الفهرس 
CHAPTER (1) INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Transmission of images and videos in different communication systems is
a very important topic that attracted the attention of researchers in the last few
decades. The endeavor towards an optimum encryption scheme and an
optimum modulation method for this purpose is still under consideration.
Orthogonal frequency division multiplexing (OFDM) is an attractive
multicarrier transmission technique for wideband communications, because it
effectively transforms the frequency selective fading channel into a flat fading
channel. Hence, OFDM provides greater immunity to multipath fading and
impulsive noise and eliminates the need for complicated equalizers. However,
OFDM communication systems suffer from fading effects, high sensitivity to
carrier frequency offsets and phase noise.
In this thesis, we present a study for two different families of encryption
schemes; permutation-based schemes and diffusion-based schemes. The
objective of this study is to select the more suitable scheme for encrypted
image transmission over communication systems. Encryption and decryption
quality metrics are used in the presented comparison. Two modifications are
presented in this thesis in the permutation and diffusion algorithms to enhance
their properties. In the proposed hybrid encryption framework, we need to
achieve both diffusion and permutation in the encrypted Three-Dimensional
(3D) images. Towards this target, we used chaotic, Ron’s Code (RC6) or
Advanced Encryption Standard (AES) technique in a pre-processing step to
achieve the permutation and diffusion. The Rubik’s cube is used afterwards to
achieve more degree of permutation. Then we studied its sensitivity to the
wireless channel impairments, and the effect of channel equalization on the
received 3D images quality.