本論文提出一個兩層式結構的(t, s, k, n)關鍵秘密影像分享門檻技術，當中有s個關鍵分享影像和n-s個非關鍵分享影像，且還原回秘密影像時，需收集t個關鍵分享影像和k個分享影像，其中分享影像包括關鍵分享影像和非關鍵分享影像。在此技術中定義一個參數m，m=1時，將獲得最小的總分享影像的影像大小及關鍵分享影像的影像大小接近於非關鍵分享影像的影像大小；m=t時，將獲得關鍵分享影像的影像大小和非關鍵分享影像的影像大小為2倍關係，並且能凸顯關鍵分享影像的重要性，此外，本論文克服前人Chen的方法[3]所存在之不滿足分享門檻問題，不會造成還原時以滿足單一門檻能獲得部份秘密影像資訊的缺點，實驗結果顯示，本文方法可歸納出兩種最佳分享率的分享結果。

This paper presents a two-layered structure for optimally sharing a secret image among s essential and n-s non-essential shared shadows using the (t,s,k,n) essential thresholds, that t essential shared shadows and totally k shared shadows are needed to recover the secret image. The presented two-layered structure includes one user-defined parameter m to determine different kinds of optimal results. m=1 leads to minimum size of total shared shadows (ST) and size of an essential shared shadow is close to size of a non-essential shared shadow. On the other hand, m=t leads to size of an essential shared shadow being twice of size of a non-essential shared shadow to signify the importance of an essential shared shadow. Moreover, the proposed structure overcomes the threshold fulfillment problem in Chen’s scheme [13]. Theoretical analyses and experimental results show that the proposed scheme exhibits secure with optimal sharing ratios among related works.

目錄
目錄	IV
圖目錄	VI
表目錄	VII
第一章 緒論	1
1.1 研究背景與動機	1
1.2 論文架構	4
第二章 相關研究	5
2.1 Li等人的方法	5
2.2 Yang等人的方法	6
2.3 Chen的方法	7
2.4 各篇方法之討論	7
第三章 本論文方法	9
3.1 GF(28)在秘密分享中的運算	9
3.2 兩層式(t, s, k, n) ESIS之演算法	10
3.3 分享率的分析與比較	14
第四章 實驗結果及討論	19
4.1 實驗結果	19
4.2 比較與討論	26
第五章 結論	29
參考文獻	30
英文論文	33
 
圖目錄
圖2.1 Chen (3, 5, 5, 8)關鍵秘密影像分享中，不滿足分享門檻的2個例子	8
圖3.1本論文兩層式關鍵秘密影像分享(ESIS)的分享流程圖	12
圖4.1本論文方法在(3, 5, 5, 8)關鍵秘密影像分享門檻中，且參數為m=t=3之分享實驗圖	21
圖4.2本論文方法在(3, 5, 5, 8)關鍵秘密影像分享門檻中，且參數為m=1之分享實驗圖	22
圖4.3本論文方法在(3, 5, 5, 8)關鍵秘密影像分享門檻中，且參數為m=t=3之還原實驗圖	24
圖4.4本論文方法在(3, 5, 5, 8)關鍵秘密影像分享門檻中，且參數為m=t=3之遭到攻擊後的還原實驗圖	25

 
表目錄
表3.1本論文方法和三個(t, s, k, n)關鍵秘密影像分享方法中的分享率比較表	18
表4.1本論文方法和三個(3, 5, 5, 8)關鍵秘密影像分享中的分享率比較表	27
表4.2本論文方法和三個(2, 3, 5, 7)關鍵秘密影像分享中的分享率比較表	28

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