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New Visual Secret Sharing Schemes With Non-Expansible Shadow Size Using Non-binary Sub Pixel

New Visual Secret Sharing Schemes With Non-Expansible Shadow Size Using Non-binary Sub Pixel. Ching-Nung Yang Yun-Hsiang Liang Wan-Hsiang Chou National Computer Symposium on Information security. Outline. 介紹 NEVSS (Non-Expansible VSS) 介紹 Visual Cryptography 上的 Contrast 和 Security 結論.

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New Visual Secret Sharing Schemes With Non-Expansible Shadow Size Using Non-binary Sub Pixel

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  1. New Visual Secret Sharing Schemes With Non-Expansible Shadow Size Using Non-binary Sub Pixel Ching-Nung Yang Yun-Hsiang Liang Wan-Hsiang Chou National Computer Symposium on Information security

  2. Outline • 介紹 NEVSS (Non-Expansible VSS) • 介紹 Visual Cryptography上的Contrast 和 Security • 結論

  3. NEVSS vs. Conventional VSS • 不同點: 1. Addition “ADD” vs. Boolean “OR” 2. Non-Binary{W,G,B} vs. Binary{W,B} 3. Non-Expansible vs. Expansible

  4. Non-Expansible Method -- A (2,2) NEVSS Scheme Example: Original Image Shadow Image I Shadow Image II

  5. Non-Expansible Method -- A (2,2) NEVSS Scheme Example: Pixel Value: --0: white --1: gray --2: approximate black --C0 is used to represent “white”. --C1 is used to represent “black”. 可知: Shadow image: {white,gray} target image: {white,gray,black}

  6. NEVSS--Contrast Definition -- a (2,2) NEVSS Scheme Example: When stacking two shadows. The dominant color is “0” (white), because “0” is the biggest contrast among the colors “0”,”1”,”2” in λandγ. Pλand Pγare the probabilities of the dominant color in the set λandγrespectively. Now , Pλ=1/2, Pγ=0, the difference Pλ-Pγ=1/2, the holds the first and the second condition.

  7. NEVSS--Security Definition We randomly chooses one column matrix in C0 and C1. So for each shadow every pixel will be “0” (white) or “1” (gray) half and half, and one cannot see any thing from the shadow.

  8. NEVSS The major difference between two schemes is that our scheme uses non-binary operation and the conventional scheme uses Boolean operation.

  9. 他的結論 • In this paper, we have presented new (2,2),(2,n), and (k,k) NEVSS schemes . However, the general method for constructing (k,n) NEVSS schemes may need the further studies. • 在2001年, 提出動態式的NEVSS

  10. 曾 經 水 滄 為 海 難

  11. 我的結論 • 此篇論文 : Contrast and Security不能兼顧 • M. Naor and A. Shamir : 可同時兼顧 Contrast and Security • 我認為我的論文也可同時兼顧Contrast and Security

  12. 我的論文 • Contrast : 已歸納在各個scheme中可擁有的最大contrast,也就是論文中的T值 • Security : 由於Shadow Image(小學生) 和 Recovered Image(高中生)是處在2個不同的Grayleve上,所以分享者最多只能知道Recovered Image’s graylevel (國中生,高中生,大學生……)必大於Shadow Image.

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