| dc.description.abstract | The digital media has become more popular than the traditional analog media since it
witnessed a rapid decrease in the cost of processing, storage, and bandwidth. The digital data are easy to edit, modify and exploit. Therefore, it is convenient for people to transmit digital data and information through the internet. It is implied that information
can be modified easily by unauthorized people. The security and the validity in digital communication have therefore become main issues. Different technologies have been
developed to protect the digital data including cryptography and steganography.
Cryptography protects the data by converting them into meaningless information;
however, it gives an explicit indication about the protection process. Meanwhile, the
steganography schemes have been applied to avoid the hint of protecting the data by
hiding them in the cover data. In this project, the cryptography and steganography
schemes are combined to develop a hybrid security system that can provide a secure
communication between the sender and the receiver. This system uses the digital image
as a carrier medium to embed the ciphered secret image. Firstly, the secret grayscale
image is encrypted by using a popular encryption algorithm called Advance Encryption
Standard (AES). Then, the encrypted image is hidden in a cover image (i.e., colour or
grayscale) using steganography technique based on the Patch Reference Table Pixel
Value Difference (PRT-PVD), which called APP. The APP is evaluated in terms of
Peak Signal to Noise Ratio (PSNR), embedding capacity, and the ability to resist the
steganalysis attach such as the histogram difference. The experimental results indicated
that the proposed approach APP provided stego-images with a good perceptual quality;
this was indicated by the obtained high PSNR values in comparison with the PVD, MFPVD,
AES-PVD, and AES –LSB techniques. Apart from that, the difference histograms
of the cover images and the stego-images are very minimal. For 128×128 grayscale
cover images and payload of 20000 bits, the APP achieved an average value of PSNR
of 48.7230 dB, while the average PSNR values of PVD, MF-PVD, AES-PVD, AESLSB
and PRT-PVD techniques are 42.3399, 43.8579, 42.3639, 47.2249, 48.3877 dB,
respectively. Moreover, the APP provides a higher PSNR for all experiments of
different cover image (i.e., colour or grayscale) types and sizes (225×225, 512×512)
with different payloads. In addition to improvement in performance, this study
suggested a method that can automatically calculate the optimal threshold value for the
APP system. As a result, using the proposed approach can improve the security of data
transmission through the open channels. | en_US |
