ISSN 2348-1196 (print) International Journal of Computer Science and Information Technology Research ISSN 2348-120X (online) Vol. 8, Issue 4, pp: (66-71), Month: October - December 2020, Available at: www.researchpublish.com
Visual Crystal for Access Structure by Multipixel Encoding with Variable Block Size Alaudeen.B.M*., Dr.G.Tholkappia Arasu.** *Research Scholar, ** Professor *Manonmaniam Sundaranar University, Tirunelveli.,**A.V.S.College of Technology , Salem
Abstract: Multi-pixel encoding is an emerging method in visual Krystal for that it can encode more than one pixel for each run. However, in fact its encoding efficiency is still low. This paper presents a novel multi- pixel encoding which can encode variable number of pixels for each run. The length of encoding at one run is equal to the number of the consecutive same pixels met during scanning the secret image. The proposed scheme can work well for general access structure and chromatic images without pixel expansion. The experimental results also show that it can achieve high efficiency for encoding and good quality for overlapped images. Keywords: Visual secret sharing, cheating immune, anonymity.
1. INTRODUCTION [1]
In 1994, Naor and Shamir first presented a novel secret sharing scheme called visual cryptography which differs extremely from the traditional cryptography. It divides a black-white image into n shares. Among those shares, any k or more ones are stacked and then a discernable image appears; otherwise any less than k ones together can reveal nothing about the original secret. The advantages of this visual secret sharing (VSS) scheme are very clear in that those complex computations needed in traditional cryptography are redundant and the decryption even doesn’t need any knowledge of cryptography or any help with computer; it only depends on the mankind’s visual system. Actually, the Naor-Shamir scheme implements a (t, n) threshold access structure. Generally speaking, an access structure is a rule, which defines how to share a secret. The most familiar examples are (n, n) and (t, n) threshold access structures. A (t, n) threshold structure rules that any t or more out of n participants can cooperate to reveal the secret image and any less than t participants get nothing about the secret image. However, threshold structure is only one special case of the so-called general access structure. Usually, a general access structure is denoted as Γ = {A0 ,A1} , where A0 and A1 are sets of subsets of all participants and A0 ∩A1 = ∅ Furthermore,A0 denotes a collection of forbidden sets and A1 denotes a collection of qualified sets. It is easily known that stacking all the shares held by the participants of a qualified set can recover the secret image; but stacking all the shares held by the participants of a forbidden set cannot reveal any information about the secret image. For example, in a system with four participants, we can let A1 = {{1, 2}, {2, 3}, {3, 4},{1, 2, 3}, {1, 2, 4}, {1, 3, 4},{2, 3, 4}, {1, 2, 3, 4}}, which implies that A0 = {{1}, {2},{3}, {4}, {1, 3}, {1, 4}, {2, 4}}. Therefore, we can learn that stacking share 1 and share 2 can recover the secret image; however, stacking share 1 and share 4 can reveal nothing about the secret image.
2. PREVIOUS WORKS After the Naor-Shamir scheme appears, many related researches and some extended VSS schemes come forth. Some of which can be used for gray-scale or chromatic images [2, 3], general access structure [3, 4], ideal contrast [5],cheating immune [6, 7], anonymity [8] and multiple images hiding.
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