الفهرس 
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Abstract
Radio frequency identification (RFID) system is a contact-less automatic identification
system. RFID was developed very early and has been recently widely used in many areas recently. It has received much attention in many industries like manufacturing companies,material flow systems, warehouse management, location tracking, and mobile remote sensing,etc. A RFID system consists of three main components, radio frequency (RF) tags or transponders, a reader or transceiver, and a RFID middleware.The increasing use of these systems has led to a higher risk of theft of data. Security methods need to be improved via encryption to counter the latest techniques of data robbery. The
RFID technology is secured using different ways of data encryption. A Substitution Box (S-Box) is the core of the block ciphers encryption and the basis of modern symmetric cryptosystems. A good design of the S-Box can increase the security of the encryption algorithm.In this thesis, two existing S-Boxes for Advanced Encryption Standard (AES), namely Static S-Box and Dynamic S-Box, are studied. Three new algorithms are proposed to generate modified S-Boxes; the first is the key-and-plaintext dependent S-Box using an RC4 algorithm, and the second is the key-and-plaintext dependent S-Box using a RC4 Henon chaotic map (HCM) algorithm, and the third is a key and plaintext-dependent S-Box using an improved RC4 encryption algorithm with Logistic Chaotic Maps (LCM).The thesis aims to demonstrate the efficiency of the proposed S-Boxes compared to the existing ones. All five S-Boxes give good results, but because the proposed S-Boxes depend on affine transformation, complexity and periodicity are ensured. In addition, the key-andplaintext dependent S-Box using the RC4 HCM algorithm where the Henon map is implemented, increases security and makes the differential and linear cryptanalyses more difficult.The comparison between the state of the art S-Boxes and the proposed S-Boxes demonstrates that the use of the LCM increases the security of the S-Box and makes the differential and linear cryptography more interesting for researchers. In particular, using the strict Avalanche test, we demonstrate that the proposed S-Box improves the security by achieving a cipher text bit-flip ratio of 0.4765, which is closer to 0.5 (where half the bits are flipped), while maintaining a minimum elapsed time of 19 ms for encryption and decryption.