryptosystems, such as RSA (Rivest–Shamir–Adleman), DES (Data Encryption Standard), AES (Advanced Encryption Standard), are not suitable for image encryption [3]. Recently, different kinds of image encryption algorithms based on optical transform, chaotic systems, Fourier transform, cellular automata, wavelet transform, magic cube, etc. have been studied by groups of researchers from all over the world [4]. There exist two groups in image encryption techniques based on the method applied to design the encryption and decryption system. Chaotic cryptography is the application of the mathematical chaos theory (that is, the chaotic sequences produced by chaotic maps) in the generation of cryptographic algorithms.