Abstract
Steganography and Cryptography are two popular ways of sending information in a secret way. One hides the existence of the message and the other distorts the message itself. Cryptography used with steganography to make its security more robust. Furthermore, we propose a system that combined cryptography and steganography to provide an effective way to protect the secret text messages from unauthorized users. In this thesis, we proposed using of the fuzzy logic (FL) algorithm to encrypt the secret text message. Also, we proposed using the least significant bit (LSB) technique to hide the encrypted secret text message in the least significant bits of the gray image. The efficiency and accuracy of the FL algorithm based on some measurements. Two of these measures used to measure the image quality: Mean-Squared Error (MSE) and Peak Signal-to-Noise Ratio (PSNR), also, we measured the required time to execute this algorithm (execution time). The results obtained from the FL algorithm werecompared with the classical encryption algorithm (AES). The results were satisfactory, the metrics scoring of FL algorithm that applied to one of the used image rated 0.097, while the metrics scoring of AES algorithm rated 0.13. According to these results, the FL algorithm gave the best image quality (stego-image). Therefore, FL algorithm was better in performance than the other algorithm. In addition, stego-image has been tested against some attacks such as noise (salt and pepper). The results based on the ratio of similarity between the original secret text message and the extracted secret text message from the stego-image, where the range of the similarity ratio for the FL algorithm that applied to the used images between 62.5% and 100%, while the range of the similarity ratio for the AES algorithm between 0% and 100%. Those results demonstrated strength of the image (stego-image) of the FL algorithm against some attacks.