A novel binary operator for designing medical and natural image cryptosystems

Abstract

Image cryptosystems aim to secure the transmission of images in the presence of adversaries in the network. For ensuring confidentiality, images are encrypted to form unintelligible cipher images, the algorithms of which are much different from those for text data. Most image cryptosystems follow confusion–diffusion or complex architectures, which involves permutation and substitution of pixel values. Often these are done using chaotic maps and involve binary operations such as bitwise XOR, addition–subtraction, DNA operations, etc., each of which has certain limitations. Most of the cryptosystems for medical images proposed in the literature encrypt 8-bit compressed versions of the images rather than the standard 16-bit DICOM version, which results in loss of information. This paper presents a novel binary operation that can be used for all types of image cryptosystems — from DICOM medical to natural images using both conventional and DNA approaches. The use of this operation has been tested on a proposed DNA-based cryptosystem, which has novel steps for encryption to overcome the drawbacks of some existing ones. The cryptosystem has been tested on several images of varying pixel depth and dimensions, and the results obtained meet the standards of a secured image encryption system.