Sethulakshmi Unnikrishnan Department of Computer Science andTechnology Adi Shankara Institute of Engineering and Technology, KaladyKerala,India Email:[email protected] I.
Abstract: Inthe art of visual cryptography, many shares are generated which are illogicalcontaining certain message within themselves. When all shares are piledjointly, they tend to expose the secret of the image. The notion of visualsecret sharing scheme is to encrypt a secret image into n illogical shareimages. It is unable to reveal any data on the original image if at least oneof the shares is not achieved.
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The original image, in fact, is realized byoverlapping the entire shares directly, in order that the human visual systemis competent to identify the collective secret image without employing anycomplicated computational tools. Therefore, they are communicated steadily asnumber of shares. The elliptic curve cryptography approach, in turn, is employedto augment the privacy and safety of the image. The new-fangled technique isutilized to generate the multiple shares which are subjected to encryption anddecryption. II.Earlier methods used: A. Black And White Visual Cryptography Schemes Naor and Shamir’s proposed anencryption scheme to convert a binary image into two shares.
In this schemeeach share pixel p is encoded into two white and two black pixels each sharealone gives no clue about the pixel p whether it is white or black. Secret Ms.Divya DDepartment of Computer Science andTechnologyAdi Shankara Institute ofEngineering and Technology, Kalady Kerala,IndiaEmail:divya.
[email protected] image is visible only when bothshares are stacked on each other. Visual secret sharing schemes based on theThreshold value of mixed XOR and OR operation with reversing and based onbinary linear error- correcting code 2 The main disadvantage of thisschemes is that it can only be used for one set of confidential messages can beembedded, therefore for large amounts of confidential messages several shareshave to be generated. B. Color Visual Cryptography Schemes Until the year 1997 visualcryptography schemes were applied to only black and white images. First coloredvisual cryptography scheme was developed by Verheul and Van Tilborg . A coloredsecret images can be shared with the concept of arcs to construct a coloredVCS. In colored VCS one pixel is converted into m subpixels, and each subpixelis further divided into c color regions.
In each subpixel, there is exactly onecolor region is colored, and other color regions are black. The color of onepixel depends on the interrelations between the stacked subpixels. 3 This scheme offers a perfectreconstruction while producing shares with size smaller than the size of inputimage using maximum separable distance. This scheme provides pixel expansionless than one.