Encryption and Decryption Process of a Secret Natural Colour Image Based on K out of N VSS Scheme
Debabrata Bhattacharya1, Harinandan Tunga2

1Debabrata Bhattacharya, Department of Applied Electronics & Instrumentation Engineering, Regional Computer Centre Institute of Information Technology, Kolkata (West Bengal), India.
2Harinandan Tunga, Department of Computer Science and Engineering, Regional Computer Centre Institute of Information Technology, Kolkata (West Bengal), India.

Manuscript received on 15 February 2016 | Revised Manuscript received on 25 February 2016 | Manuscript Published on 28 February 2016 | PP: 90-97 | Volume-5 Issue-3, February 2016 | Retrieval Number: C4409025316/16©BEIESP
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© The Authors. Blue Eyes Intelligence Engineering and Sciences Publication (BEIESP). This is an open access article under the CC-BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Abstract: The Visual Secret Sharing (VSS) scheme is a cryptographic tool used to encode a secret image into several shares, each of which separately does not reveal any information of the secret image. Visual Cryptography (VC) schemes hide the secret image into two or more images which are called ‘shares’. The secret image can be recovered simply by stacking the shares together without any complex computation involved. The shares are very safe because separately they reveal nothing about the secret image. In this paper, a generalized version of Visual Cryptography is mentioned. Here an image (secret image) can be hidden in ‘n’ numbers of cover images. This generalized version helps the user to attain the desired level of encryption. Also after successful transmission the secret image can be re-discovered using a simple decryption algorithm. The aim of our paper is that a sender sends ‘n’ number of colored images with a hidden secret image in it by encryption and the receiver recovers the secret image from it by decryption. The proposed approach uses meaningful shares (cover images) to hide the colored secret image and the recovery process is lossless. In this paper, we propose a proportionate algorithm which successfully encrypts a secret image into any number of cover images as chosen by the user. Here the amount of original image share depends upon the pixel values of the cover images. Also a critical value on the number of images is determined which helps in optimizing our aim with the complexity.
Keywords: Visual Cryptography (VC), Secret Image, Hidden Secret Image, Proportionate Algorithm, Human Vision System (HVS)

Scope of the Article: Cryptography and Applied Mathematics