الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Data is the essence of any communication system. When data is being transmitted over insecure network, it could be revealed by an adversary and the whole communications might be compromised. Information security tools such as cryptography and steganography could be used to secure the transferring or storing of such data. Cryptography is the science of using mathematical functions to transform data from its clear readable form to another scrambled unreadable form for the unauthorized parties. Steganography, on the other hand, hides the existence of such data while transmission by hiding it in another innocent cover message. If this data is highly classified, the more level of security is then required. By combining such tools together, a higher security level would be achieved, and more security layers could be added to secure that data.
In this thesis, a hybrid model was introduced based on the combination of cryptography with steganography. Blowfish symmetric cipher, visual cryptography and least significant bit steganographic algorithm were blended to form the proposed model. First, the secret message was encrypted using blowfish symmetric algorithm where fingerprint of the sender is required in the key expansion process of the blowfish algorithm before encrypting the data takes place. The resulting ciphertext is then applied to a (2, 2) visual cryptographic scheme producing two noisy shares each has no clue about the ciphertext. Finally, these shares are embedded into two innocent cover images for later transmission.
Many evaluation criteria were used to evaluate the proposed model. The quality of the Stego images was evaluated using PSNR, MSE, and Image Histogram. The results out from the proposed model had acceptable PSNR.