Page 169 - 2024-Vol20-Issue2

Received: 19 July 2023 | Revised: 10 September 2023 | Accepted: 30 November 2023

DOI: 10.37917/ijeee.20.2.14 Vol. 20 | Issue 2 | December 2024

Open Access

Iraqi Journal for Electrical and Electronic Engineering

Original Article

Design of High-Secure Digital/Optical Double Color

Image Encryption Assisted by 9D Chaos and DnCNN

Rusul Abdulridha Muttashar*, Raad Sami Fyath
Department of Computer Engineering, Al-Nahrain University, Baghdad, Iraq

Correspondance
*Rusul Abdulridha Muttashar,
Department of Computer Engineering,
Al-Nahrain University, Baghdad, Iraq
Email: Rsusl97.abd@gmail.com

Abstract
With the rapid development of multimedia technology, securing the transfer of images becomes an urgent matter.
Therefore, designing a high-speed/secure system for color images is a real challenge. A nine-dimensional (9D) chaotic-
based digital/optical encryption schem is proposed for double-color images in this paper. The scheme consists of
cascaded digital and optical encryption parts. The nine chaotic sequences are grouped into three sets, where each set is
responsible for encryption one of the RGB channels independently. One of them controls the fusion, XOR operation,
and scrambling-based digital part. The other two sets are used for controlling the optical part by constructing two
independent chaotic phase masks in the optical Fourier transforms domain. A denoising convolution neural network
(DnCNN) is designed to enhance the robustness of the decrypted images against the Gaussian noise. The simulation
results prove the robustness of the proposed scheme as the entropy factor reaches an average of 7.997 for the encrypted
color lena-baboon images with an infinite peak signal-to-noise ratio (PSNR) for the decrypted images. The designed
DnCNN operates efficiently with the proposed encryption scheme as it enhances the performance against the Gaussian
noise, where the PSNR of the decrypted Lena image is enhanced from 27.01 dB to 32.56 dB after applying the DnCNN.

Keywords
Hybrid digital/optical encryption, 9D chaotic system, Double color image encryption, DnCNN, Chaotic-based image
encryption.

I. INTRODUCTION amplitude and phase information of all image pixels can be
processed simultaneously. Further, image encryption can be
As of advances in communication and networking technology, processed in various matrix spaces such as phase and polar-
research has been conducted on transmitting images securely ization, which offers additional security level and reliability.
in real-time [1–3]. Generally, secure transmission can be The general structure of OE schemes consists of lasers, spatial
achieved by applying image encryption algorithms at the trans- light modulators (SLMs), lenses, beam splitters, and detec-
mitter side and related decryption algorithms at the authorized tors [8]. A spatial light modulator is a general term describing
receiver side [4–6]. Recently, there has been increasing inter- devices that are used to modulate the amplitude, phase, or
est in using optical technology for encrypting gray and color polarization of light waves. The SLM produces transparency
images to achieve a high-speed encryption process [3, 4, 7]. controlled by the computer according to the image or mask
The optical encryption (OE) process treats the image directly required to modulate the light beam [10]. It is worth mention-
as a two-dimensional (2D) object. Therefore, it does not ing here that the operation of the OE scheme may be assisted
use image digitization as done in the digital encryption (DE) by DE algorithms to support certain functions which cannot
counterpart. Further, OE methods have some characteristic be implemented using the available optical and/or photonic
features due to the optical devices [8, 9]. For example, the

This is an open-access article under the terms of the Creative Commons Attribution License,
which permits use, distribution, and reproduction in any medium, provided the original work is properly cited.
©2024 The Authors.
Published by Iraqi Journal for Electrical and Electronic Engineering | College of Engineering, University of Basrah.

https://doi.org/10.37917/ijeee.20.2.14 |https://www.ijeee.edu.iq 165