Hiding algorithm based fused images and Caesar cipher with intelligent security enhancement

International Journal of Electrical and Computer Engineering (IJECE)
Vol. 13, No. 6, December 2023, pp. 6797~6805
ISSN: 2088-8708, DOI: 10.11591/ijece.v13i6.pp6797-6805  6797
Journal homepage: http://ijece.iaescore.com
Hiding algorithm based fused images and Caesar cipher with
intelligent security enhancement
Huda Hussein Abed, Aqeel Sajjad Shaeel, Ruaa Shallal Abbas Annoze
Engineering Technical College-Najaf, Al-Furat Al-Awsat Technical University, Najaf, Iraq
Article Info ABSTRACT
Article history:
Received Mar 18, 2023
Revised May 21, 2023
Accepted Jun 4, 2023
The process of sending confidential data through the communication media
and in complete secrecy is now necessary, whether the data is related to
patients, a particular military operation, or a specified office. On the other
hand, with the development of various ciphering algorithms, and information
hiding algorithms, there is a need to obtain ciphered and hidden data
securely without the need to exchange secret keys between the two ends of
the communication. In this paper, a hiding algorithm based on fused images
and Caesar cipher with intelligent methods to strengthen the security of
confidential information is proposed. Firstly, fused image scattering is
obtained using 1’s complement and circularly shifting the bits of fused
pixels by specified positions before the hiding process. Secondly, the keys
for the Caesar cipher are derived from the length of secret information
according to the mathematical equation. Thirdly, strengthen the security of
Caesar’s cipher by taking a 1’s complement of each letter in the cipher data.
The results guarantee the security of the presented algorithm.
Keywords:
1’s complement
Caesar cipher
Fused images
Hiding algorithm
Intelligent methods
This is an open access article under the CC BY-SA license.
Corresponding Author:
Huda Hussein Abed
Department of Communication Techniques Engineering, Engineering Technical College-Najaf, Al-Furat
Al-Awsat Technical University
Najaf, Iraq
Email: eng.huda2020@atu.edu.iq
1. INTRODUCTION
Due to the open nature of the internet, users face the danger of having their private information
intercepted or distorted while taking advantage of the convenient electronic information exchange made
possible by highly evolved internet and information technology. Thus, it is crucial to create secure
communication methods [1]. The most important methods for information security are ciphering and
information hiding [2]. Ciphering is a method for encoding and manipulating private data so that only
authorized users may access or use it [3]. The science of information hiding is called steganography [4]. It is
done by obscuring the existence of the information by blending it into other data [5]. A variety of digital
mediums, such as image, video, audio, and text, can be utilized to conceal sensitive information [6], [7]. The
information hiding idea is illustrated in Figure 1.
The vast majority of currently used methods to conceal information rely on image hiding algorithm.
This method principally meets the imperceptibility criteria of hiding algorithm by making the little
modifications made to the image imperceptible to the human visual system. Some of the image hiding
algorithms used are spatial domain method, where the secret information is directly embedded in the pixel
intensity, such as least significant bit technique, and another method of the image hiding algorithms is
transform domain, where the secret information is concealed in the frequency domain of an earlier
transformed image [8].

 ISSN: 2088-8708
Int J Elec & Comp Eng, Vol. 13, No. 6, December 2023: 6797-6805
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Figure 1. Depicts the information hiding idea [9]
The major problem of data concealing strategies is to include the most information possible while
maintaining the image’s quality, security, and method resilience to electronic attacks by hackers. Due to the
vast number of available digital images on the web and the ease with which the images are used in a hiding
process, several schemes have been proposed to hide data in images. Researchers have made an effort to
create contemporary strategies to deal with the rapid evolution of hiding techniques [10].
Abdur et al. [11] described a hybrid security method that combines watermarking, steganography,
and encryption. It consists of three essential parts: firstly, the secret image is ciphered utilizing the secret key.
Secondly, the encrypted image embedded into the cover image utilizing the least significant bit (LSB)
method to obtain the stego-image. Thirdly, the ownership of the stego-image has been ensured by using
watermarking in spatial and frequency domains, respectively. Their suggested method offers great security
against threats and assaults. Lotlikar [12] proposed data hiding method-based cryptography algorithms. The
primary goal of their proposed method is to offer a safe means of sending and receiving sensitive and
significant data between users in the form of images.
Susanto et al. [13] proposed a method for combination two security techniques, steganography and
cryptography. The steganography technique is based on LSB that has benefits in data embedding capability
and secret data imperceptibility. Since the LSB approach is so straightforward and predictable, additional
encryption techniques are used to increase communication security. The secret data is encrypted using hybrid
Beaufort Vigenere (HBV) before embedding it. HBV encryption is a combination of Vigenère cipher and
Beaufort algorithm in order to increase data security.
Alabaichi et al. [14] proposed an image steganography utilizing LSB and secret map approaches
that performs by applying 3D Chebyshev and 3D logistic maps in order to achieve excellent security. The
proposed method is based on the idea of performing random embedding and choosing a pixel from the cover
image. The suggested approach is thoroughly assessed using a variety of metrics, including correlation
coefficient, homogeneity, information entropy, histogram, concealing capacity, key sensitivity, peak signal-
to-noise ratio (PSNR), mean square error (MSE), and image fidelity. As a result, their proposed method
effectively conceals sensitive information while maintaining a stego-image with high visual quality.
Almayyahi et al. [15] focused on creating a safe technique for concealing information in images
using LSB. The Huffman algorithm is used to compress the secret message before it is moved on to the
embedding step. Exclusive-NOR (XNOR) operation and the Fibonacci algorithm are then used to choose
which pixels to insert secret information. These procedures lead to the creation of a stego-image with two
secret keys. The evaluation step of their proposed method demonstrates both the rising security and
imperceptibility.
Almazaydeh [8] presented an image steganographic method utilizing a canny edge detector that
depends on embedding the private message bits using variable LSB length of one channel from the red,
green, and blue (RGB) cover image. The blue channel was chosen because a steganography-based study
revealed that blue color intensity is seen visually as being less distinct than red and green colors. Private bits
are hidden up to four LSB bits which are chosen using a random number generator.
Ogundokun and Abikoye [16] proposed a modified LSB approach capable of concealing and
preserving medical data in order to address the essential authentication problem. Their proposed method
employed a logical bit shift operation. Their suggested protected medical information system was shown to
be effective in concealing medical data and producing undetected stego-image.

Int J Elec & Comp Eng ISSN: 2088-8708 
Hiding algorithm based fused images and Caesar cipher with intelligent security … (Huda Hussein Abed)
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An image steganography technique-based Alpha blending is proposed in [17] by utilizing Haar
discrete wavelet transform (DWT). DWT is utilized for both the cover image and the secret image. The secret
image is ciphered first and then fused to create the stego-image.
Nezami et al. [18] suggested a method that employs the hash function for steganography, and the
Caesar cipher and Vigenère to encrypt the message before the hiding process. The proposed approach uses a
cover image in the spatial to hide encrypted data. Comparing the suggested method to the conventional LSB
steganography methodologies, security and speed are improved.
This paper introduces security procedures for confidential information by combining ciphering and
information hiding techniques. Confidential information is ciphered using Caesar cipher with an intelligent
method to generate Caesar key by deriving it from the length of confidential information according to a
mathematical equation. Thus, the Caesar key exchange between the two ends of the connection is not
required.
After that, a 1’s complement is taken for each character in the encoding data to provide a second
level of security, then the 1’s complementary form is hidden using an information hiding technique in the
spatial domain with intelligent methods for creating the medium of hiding technique. The hiding medium is
created by fusing two images, then scattering the resultant fused image by 1’s complement and circularly
shifting the bits of fused pixels with specified positions before the hiding process. Thus, the security of the
spatial domain pixels is reinforced.
The paper is categorized into the following categories: section 2 introduces the principle of Caesar
cipher and fused image. In section 3, details of the proposed algorithm are presented. In section 4, the
detailed results were summarized and discussed. Finally, section 5 is considered to be the conclusion of the
paper.
2. PRINCIPLE OF CAESAR CIPHER AND FUSED IMAGE
2.1. Caesar cipher
Caesar cipher is an example of a substitution cipher, where each letter in the plaintext is changed to
a letter that is moved a predetermined number of positions down the alphabet. Modular arithmetic is used to
illustrate the encryption [19], [20]. Julius Caesar, the invention’s name, is another name for the Caesar cipher
[19]. For instance, if the shift was 3, A would become D, B would become E, and C would become F [21] as
demonstrated in Figure 2.
One of the Caesar cipher’s biggest flaws is that, even in cipher-text only scenarios, it is readily
cracked. Various methods that break the text of the codes have been discovered utilizing frequency analysis
and pattern words. One method is to employ brute force in order to match the frequency distribution for the
letters. Because there are a finite number of shifts that might occur [22].
2.2. Fused images
Image fusion is the technique of taking the visually significant information from two or more
images and merging them together to create a single fused image [23]. It is crucial that the image fusion be
carried out without using any sort of final image distortion [24]. Figure 3 depicts the wavelet-based image
fusion algorithm. The source images are decomposed into approximate coefficient and detailed coefficient at
the necessary level utilizing DWT. The fusion rule is used to merge the approximate and detailed coefficients
of both source images. By using inverse discrete wavelet transform (IDWT), the fused image is produced
[25].
Figure 2. depicts the process of Caesar
cipher [21]
Figure 3. depicts the process of the fused image [25]

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3. METHOD
The different steps employed to provide security in the proposed method are demonstrated in detail
according to the following parts. Part 1 explains the detailed steps that are performed to reinforce the security
of the pixels in the spatial domain before the hiding process, while the detailed steps to enhance the security
of confidential data are explained in part 2. Finally, the entire proposed schemes at the sending and receiving
ends, respectively, are shown in Figures 4 and 5.
Figure 4. The steps employed for the sending part

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Figure 5. The steps employed for the receiving part
Part 1: the steps of the security procedure for creating the medium of hiding are explained as:
a) Fuse two cover images of the same size after reading them to create a fused image.
b) The positions of pixels for the fused image are shifted circularly by half its size in each dimension. Thus,
the location of the corners for the fused image is replaced.
c) The 1’s complements for each pixel of the fused image are obtained and saved as a complementary
image. After that, the bits per pixel are shifted by 3 locations to the left and saved as a shifted image.
Finally, an XOR operation is performed between the complementary image and the shifted image to
create a scrambled fused image with new pixel values used to hide secret bits.

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Part 2: the steps of the security procedure for confidential data before hiding are explained as:
a) After reading the secret text, it will be encrypted using Caesar cipher with a new method of formation the
Caesar key depending on the length of confidential data according to a mathematical equation.
b) The 1’s complement for each letter in the cipher data is obtained to provide a second level of security.
4. RESULTS AND DISCUSSION
The execution of the suggested algorithm is performed by using MATLAB (R2021a). Two
grayscale cover images of the same size are required to observe the achievement of the algorithm in offering
security for secret information. The database of the signal and image processing institute “SIPI image
database” is utilized for the examination. The steps employed for the proposed scheme at the sending part are
demonstrated with detailed in the following Figures. Figure 6 illustrates the steps employed for the process of
fusing two cover images, the first cover image in Figure 6(a), the first cover image after applying DWT in
Figure 6(b), the second cover image in Figure 6(c), the second cover image after applying DWT in
Figure 6(d), the process of fusing two cover images in frequency domain in Figure 6(e), and applying IDWT
for the fused images in Figure 6(f). Figure 7(a) illustrates the corner replacement of the fused images, 1’s
complement for the pixels in Figure 7(b) and scrambled fused images in Figure 7(c). Figure 8(a) illustrates
the secret information, cipher of secret information using the Caesar algorithm in Figure 8(b), and 1’s
complement of Caesar cipher in Figure 8(c). Figure 9 illustrates the steps employed for the formation of a
Ceasar key.
(a) (b) (c)
(d) (e) (f)
Figure 6. The steps employed for the process of fusing two cover images (a) 1st
cover image, (b) decomposed
1st
cover image using DWT, (c) 2nd
cover image, (d) decomposed 2nd
cover image using DWT, (e) fused two
cover images, and (f) fused images in special domain
As illustrated in Figures 6 and 7, several security steps are performed to reinforce the security of the
spatial domain pixels before the hiding process, so the attacker cannot know the pixel values utilized in the
hiding process. On the other hand, two security steps are implemented to enhance the security of confidential
data before the hiding process, as shown in Figures 8. In addition, the formation of the Caesar key based on
the number of characters for the secret data enhances the Caesar cipher secrecy, as the exchanging process of
the Caesar key between the sending and receiving parties is not required.
Table 1 shows the Caesar key for the different lengths of confidential data and the time required for
the encryption and decryption processes, respectively. According to the Caesar key shown in Table 1, the key

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is changed depending on the length of the confidential data, so it is possible to add data to the original secret
data to obtain a different key instead of exchanging a new key between the two ends of the connection.
(a) (b) (c)
Figure 7. The steps employed for enhancing the security of fused images (a) fused images with corner
replacement, (b) 1’s complement for the pixels, and (c) scrambled fused images
(b)
(c)
(a)
Figure 8. The steps employed for enhancing the security of secret information (a) secret information,
(b) cipher of secret information using Caesar algorithm, and (c) 1’s complement of Caesar cipher
Figure 9. The formation of Ceasar key
Table 1. The performance of the Caesar cipher with the formation of key
The number of characters Caesar key Time required for the encryption Time required for the decryption
278 characters 8 0.002117 seconds 0.000634 seconds
5. CONCLUSION
In this paper, a reliable algorithm for protecting confidential information utilizing fused images is
proposed, where four levels of security are provided for the secret information. Firstly, confidential
information is encrypted using Caesar cipher with a new method for the formation of the Caesar key. After
that, the cipher form of encrypted data is complemented using 1’s complement. That procedure enhances the
security of Caesar cipher and thus provides a second level of security for secret information. A third level for

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security is provided using fused two cover images, then scattering the resulting cover image by 1’s
complement and circularly shifting the bits of fused pixels with specified positions before the hiding process.
Finally, the fourth level of security is provided by the hiding technique in the spatial domain, where the
complemented form of cipher information is concealed in the scrambled fused image utilizing the LSB
technique. Simulation results demonstrate that the proposed approach provides higher security for
confidential information.
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BIOGRAPHIES OF AUTHORS
Huda Hussein Abed Assistant Lecturer at Communication Techniques
Engineering Department, Engineering Technical College-Najaf, AL-Furat Al-Awsat Technical
University. She received Bachelor’s and master’s degrees in Communication Techniques from
Engineering Technical College-Najaf, AL-Furat Al-Awsat Technical University, Iraq in 2010
and 2019, respectively. Her current research interests include communication security, digital
image processing, steganography, and digital communication. She can be contacted at email:
eng.huda2020@atu.edu.iq.
Aqeel Sajjad Shaeel works at Laser and Optoelectronics Tech. Eng. Department,
Engineering Technical College-Najaf, AL-Furat Al-Awsat Technical University. He received
the B.Sc. in Electrical Engineering from University of Babylon. He received a M.Sc. in
communication engineering from Amirkabir University of Technology. His research interests
include LEO Satellite, information security, IoT, digital communication. He can be contacted
at email: aqeelsajjad1@gmail.com.
Ruaa Shallal Abbas Annoze received her Bachelor of Communication Technical
Engineering from Engineering Technical Collage-Najaf, Iraq, in 2006, and her M.Tech. of
Communication System Engineering in the Department of Electronics and Communication
Engineering in SHIATS, Allahabad, India, in 2014. She is currently a Ph.D. student at Tabriz
university. Her area of interest includes digital signal processing, beam and channel estimation,
and Antennas Design. She can be contacted at email: coj.rua@atu.edu.iq.

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