14-02-2015, 07:43 PM
i want pdf AN EXTENDED VISUAL CRYPTOGRAPHY SCHEME WITHOUT PIXEL EXPANSION FOR HALFTONE IMAGES
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visual cryptography pdf
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i want pdf AN EXTENDED VISUAL CRYPTOGRAPHY SCHEME WITHOUT PIXEL EXPANSION FOR HALFTONE IMAGES
17-03-2017, 12:43 PM
Visual cryptography is a cryptographic technique that allows visual information (images, text, etc.) to be encrypted in such a way that the decryption becomes the work of the person to be deciphered through visual reading. One of the best known techniques has been credited to Moni Naor and Adi Shamir, who developed it in 1994. They demonstrated a secret visual exchange scheme, where an image was divided into n actions so that only someone with all n actions could Decrypt The image, while any n - 1 actions did not reveal information about the original image. Each action was printed on a separate transparency, and the decryption was performed by superimposing the actions. When all n actions were overlapped, the original image would appear. There are several generalizations of the basic schema that includes k-out-of-n visual cryptography.
Using a similar idea, transparencies can be used to implement one-time encryption, where one transparency is a shared random pad, and another transparency acts as the ciphertext. Typically, there is an expansion of the space required in visual cryptography. But if one of the two parts is recursively structured, the efficiency of visual cryptography can be increased up to 100%.
Some background of visual cryptography is in patents of the sixties. Other background is the work on perception and secure communication. Visual cryptography can be used to protect biometric templates in which decryption does not require any complex computation.
Visual Cryptography is a special encryption technique to hide the information in the images in such a way that it can be deciphered by 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 contains the secret information. It is impossible to retrieve the secret information of one of the images. Both transparent images or layers are necessary to reveal the information. The easiest way to implement visual cryptography is to print the two layers on a transparent sheet.
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