Design and implementation of visual cryptography system.

number: 
730
إنجليزية
department: 
Degree: 
Imprint: 
Computer Science
Author: 
Mazin Kasim Zghier Al-Rawi
Supervisor: 
Dr.Adeeb H. Sulaiman
Dr.Venus W. Samawi
year: 
2002
Abstract:

The ability to encrypt written materials such as: printed text, handwriting notes, and pictures in a secure way, and decode the material with human visual system is the idea behind our research. This form of data encryption is called Visual Cryptography (VC) which could be considered relatively new in the area of image cryptography. The basic idea of VC is splitting an image into two or more separate images called shares. These shares contain no information concerning the original image. To decode the encrypted image, that is, to reveal the original image back, the shares should be stacked together (taking in consideration they must be correctly aliened on each other). Visual cryptography allows a secret image to be encoded and distributed among set of participants (N-participant) such that certain qualified sets of participants (K-participant) may reconstruct the image without any computation. In computer, decoding is done by Oring or Xoring the corresponding subpixels in all qualified shares. In this work, two threshold VC schemes ("K out of K" and "K out of N") are implemented. In K out of K VCS all K-participants shares must stacked together to reveal the original image (if K-l shares stacked, the original image can't be reconstructed). While in K out of N VCS, the original image can be reconstructed from K shares that belong to qualified set of participants. Two types of images were taken in consideration at which a VC system is constructed for black and white images (using both schemes) and a proposed VC system is constructed for palette images (256-cdlor and gray scaled) using K out of K scheme only.