Keywords : LFSR


Voice Security Using Hybrid Algorithm

Alyaa Moufaq Abdul Majeed Haleem

AL-Rafidain Journal of Computer Sciences and Mathematics, 2010, Volume 7, Issue 2, Pages 107-118
DOI: 10.33899/csmj.2010.163889

This research deals with constructing and implementing a new digital voice security Algorithm based on hiding large amount of data (sound file) in a 24 bits host color image (RGB image). The proposed method starts with speech compression to convert human speech into an efficiently encoded representation that can later be decoded to produce a close approximation of the original signal. The process of compression is achieved by first computing Discrete Wavelet Transform (DWT), truncating small-valued coefficients and then efficiently encoding them. The stream bits output from coder are encrypted using Linear Feedback Shift Register (LFSR) algorithm. These enciphered bits are then embedded into the image blocks. A binary key matrix and weight matrix are used as a secret key to protect the hidden information. The algorithm can hide as many as  bits of data in the image by changing one bit in each block of size . High security algorithm was achieved using three layers to make it difficult to break by attacker. The algorithm has been implemented using MATLAB.
 

Encryption & Hiding Information in Internet Files HTML & XML

Dujan B. Taha; Ahmed S. Nori; Najla B. Ibraheem

AL-Rafidain Journal of Computer Sciences and Mathematics, 2010, Volume 7, Issue 1, Pages 67-93
DOI: 10.33899/csmj.2010.163864

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.