In this paper a Genetic Algorithm (GA) is proposed to attack an Arabic encrypted text by Vigenere cipher. The frequency of occurrence of Arabic letters has been calculated by using the text of the holy book of Quran, since it has rich language features compared to many other books. The algorithm is tested to find the key letters for different ciphertext sizes and key lengths. The results shows 100% correct letters retrieved from medium size ciphertext and short key length, while 90% of the ciphertext is retrieved from long ciphertext and medium key length, and 82% of the ciphertext is retrieved from long ciphertext and long key.
Recently, chaos theory has been widely used in multimedia and digital communications due to its unique properties that can enhance security, data compression, and signal processing. It plays a significant role in securing digital images and protecting sensitive visual information from unauthorized access, tampering, and interception. In this regard, chaotic signals are used in image encryption to empower the security; that’s because chaotic systems are characterized by their sensitivity to initial conditions, and their unpredictable and seemingly random behavior. In particular, hyper-chaotic systems involve multiple chaotic systems interacting with each other. These systems can introduce more randomness and complexity, leading to stronger encryption techniques. In this paper, Hyper-chaotic Lorenz system is considered to design robust image encryption/ decryption system based on master-slave synchronization. Firstly, the rich dynamic characteristics of this system is studied using analytical and numerical nonlinear analysis tools. Next, the image secure system has been implemented through Field-Programmable Gate Arrays (FPGAs) Zedboard Zynq xc7z020-1clg484 to verify the image encryption/decryption directly on programmable hardware Kit. Numerical simulations, hardware implementation, and cryptanalysis tools are conducted to validate the effectiveness and robustness of the proposed system.