الملخص

In order to achieve communication security, cryptography and information hiding in different media are used. In this work, a system for hiding text in Internet files namely, HTML and XML has been built. Two proposed algorithms have been designed and implemented to embed and extract secret information from these files. Hiding in HTML files was done by first encrypting the message using Linear Feedback Shift Register (LFSR) and embed the encryption key into the HTML tags. Then, the encrypted secret message was embedded into an image in the HTML page. Hiding in XML files was achieved using non linear feed back shift register to encrypt the secret message. The resultant encryption key was embedded inside XML definition file namely, Document Type Definition (DTD) file which is invisible to the user. The encrypted message was embedded inside the XML component of the file.             Experimental results demonstrated that the proposed algorithms are secure and efficient. The image carrying the secret information is identical (by Human Visual System HVS) to the original image as well as the ability to embed a lot of information inside the files. Visual C++ was used to access Internet files whereas Matlab Version 7 was used to implement the used encryption methods and graphical user interface.