الفهرس 
Network securityOnly 14 pages are availabe for public view
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Abstract
The revolution in information and communication technology has become linked to the development of societies in our time, as it is considered the most important means of transferring developing societies to more developed societies. So, The Egyptian government wants to create a digital Egypt and society that uses technology in all aspects of life. As a result, it aims to improve government agencies’ digital services as well as the development of information, and communication technology infrastructure. All of this need strong information security to provide privacy and confidentiality of the information in circulation.
Information security is the science that provides data protection from all threats, risks, and security breaches through tools and measures taken for this matter. Encryption holds a special place in information security sciences, it is the backbone to ensure the confidentiality of information because it protects the data from attackers and unauthorized persons. Encryption systems are classified as asymmetric or symmetric based on their key distribution. In asymmetric encryption, the encryption depends on private and public keys. On the other hand, symmetric encryption depends on only symmetric keys for encrypting and decrypting the data.
Researchers have become more interested in generating both private keys, public keys, and symmetric keys. There is a lot of research for the generation of encryption keys.
This thesis provides a study in the realm of symmetric encryption that uses chaotic systems to produce strong and secure subkeys. Generation subkeys for Advanced encryption standard (AES) and Blowfish encryption algorithm.
AES and Blowfish are strong symmetric block cipher encryption algorithms. Both Encryption algorithms use symmetric key for encryption and
Decryption. Using strong symmetric key for encryption algorithm adds strong resistance against different attacks, so it’s important issue to design strong symmetric key.
Chaotic systems describe very complicated dynamical system that difficult to predict and control. chaotic systems have some properties like deterministic that means the chaotic systems have a mathematical model that describe the system behavioral. Also chaotic systems are very sensitive to initial conditions (butterfly effect) and any change in initial condition leads to a significant change in the system behavioral and the output [1].
Making a modification to blowfish encryption algorithm is proposed by replacing the standard round function by light weight function to reduce the resources utilization area and increase the speed. where the standard blowfish consumes large resources from the FPGA platform.
Numerical analysis is applied to the proposed technique, we utilized MATLAB to test our proposed technique through simulation, numerical operations. Statistical Tests (Entropy, Mean Square Error, Correlation Coefficient and NIST test) have been done on the output of the proposed encryption algorithms
Hardware digital realization of all introduced systems is implemented using the Xilinx Virtex_5 Field Programmable Gate Arrays (FPGA) kits. Also, the proposed technique is designed using VHDL and Xilinx ISE 14.7 tool is used in both VHDL simulation and hardware implementation stages.
Key words (CHAOTIC SYSTEMS, LORENZ SYSTEM, FPGA, AES, BLOWFISH).