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Abstract Optical encryption techniques have played a vital role in the field of optical information processing during the last decade. Special and reliable security in the transmission and storage of images is needed in several applications like pay TV, medical or biometric images for storage or transmission, confidential video conferencing over optical fiber, military applications, police identification procedures, online banking systems, governmental services, identity cards, etc. This thesis is ultimately and entirely concerned with the optical image encryption. It summarizes a group of efficient metrics that can be used for performance evaluation of these cryptosystems. Besides, two approaches for optical image encryption are suggested. The first approach is based on chaotic Baker map and double random phase encoding. It provides a good results for noise immunity. The second approach is based on the Arnold cat map and double random phase encoding. Simulation experiments have shown that the proposed cryptosystems are robust to several cryptanalysis attacks with high immunity to noise and a moderate execution time. Comparison between two approaches gives better results analysis in second approach than first approach for an encryption quality. Finally, the thesis elaborates a general framework for a multi-level security system implementing in optical communications networks systems. The performance of this system has been thoroughly studied with optical image encryption enhancement, and the simulations have brought out promising results. Optical encryption techniques have played a vital role in the field of optical information processing during the last decade. Special and reliable security in the transmission and storage of images is needed in several applications like pay TV, medical or biometric images for storage or transmission, confidential video conferencing over optical fiber, military applications, police identification procedures, online banking systems, governmental services, identity cards, etc. This thesis is ultimately and entirely concerned with the optical image encryption. It summarizes a group of efficient metrics that can be used for performance evaluation of these cryptosystems. Besides, two approaches for optical image encryption are suggested. The first approach is based on chaotic Baker map and double random phase encoding. It provides a good results for noise immunity. The second approach is based on the Arnold cat map and double random phase encoding. Simulation experiments have shown that the proposed cryptosystems are robust to several cryptanalysis attacks with high immunity to noise and a moderate execution time. Comparison between two approaches gives better results analysis in second approach than first approach for an encryption quality. Finally, the thesis elaborates a general framework for a multi-level security system implementing in optical communications networks systems. The performance of this system has been thoroughly studied with optical image encryption enhancement, and the simulations have brought out promising results. Optical encryption techniques have played a vital role in the field of optical information processing during the last decade. Special and reliable security in the transmission and storage of images is needed in several applications like pay TV, medical or biometric images for storage or transmission, confidential video conferencing over optical fiber, military applications, police identification procedures, online banking systems, governmental services, identity cards, etc. This thesis is ultimately and entirely concerned with the optical image encryption. It summarizes a group of efficient metrics that can be used for performance evaluation of these cryptosystems. Besides, two approaches for optical image encryption are suggested. The first approach is based on chaotic Baker map and double random phase encoding. It provides a good results for noise immunity. The second approach is based on the Arnold cat map and double random phase encoding. Simulation experiments have shown that the proposed cryptosystems are robust to several cryptanalysis attacks with high immunity to noise and a moderate execution time. Comparison between two approaches gives better results analysis in second approach than first approach for an encryption quality. Finally, the thesis elaborates a general framework for a multi-level security system implementing in optical communications networks systems. The performance of this system hasbeen thoroughly studied with optical image encryption enhancement, |