الفهرس 
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Abstract
The thesis presents a brief overview on the information security using chaotic maps, some of the chaotic maps systems, and some of the previous related algorithms which are based on chaotic maps systems; where the thesis focuses on two algorithms which are referred to here as SHCH, and HuXia.
The thesis presents a proposed encryption scheme based on Henon chaotic system (PESH) to secure the grayscale images by changing the values of the image pixels, where we use the quadratic function f(x)=x(2x+1) mod 256, which achieves quality and force in security, because the use of multiplication with addition and mod function greatly increases the diffusion achieved per round. The PESH algorithm encrypts the grayscale images with different modes of operations; such as ECB, CBC, CFB, and OFB. Results of the analysis and comparative performance evaluation show that the proposed algorithm PESH is the best and has a high strength in the security compared with SHCH algorithm.
The thesis presents a proposed permutation scheme based on a 3-D chaotic map system (PPS3DCS) to secure the colored images. The 3-D chaotic map system is Chen’s chaotic system. The PPS3DCS scheme is applied on three different images in the color frequencies. Several experimental measurements are applied on all encrypted images, whereas the results show that the proposed permutation scheme PPS3DCS is a good and an effective algorithm to secure the colored images by using the confusion process.
The thesis presents a proposed cryptosystem algorithm based on the combination of 2-D and 3-D chaotic maps systems (PCACH) to encrypt the colored images. Henon chaotic system is the 2-D chaotic map system, while Chen’s chaotic system is the 3-D chaotic map system. The PCACH algorithm contains confusion(permutation) algorithm is PPS3DCS, and the other is diffusion(substitution) algorithm which based on mixing between Henon system and Chen’s system. PCACH is applied on three different images in color frequencies with three different modes of operations, such as ECB, CBC, and OFB. The results of all experimental measurements show that, the PCACH algorithm is a good and secure procedure for encrypting the colored images.
Finally, the thesis presents an encryption quality measurement of PCACH algorithm for the colored images compared with another convergent algorithm HuXia. These two algorithms are applied on three images of different color frequencies with two different types of encryption modes, ECB and CBC. To assess the quality of encryption, some measuring factors are considered to evaluate the quality. For judging the force of security, we measure the plain-image sensitivity by using number of pixels change rate (NPCR) analysis and unified average changing intensity (UACI) analysis, measuring information entropy, and measuring the key sensitivity. Also, the encryption/decryption time and the throughput are measured for the two algorithms. The results show that, the PCACH algorithm is better than the HuXia algorithm, because PCACH algorithm has high quality of encryption, strength in the security, and has low encryption/decryption time with high throughput compared to HuXia algorithm.