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<article xmlns:xlink="http://www.w3.org/1999/xlink">
  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Image Steganography Method using LSB and AES Encryption Algorithm⋆</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Tamara Radivilova</string-name>
          <email>tamara.radivilova@nure.ua</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Ihor Dobrynin</string-name>
          <email>ihor.dobrynin@nure.ua</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Arkadii Snihurov</string-name>
          <email>arkadii.snihurov@nure.ua</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Svitlana Stanhei</string-name>
          <email>svitlana.shtanhei@nure.ua</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Serhii Bulba</string-name>
          <email>s.bulba@knute.edu.ua</email>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Kharkiv National University of Radio Electronics</institution>
          ,
          <addr-line>14 Nauky ave., 61166 Kharkiv</addr-line>
          ,
          <country country="UA">Ukraine</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>State University of Trade and Economics</institution>
          ,
          <addr-line>19 Kyoto str., 02156 Kyiv</addr-line>
          ,
          <country country="UA">Ukraine</country>
        </aff>
      </contrib-group>
      <fpage>32</fpage>
      <lpage>44</lpage>
      <abstract>
        <p>In today's world, data security is a key issue in many industries. Cryptography ensures data confidentiality, while steganography is used to conceal information transmitted over unsecured communication channels. This paper proposes methods based on a combination of the fast LSB steganography algorithm and the AES symmetric encryption algorithm to protect images. The proposed methods include shifting from the beginning of the container to increase the security of encrypted data and protect against image cropping. Also, algorithms are proposed to increase the amount of information transmitted with data recording in the last 2 bits of the blue pixel channel and data recording in each pixel channel in the last bit. The following concealment indicators were used for the analysis: Peak Signal-toNoise Ratio (PSNR), Structural Similarity Index Measure (SSIM), and Normalized Cross-Correlation (NCC). The study yielded results suggesting that the fastest algorithm for steganography and encryption is a modification with the insertion of two characters into the last bit of the blue pixel channel (LSB+AESos+2bit). The slowest algorithm is the modification using AES encryption and a shift from the beginning of the steganocontainer (LSB+AES-os). In the case of decoding, modifications using AES encryption and a change from the start of the steganographic container (LSB+AES-os) show almost identical results and are the fastest when decoding messages. The slowest algorithm is the one with message embedding in all three channels in the last bit (LSB+AES-os+3ch), but it should be noted that it is the most complex and includes all other modifications of the LSB algorithm. Increasing the amount of data embedded in the container negatively affects the display statistics. Still, this effect does not reduce the metrics of standard indicators, which are sufficient for steganography. The number of bits suitable for embedding depends on the source file and linearly on the number of LSB bits used for encoding. The number of bits ideal for encoding also depends on the shift percentage. The message embedding is not visually noticeable when using any developed methods. Experimental results demonstrate that the proposed algorithms effectively protect data with a high peak signal-to-noise ratio (PSNR) and low mean square error (MSE), ensuring high image quality and reliable encryption and decryption of information. Depending on the reliability requirements of the steganographic system, the presented methods can be varied, thereby changing the maximum amount of hidden information.</p>
      </abstract>
      <kwd-group>
        <kwd>eol&gt;AES</kwd>
        <kwd>LSB</kwd>
        <kwd>steganography</kwd>
        <kwd>encryption</kwd>
        <kwd>decryption</kwd>
        <kwd>peak signal-to-noise ratio</kwd>
        <kwd>structural similarity index measure</kwd>
        <kwd>normalised cross-correlation</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>1. Introduction</title>
      <p>A comprehensive modern information security system cannot be implemented using only one
information security method [1, 2]. Ensuring data confidentiality is a pressing issue, as there are
many attacks aimed at violating data confidentiality [3–5]. Therefore, scientists and professionals
are developing new and improving existing methods for ensuring data confidentiality and
information security [6–8].</p>
      <p>Modern steganography hides the fact that data is being transferred by using a masking
algorithm that modifies a specific array of open data, adding a confidential message to it. There are
many methods and techniques of steganography, varying in computational complexity, capacity,
and targeting different data formats. Today, steganography is used for covert communication,
image copyright protection (authentication), fingerprinting (intruder tracking), adding captions to
images, adding additional information such as subtitles to videos, protecting image integrity
(detecting fraud), copy control in DVD recording and smart browsers, and automatically providing
copyright information [9–11].</p>
      <p>In cryptography, mathematical transformations are used to ensure data confidentiality, thanks
to which data takes on a confused form [12, 13]. In steganography, secret messages are embedded
in images or multimedia files during their invisible transmission via open communication channels
[14]. Steganography hides confidential data and the connection between the sender and the
recipient, while cryptography hides confidential data and identifies the sender and recipient [15,
16]. An effective and one of the most popular approaches is to combine cryptographic and
steganographic methods to protect information from unauthorized access [17, 18].</p>
      <p>The synergistic combination of AES encryption and LSB steganography provides a powerful
two-layer security mechanism [18]. In this hybrid approach, secret data is first encrypted using a
reliable AES algorithm, which guarantees its confidentiality even if detected. This encrypted data is
then hidden in an image using the LSB steganography method, concealing its existence [19]. This
combined strategy significantly increases the overall security, confidentiality, and integrity of the
transmitted information, making it resistant to detection and decryption by unauthorized persons.</p>
      <p>Recent research and publications analysis. Recent research indicates a significant interest
in combining steganography and cryptography [20, 21]. Many scientific works are devoted to
combining the AES cryptographic method and the LSB steganographic method [22], as they are the
fastest and have a low level of distortion. However, further research has consistently introduced
additional levels of complexity and complementary techniques. This includes using compression
algorithms such as Deflate or Discrete Wavelet Transform (DWT) to reduce the size of the secret
message, thereby increasing the efficiency or capacity of embedding [12, 23]. In addition,
randomization techniques such as random pixel selection and random shuffling are widely used to
make embedding locations less predictable, significantly improving protection against statistical
steganalysis [23–26]. In [27], the authors propose a combination of LSB and RSA and Caesar
encryption. However, these methods do not allow changing the amount of confidential information
embedded.</p>
      <p>In [28], the primary methodology involves embedding LSB in combination with AES encryption.
Options for integrating RSA with LSB and AES are also explored, and these hybrid approaches are
compared with the Pixel Locator Sequence (PLS) method. In [29], the authors proposed a technique
that uses LSB matching for data embedding, and in the previous stage, AES encryption is used to
provide a two-layer security architecture. The novelty lies in using mosaic images as a cover
medium, which inherently supports higher embedding capabilities and reduces visual distortion.
However, the operating time of these systems is quite long.</p>
      <p>The approach developed by the authors [30] involves encrypting the target image using AES
and then hiding the target text data inside the encrypted AES image using the LSB method, further
enhancing data security and potentially simplifying key management by eliminating the need for
direct key exchange. However, the amount of embedded information is reduced, and the processing
time of this approach is quite long.</p>
      <p>Integrating error correction codes like Reed-Solomon demonstrates a desire to ensure message
recovery even if the steganographic image data is damaged during transmission or storage [ 25].
The methodology proposed by the authors includes Fernet encryption (AES-128 CBC),
ReedSolomon encoding for error correction, and LSB steganography for embedding. This multifaceted
approach aims to improve security and robustness and achieves a high data payload of 3 bits per
pixel for RGB images without noticeable distortion. However, the runtime of this system is quite
long.</p>
      <p>Thus, there is a pressing need to develop steganography and encryption methods with the
ability to select a process depending on the amount of information to be hidden and the reliability
requirements of the steganographic system.</p>
      <p>The purpose of the paper. This work aims to develop and analyze data hiding methods based
on steganographic and cryptographic encryption algorithms to ensure data confidentiality and
integrity. To achieve this goal, the following tasks need to be solved:
1. Develop secure and effective methods for hiding confidential data in images with minimal
changes to the quality of the steganographic images.
2. Develop solutions for encrypting hidden messages using the Advanced Encryption System
(AES) and integrate it with Least Significant Bits (LSB) steganography to protect the
content of secret messages from disclosure.
3. Ensure data integrity and confidentiality by preventing unauthorized access.
4. Minimize visual distortions in the steganographic image while maximizing embeddability.
5. Make the steganographic process resistant to visual attacks that could lead to the detection
of hidden messages.</p>
      <p>These tasks aim to create methods of steganographic information protection to select one of
them depending on the amount of information to be hidden and the reliability requirements of the
steganographic system.</p>
    </sec>
    <sec id="sec-2">
      <title>2. Methodology</title>
      <p>2.1.</p>
      <sec id="sec-2-1">
        <title>Least significant bit replacement method</title>
        <p>A set of characteristics is used to analyze and subsequently select steganographic algorithms [ 31],
including:</p>
        <p>• Bandwidth is the number of bits of the hidden message that can be transmitted using this
method in an image of a fixed size.</p>
        <p>• Robustness is the ability to extract hidden information after general image processing
operations: linear and non-linear filters, lossy compression, contrast adjustment, recoloring,
resampling, scaling, rotation, noise addition, cropping, printing/copying/scanning, pixel
rearrangement in a small neighborhood, color quantization, etc.</p>
        <p>• Invisibility is perceptual transparency, a concept based on the properties of the human
visual or auditory systems.</p>
        <p>• Security is embedded information that cannot be removed by targeted attacks based on a
known embedding and extraction algorithm and knowledge of at least one medium with a hidden
message.</p>
        <p>• The complexity of embedding and detection is the number of standard operations that will
be performed to embed and detect a hidden message.</p>
        <p>According to most of the above characteristics, the Least Significant Bits (LSB) replacement
method is the most common among replacement methods in the spatial domain. The general
principle of these methods is to replace the redundancy, the insignificant part of the image, with
bits of the secret message, i.e., to hide information by replacing the last bits of the image that
encode color with bits of the hidden message [22]. The principle of information hiding is to convert
text into a byte sequence. The difference between empty and filled containers should not be
noticeable to human vision and entropy analysis systems. To extract the message, you must know
the algorithm to place the hidden information in the container. The popularity of this method is
due to its simplicity and the fact that it allows you to hide relatively large amounts of information
in relatively small files. The NZB method has low steganographic resistance to passive and active
attacks. Its primary disadvantage is its high sensitivity to the slightest changes in the container.
Noise-resistant encoding is often used to reduce this sensitivity.</p>
        <p>In BMP format, an image is stored as a matrix of color values, with an image stored for each
point. If each component of the RGB space (also called color channels) is stored in one byte, it can
take values from 0 to 255 inclusive, corresponding to 24-bit color depth. The peculiarity of human
vision is that it poorly distinguishes between slight color variations. For 24-bit color, a change in
each of the three channels of the least significant bit (i.e., the rightmost bit) results in a change of
less than 1% in the intensity of a given point, allowing them to be changed imperceptibly to the eye
at will.</p>
        <p>Let’s calculate the throughput of the method. Suppose we discard the service information at the
beginning of the file, which is insignificant in relation to the image size. In that case, we can
transmit a message that is 1/8 the size of the container or 1/4 the size of the container (when using
the last 2 bits in bytes, respectively).</p>
        <p>The principle of the LSB steganographic method is as follows.</p>
        <p>Let there be a 24-bit grayscale image. Each pixel is encoded with 3 bytes containing the RGB
channel values. By changing the least significant bit, we change the value of the byte to one. Such
gradations are invisible to the human eye and may not be displayed at all when using low-quality
output devices.</p>
        <p>The example below (Fig. 1) shows how a message can be hidden in the first eight bytes
corresponding to three pixels in a 24-bit image.</p>
        <p>In the example, only the three bits that were changed are highlighted. Using the LSB
steganographic method requires, on average, that only half of the bits in the container image be
changed.</p>
        <p>A slight modification of this steganographic technique allows two or more of the least
significant bits per byte to be used to embed a message. This increases the amount of hidden
information in the container object, but the concealment is significantly reduced, making it easier
to detect the steganography. Other variations of this method include levelling statistical changes in
the image. Some intelligent software for detecting steganography checks areas with a single solid
color. Modifications to these pixels should be avoided to improve concealment.</p>
        <p>To improve the performance of the LSB steganography algorithm, the following should be done:
• Throughput is developing an algorithm with double and triple capacity relative to standard
performance indicators.</p>
        <p>• Invisibility is developing a distortion analyzer to select the best algorithm.</p>
        <p>• Security integrates the Advanced Encryption System (AES) symmetric information
encryption module.</p>
        <p>• The algorithm modifies detection complexity to scramble unused image space in the
invisible spectrum.</p>
        <p>Let us consider modifications of the LSB steganographic algorithm.</p>
        <p>To ensure the security of the LSB steganographic algorithm, we will add an algorithm for
encrypting embedded messages using the AES encryption algorithm, the general scheme of which
is shown in Fig. 2.</p>
        <p>The AES algorithm, or Rijndael, is a symmetric block cipher that encrypts messages in 128-bit
blocks and uses a 128/192/256-bit key.</p>
        <p>Encryption with a secret key is used to maintain data confidentiality. This method can be used
for authentication and data integrity. The work uses an encryption algorithm with a key length of
256 bits.</p>
        <p>Not only was AES encoding used, but there was also a change in the message end search
algorithm. Previously, it was searched “on the fly” in the bitwise decoding cycle itself. Still, here, all
the last bits of the blue channel of the entire image are taken, and only then is the message length
determined using a binary search in the whole line where the marker occurs.</p>
        <p>Modification with message offset. Shifting the message from the beginning of the
stegaconteiner protects the latter from truncation attacks. Also, the algorithm assumes that the
decoding side does not know the shift percentage; the algorithm determines the encrypted
message’s beginning and end. At the start of the algorithm, an image, a key, and the shift value
from the beginning of the container in percent are obtained; then the width and length of the
image are determined, which are multiplied, and the shift percentage is taken; the length of the
message to be encrypted by the AES algorithm is taken.</p>
        <p>Modification of information encoding in the last 2 bits of the blue channel. A slight
modification of this steganographic method allows two or more lower bits per byte to be used for
embedding messages. The pixel index is taken, and from it, the blue channel index is converted to a
binary string and then to a binary array; the last two bits are replaced with 2 bits from the message
string, and then the algorithm is followed. This allows twice as much information to be embedded
in the channel that is least noticeable to the human eye.</p>
        <p>In the modification with encoding of information in the last bit of each RGB channel,
the same is done as in the previous modification with encoding of information in the last 2 bits of
the blue channel, not only for the blue channel, but for each RGB channel, one bit. In this
modification, AES encoding and message shift from the beginning of the steganographic container
were used, and embedding was performed in the last bit of the message in all pixel channels. This
allows embedding three times more information.</p>
        <p>Thus, the work implements and analyzes the LSB steganographic algorithm and its subsequent
modifications: LSB is simple implementation of the LSB algorithm; LSB+AES is modification of LSB
using AES encryption; LSB+AES-os is modification of LSB using AES encryption and shifting from
the beginning of the steganographic container; LSB+AES-os+2bit is modification of LSB using AES
encryption, shifting from the beginning of the steganographic container, and recording data in the
last two bits of the blue pixel channel; LSB+AES-os+3ch is modification of LSB using AES
encryption and shifting from the beginning of the steganographic container and writing data to
each pixel channel in the last bit.
2.2.</p>
      </sec>
      <sec id="sec-2-2">
        <title>Evaluation of the quality of the steganographic system</title>
        <p>Creating and operating a reliable steganographic method requires specific tools for its control and
evaluation. Quantitative assessment of the resistance of a steganographic protection system to
external influences is a rather complex task, which is usually implemented in practice by methods
of system analysis, mathematical modelling, or experimental research.</p>
        <p>As a rule, a professionally designed steganographic system provides a three-level model of
information protection, solving two main tasks:
1. Concealing the very fact of the existence of protected information (first level of
protection).
2. Blocking unauthorized access to information by selecting an appropriate method of
information concealment (second level of protection).</p>
        <p>Finally, it is necessary to take into account the possibility of a third level is preliminary
cryptographic protection (encryption) of the concealed information.</p>
        <p>The quality of the main characteristic of a steganographic system is the level of concealment is
assessed by conducting analytical studies (steganographic analysis) and field tests.</p>
        <p>Most distortion indicators or quality criteria belong to the group of differential distortion
indicators. These indicators are based on the difference between the original container (undistorted
signal) and the result container (distorted signal). The second group includes indicators based on
the correlation between the original and distorted signals (so-called correlation distortion
indicators).</p>
        <p>To conduct a comparative analysis of steganographic algorithms, a software solution was
developed that compares images based on quality indicators: Peak Signal-to-Noise Ratio (PSNR),
Structural Similarity Index Measure (SSIM), and Normalized Cross-Correlation (NCC) [31].</p>
        <p>The formula for calculating the Peak Signal-to-Noise Ratio (PSNR) is as follows:</p>
        <p>SSIM ( c , s )=[l ( o , p ) ]α⋅[c ( o , p ) ]β⋅[s ( o , p ) ]γ ,
MSE =</p>
        <p>1 m∑−1 n∑−1 [ C ( x , y )−S ( x , y ) ]2 ,
m⋅n i=0 j =0
where MSE is the mean squared error between the original and modified images (stegoimage).
MAXI is the maximum possible pixel brightness (intensity) (for 8-bit images, MAXI = 255, and for
10-bit images, MAXI = 1023:
where m is the number of rows (height) of the image; n is the number of columns (width) of the
image; C(x,y) is the pixel value in the original image at coordinates (x,y); S(x,y) is the pixel value in
the modified image at coordinates (x,y).</p>
        <p>A high PSNR value indicates that the modified image is very similar to the original, i.e., the
“noise” (changes) level is low.</p>
        <p>The Structural Similarity Index Measure (SSIM) is more complex than PSNR because it considers
three key components that correspond to the characteristics of human vision: brightness, contrast,
and structure.</p>
        <p>
          The SSIM index for two images (or windows) o and p is calculated as the product of three
components:
(
          <xref ref-type="bibr" rid="ref1">1</xref>
          )
(
          <xref ref-type="bibr" rid="ref2">2</xref>
          )
(
          <xref ref-type="bibr" rid="ref3">3</xref>
          )
where l ( o , p )= 2 2μo μ p +const 1 is the luminance component, μo and μp are the average pixel
μo + μ2p +const 1
intensity values in windows o and p; c ( o , p )= 2 σ2 o σ p +const 2 is the contrast component, σo and σp
σ o +σ 2p +const 2
are the standard deviations of pixel intensity (contrast measurement) in windows o and p;
s ( o , p )= σ op +const 3 is structure component, σop is covariance between pixels in windows o and
σ o σ p +const 3
p (structural similarity measurement); α, β, and γ are coefficients determining the importance of
each element (usually their values are equal to 1); const1, const2, and const3 are small constants
added to avoid division by zero when the denominators are close to zero. Their values are
calculated using the formulas const1 = (K1,MAXI)2 and const2 = (K2,MAXI)2, where K1 and K2 are
constants (usually K1 = 0.01, K2 = 0.03).
        </p>
        <p>Normalised Cross-Correlation (NCC) is a metric used in steganography to assess the
similarity between two images. In steganography, NCC helps determine how similar a
steganographic image (with hidden data) is to the original container image. Unlike PSNR or MSE,
which focus on pixel-by-pixel differences, NCC measures the degree of linear dependence between
two images.</p>
        <p>
          The formula for NCC is as follows:
m−1 n−1
∑ ∑ ( C ( x , y )−C ) ( S ( x , y )−S )
NCC = x =0 y =0 , (
          <xref ref-type="bibr" rid="ref4">4</xref>
          )
√m∑−1 n∑−1 ( C ( x , y )−C )2 m∑−1 n∑−1 ( S ( x , y )−S )2
        </p>
        <p>x =0 y =0 x =0 y =0
where C(x,y) is the pixel value in the original image; S(x,y) is the pixel value in the steganographic
image; C and S are the average pixel intensity values in the original and steganographic images,
respectively; m and n are the image dimensions (height and width).</p>
        <p>The NCC value ranges from –1 to +1. An NCC value close to 1 indicates a very high similarity
between images. This means the steganographic image has an almost identical structure and pixel
intensity distribution to the original. A high NCC value (e.g., above 0.99) is a positive indicator for
a steganographic algorithm, as it demonstrates that the embedding of data has not significantly
altered the overall structure of the image, making the hidden data difficult to detect.</p>
        <p>Generalized analysis algorithm:
1. Obtaining the original image and container images, recognizing the extension, and
converting to a pixel array.
2. Comparing each container with the original, obtaining coefficients for each value of the
number of embedded bits for each distortion indicator.
3. Determining the maximum and minimum values of the coefficients for each distortion
indicator.
4. Forming a data array and constructing a graph.</p>
        <p>Limitations on the use of the developed approach:
1. The message should not exceed 1/8 of the image file size; otherwise, the text will be
shortened to the maximum possible size. When specifying the offset from the beginning of
the container, subtract this percentage from the message accordingly; otherwise, the
message will also be forcibly shortened.
2. For embedding, a BMP format container is recommended.
3. The container should allocate 8 bits per pixel.</p>
      </sec>
    </sec>
    <sec id="sec-3">
      <title>3. Analysis of the effectiveness of the steganography system</title>
      <p>3.1.</p>
      <sec id="sec-3-1">
        <title>Experimental part</title>
        <p>The purpose of the experiments was to analyze the effectiveness of the image in terms of data
hiding. The data set for transmitting the secret message consisted of a text file (.txt). The
experiment was conducted on a computer with an Intel(R) Core(TM) i9-13900HX processor with a
clock speed of 5.40 GHz, 32.0 GB of RAM, and a 64-bit Windows 11 operating system.</p>
        <p>The work implements and analyzes the LSB steganographic algorithm and its subsequent
modifications, which are listed above:
1. LSB is a simple implementation of the LSB algorithm.
2. LSB+AES is a modification of LSB using AES encryption.</p>
        <p>3. LSB+AES-os is a modification of LSB using AES encryption and shifting from the beginning
of the steganographic container.</p>
        <p>4. LSB+AES-os+2bit is a modification of LSB using AES encryption and shifting from the
beginning of the steganographic container and writing data to the last 2 bits of the blue pixel
channel.</p>
        <p>5. LSB+AES-os+3ch is a modification of LSB using AES encryption, shifting from the beginning
of the steganographic container and recording data in each pixel channel in the last bit.</p>
        <p>The paper developed software for implementing steganographic algorithms based on the LSB
method and analyzed their effectiveness. For this purpose, the image shown in Fig. 3 was taken,
and the steganographic methods were analyzed.</p>
      </sec>
      <sec id="sec-3-2">
        <title>Analysis of the effectiveness of the steganographic system based on performance indicators</title>
        <p>Analysis by speed. The proposed algorithms’ speed data about the encrypted message’s capacity
are shown graphically in Fig. 4.</p>
        <p>Based on the results obtained, we can conclude that the fastest algorithm for steganography is a
modification with the insertion of two characters into the last bit of the blue channel of the pixel
(LSB+AES-os+2bit). The slowest modifications are those using AES encryption and shifting from
the beginning of the steganocanister (LSB+AES-os). The algorithm’s speed-to-decoding ratio is
shown in Fig. 5.</p>
        <p>The analysis results show that in the case of decoding, almost identical results are obtained by
the following modifications with AES encryption and with a shift from the beginning of the
steganographic container (LSB+AES-os), which are the fastest in decoding messages. The slowest
algorithm is the one with the message embedded in all three channels in the last bit
(LSB+AESos+3ch), but it should be noted that it is the most complex and includes all other modifications of
the LSB algorithm.</p>
        <p>Analysis by distortion indicators. To understand the extent of distortion introduced into an
image, it is necessary to compare metrics for different amounts of embedded data. The study was
conducted on the same image with a size of 29 kilobytes. Various percentage values of character
capacity relative to a simple implementation of the LSB algorithm were taken as typical data sizes
for embedding, i.e., 25617 characters were taken as 100%.</p>
        <p>The summary results for each steganography system quality assessment indicator and the level
of concealment are given in Tables 1, 2, and 3.</p>
        <p>Based on the results obtained, we can conclude that the best quality indicators are achieved by
algorithms where information encoding took place in the last bit of the blue channel, i.e., the
original algorithm embedded in the last bit, a modification using AES encryption with embedding
in the last pixel bit, and a modification with a shift based on the least significant bit. Accordingly,
embedding in the last bits of the three pixel channels shows the algorithm’s worst performance.
Increasing the amount of data embedded in the container negatively affects the display statistics.
Still, this effect does not reduce the metrics of standard indicators, which are sufficient for
steganography.</p>
        <p>The normalized average absolute difference, which indicates the degree of difference between
the original container and the container with the embedded secret file, predictably increases with
the length of the message, but the increase is not significant. The image quality deviates from 1 by
an average of 0.02%. Visually, container changes cannot be detected in any algorithm modification,
and even mathematical analysis does not show a significant distortion value.</p>
      </sec>
    </sec>
    <sec id="sec-4">
      <title>Conclusions</title>
      <p>In the course of this work, an analysis of steganographic methods based on LSB was proposed and
carried out. The following concealment indicators were used for the analysis: Peak Signal-to-Noise
Ratio (PSNR), Structural Similarity Index Measure (SSIM), and Normalized Cross-Correlation
(NCC). The study yielded results suggesting that the fastest algorithm for steganography is a
modification involving the insertion of two characters into the last bit of the blue channel of a pixel
(LSB+AES-os+2bit). The slowest algorithm is the modification using AES encryption and a shift
from the beginning of the stegacontainer (LSB+AES-os). In the case of decoding, modifications
using AES encryption and a change from the start of the steganographic container (LSB+AES-os)
show almost identical results and are the fastest when decoding messages. The slowest algorithm is
the one with message embedding in all three channels in the last bit (LSB+AES-os+3ch), but it
should be noted that it is the most complex and includes all other modifications of the LSB
algorithm. Increasing the amount of data embedded in the container negatively affects the display
statistics. Still, this effect does not reduce the metrics of standard indicators, which are sufficient
for steganography.</p>
      <p>Depending on the reliability requirements of the steganographic system, the methods presented
can be varied, thereby changing the maximum amount of hidden information. The number of bits
suitable for embedding depends on the source file and linearly on the number of LSB bits used for
encoding. The number of bits ideal for encoding also depends on the percentage of shift. The
message embedding is not visually noticeable when using any developed methods.</p>
      <p>The practical significance of the results obtained lies in their potential application for covert
information transfer with high reliability and resistance to visual detection in open communication
channels. Further development of steganographic systems may include fractal analysis and wavelet
analysis, as well as the development of a framework for selecting the best steganographic
algorithm based on various quality indicators.</p>
      <p>
        Declaration on Generative AI
While preparing this work, the authors used the AI programs Grammarly Pro to correct text
grammar and Strike Plagiarism to search for possible plagiarism. After using this tool, the authors
reviewed and edited the content as needed and took full responsibility for the publication’s content.
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