Double image encryption method using the Arnold transform in the fractional Hartley domain

Abstract

ABSTRACT A new method for double image encryption based on the fractional Hartley transform (FrHT) and the Arnoldtransform (AT) is proposed in this work. The encryption method encodes the rst input image in amplitudeand the second input image is encoded in phase, in order to de ne a complex image. This complex imageis successively four times transformed using FrHT and AT, and the resulting complex image represents theencrypted image. The decryption method is the same method as the encryption method applied in the inversesense. The AT is a process of image shearing and stitching in which pixels of the image are rearranged. This ATis used in the encryption method with the purpose of spreading the information content of the two input imagesonto the encrypted image and to increase the security of the encrypted image. The fractional orders of the FrHTsand the parameters of the ATs correspond to the keys of the encryption-decryption method. Only when all ofthose keys are correct in the decryption method, the two original images can be recovered. We present digitalresults that con rm our approach.Keywords: Encryption-decryption method, fractional Hartley transform, Arnold transform.