A novel image encryption based on row-column, masking and main diffusion processes with hyper chaos

Abstract

In this paper, a novel algorithm for image encryption based on the hyper-chaotic system is proposed. In order to generate the initial conditions of the hyper-chaotic system, 256-bit long external secret key is used. The algorithm consists of three main sections. In the first section, instead of encrypting each pixel, the rows and columns of the image are encrypted using a row-column algorithm. In order to reach higher sensitivity, higher complexity and higher security, the second section employs masking process which is applied to each quarter of the image (i.e. sub-images) that is to be encrypted, using that sub-image data itself and one of the other sub-images and the average data of other quarters of image. Finally in the last diffusion section, the four most significant bit planes will be encrypted. Experimental results and performance analysis prove the viability of this cryptography based on privacy, integrity and authenticity. It is demonstrated that 2D Correlation Coefficients (CC), Mean Absolute Error (MAE), Encryption Quality (EQ), Mean Square Error (MSE), Peak Signal-to-Noise Ratio (PSNR), the Number of Pixel Change Rate (NPCR), the Unified Average Changing Intensity (UACI), entropy and decryption quality can satisfy security and performance requirements (CC? ?80, EQ?>?210.90, MSE?>?9555, PSNR? ?99.61243%, UACI?>?33.47573% and Entropy?>?7.99734). It can be seen that this algorithm yields better security performance in comparison to the results obtained from other algorithms.