Security of multiple RGB images by RSA cryptosystem combined with FrDCT and Arnold transform

The security, efficiency, and storage of image data are global issues while transmitting images over the Internet. In this paper, we have fabricated a novel approach for security of multiple-color images utilizing asymmetric RSA cryptosystem, reality preserving fractional discrete cosine transform and Arnold transform. In our approach, three indexed images are obtained from three RGB color images by extracting their color maps. These three indexed images are taken as red, green and blue components of an RGB color image. Each element of an RGB image is first encrypted using RSA cryptosystem. The fractional discrete cosine transform is applied on the partially encrypted image which transforms the image data from the time domain to the frequency domain. Finally, Arnold transform dislocates the processed image. The security of the similar encryption schemes available in literature depends upon the secret keys only. If the secret keys are leaked, the encryption scheme is no more secure. Also, these schemes are secure either in the time domain or in the frequency domain. However, the security of our approach depends upon secret keys and their proper arrangements. The proposed method is secure in the time domain as well as in the frequency domain. Due to a single encrypted image, it is easy for storage and transmission over the Internet. Simulation analysis is done with standard examples to conclude that the proposed approach is robust. (C) 2020 Elsevier Ltd. All rights reserved.