What is Visual Cryptography Visual Cryptography is a special encryption technique to hide information in images in such a way that it can be decrypted by the human vision if the correct key image is used. The technique was proposed by Naor and Shamir in 1994. Visual Cryptography uses two transparent images. One image contains random pixels and the other image contains the secret information. It is impossible to retrieve the secret information from one of the images. When the random image contains truely random pixels it can be seen as a one-time pad system and will offer unbreakable encryption. How Visual Cryptography works Each pixel of the images is divided into smaller blocks. In the table on the right we can see that a pixel, divided into four parts, can have six different states.If a pixel on layer 1 has a given state, the pixel on layer 2 may have one of two states: identical or inverted to the pixel of layer 1. We can now create the two layers. Additional information
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