Visual Encryption Using Multilevel Scrambling Followed by Affine Encryption Technique
Keywords:Cryptography, Matrix algorithms, Scrambling, Horizontal Correlation, Vertical Correlation
In the present paper, we report an effective method of multilevel scrambling followed by affine encryption, which may be used as one of the useful tools in visual cryptography. A sample image is scrambled for six times using a specific algorithm. Toner distributions of scrambled images were studied using their histograms. The results of histogram expressed that the effectiveness of scrambling increased with its increasing stages and it becomes almost ideal when the image after affine encryption is taken. In order to judge the complexity level of scrambling, horizontal & vertical correlation of adjacent pixels and Information Entropy of different scrambled images were also calculated. Values of horizontal & vertical correlation and information entropy reflected that the complexity and randomness of pixels increase with increasing stages of scrambling. It also indicated that the randomness doesn’t change much after the fifth stage of scrambling and affine encryption enhanced the level of security by a large extent.
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