15-08-2011, 01:59 PM
Pls send the seminar report on VISUAL CRYPTOGRAPHY
[b]ABSTRACT:[/b]
Visual cryptography is a popular solution for image encryption. Using secret sharing concepts, the encryption procedure encrypts a secret image into the so-called shares which are noise-like secure images which can be transmitted or distributed over an untrusted communication channel. Using the properties of the human visual system to force the recognition of a secret message from overlapping shares, the secret image is decrypted without additional computations and any knowledge of cryptography.
Visual cryptographic solutions operate on binary or binarized inputs. Therefore, natural (continuous-tone) images must be first converted into halftone images by using the density of the net dots to simulate the original gray or color levels in the target binary representation. Then, the halftone version of the input image is used instead of the original secret image to produce the shares. The decrypted image is obtained by stacking the shares together. Because binary data can be displayed either as frosted or transparent when printed on transparencies or viewed on the screen, overlapping shares that contain seemingly random information can reveal the secret image without additional computations or any knowledge of cryptographic keys. However, due to the nature of the algorithm, the decrypted image is darker, contains a number of visual impairments, and most of visual cryptography solutions increase the spatial resolution of the secret image. In addition, the requirement for inputs of the binary or dithered nature only limits the applicability of visual cryptography.
Reference: http://studentbank.in/report-visual-cryp...z1V5HeMN3c
