Title: ArMTFr: a new permutation-based image encryption scheme

Authors: Hassan Elkamchouchi; Wessam M. Salama; Yasmine Abouelseoud

Addresses: Electrical Engineering Department, Faculty of Engineering, Alexandria University, Egypt ' Department of Basic Sciences, Pharos University, Egypt ' Engineering Mathematics Department, Faculty of Engineering, Alexandria University, Egypt

Abstract: In this paper, a new image encryption scheme named (ArMTFr) is proposed. An image is encrypted using a combination of keyed permutations and substitution, where a fractal is XORed with the scrambled image. Fractal images are employed in order to improve the performance of the encryption scheme from the viewpoint of randomisation and to increase the encryption key space, thus boosting its security. The employed permutations are the Arnold map and Mersenne-Twister's permutation algorithm. Before the encryption process starts, histogram equalisation is used to enhance the contrast of the image by transforming the intensity values in it, so that the histogram of the output image approximately matches a uniform histogram. First, greyscale images are considered and then the basic algorithm is extended to handle coloured images. Three representations for coloured images are considered: RGB, YCbCr and HSI colour spaces. The security of the algorithm is enhanced in this case by applying RGB colour channels multiplexing. The experimental results show that the encrypted image has low correlation coefficients among adjacent pixels and a good histogram distribution, as well as resistance to various attacks.

Keywords: correlation; image encryption; histogram equalisation; pixel permutation; Arnold map; fractals.

DOI: 10.1504/IJESDF.2019.096516

International Journal of Electronic Security and Digital Forensics, 2019 Vol.11 No.1, pp.1 - 28

Received: 23 Mar 2017
Accepted: 15 Jan 2018

Published online: 05 Dec 2018 *

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