Abstract :
The last few decades have been marked by a rapid growth and significant
enhancement of the internet infrastructures, i.e., the internet has become a broad network
enabling many enterprises around the world to interact while sharing multimedia data.
Nevertheless, this technology has brought many challenges related to securing private
and sensitive information which has led to the application of cryptography technique as
a mean for securing data by encrypting them. However, since the encrypted data can be
seen by active and sophisticated intruders during the transmission, this may lead to its
suspicion which can result in unauthorized access. Thereby, data hiding (which is also
called information hiding) is another technique for securing commutation via the public
network. Data hiding is one of the best and most challenging fields dealing with securing
organizational sensitive information due to many factors such as identity theft,
information phishing, user privacy, network policy violation, contents and copyright
protection. It is performed by utilizing some carriers to conceal private information which
is further extracted later to verify and validate the genuineness.
Digital steganography has been recognized among the recent and most popular data
hiding techniques. Steganography is the practice of concealing confidential information
in the codes that make up the digital files. Such digital files can be an image, audio, video,
and text. Different from cryptography, however, steganography provides security by
disguising the presence of communication. It originates from the concept that if the
communication is visible, the suspicion or attack is obvious. Hence, the main goal is to
always disguise the presence of the hidden confidential data. Recently, various data
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hiding methods based on digital image steganography have been already suggested by
several researchers around the globe. The main goal was to improve the security,
embedding capacity and the quality of the stego image. However, research have shown
that there is still a challenge to achieve a good visual quality of the stego media while
preserving a good embedding capacity. In this direction, this study aims at proposing a
new data hiding approach that enhances the quality of the stego image and the embedding
capacity. That is, the suggested approach enhances the existing data hiding methods by
utilizing pixel block, constant base point for each pixel block and the reduced difference
expansion scheme (RDE-scheme) for grayscale digital images.
Accordingly, the suggested enhancement is detailed as follows. First, the existing
reduced difference expansion scheme (RDE-scheme) for reducing the difference values
is enhanced in order to get possible small values to be used while concealing the secret
data into the cover image. The main objective behind this enhancement is to allow data
to be concealed while preserving the quality of the stego image. Notice that the suggested
RDE-scheme does not only enhance the quality but also it solves the problem of
underflow and overflow. The underflow is encountered when the pixel value in the stego
image is below 0 (Pixel value < 0) while the overflow occurs when it is greater than
255 (Pixel value > 255). Second, the new constant base point for each pixel block is
chosen differently for the sake of increasing the visual quality of the stego image. Third,
we have adjusted the size of the pixel block which achieves a high embedding capacity
while distorting the cover media from quad of quad (4 × 4 ) to quad, block of size 2 by 2
(2 × 2). Besides, the effect of varying the size of the secret data with respect to the quality
of the stego image is also investigated throughout this study.
Overall, based on the experimental results, good visual quality of the stego image
which is evaluated by measuring the peak signal-to-noise ratio (PSNR) and good
embedding capacity (measured in bits) are yielded compared to the previous approach,
i.e., the proposed method is effective in terms of maintaining both visual quality of the
stego image and the embedding capacity.
Index terms— Data hiding, information security, reduced difference expansion, digital
steganography, cover image, stego image, confidential data
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Beberapa dekade terakhir internet telah menjadi jaringan luas yang
memungkinkan banyak perusahaan di seluruh dunia untuk berinteraksi sambil berbagi
data multimedia. Ini merupakan tanda bahwa infrastruktur internet telah tumbuh dan
berkembang secara signifikan. Namun, teknologi ini memiliki banyak tantangan dalam
hal pengamanan informasi yang bersifat sensitif dan pribadi sehingga mendorong
penerapan teknik kriptografi untuk mengamankan data dengan cara mengenkripsinya.
Teknik kriptografi memiliki kekurangan yaitu hasil enkripsi dapat dilihat oleh penyusup
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