臺灣博碩士論文加值系統

視覺式秘密分享的概念是由Noar及Shamir在1994年提出。這是一種可將所要傳送的秘密圖片，分解成多張無意義的子圖片，使得滿足足夠的子圖片便能還原原有秘密圖片的一種技術。此技術的特點在於解碼過程中只需利用人眼將圖片重疊而不需藉助任何運算工具，具有『密碼，看得見』的特殊意義及效果，十分方便，而且安全性高、製作簡單，有著極高的應用價值。
基於此，本論文最主要的目的是將此技術應用至日常生活上。製作出秘密分享技術之應用軟體。在軟體中，我們不但將密碼技術應用在有關於娛樂休閒的魔術卡片及摸彩彩卷、並應用於資訊教育之數字遊戲，另外還應用在日常生活的電子郵件以及企業上的保密傳真共五個項目。此軟體不但適合讓一般民眾用來做保密郵件的傳遞及卡片、彩券等娛樂上的製作使用，亦適合業界人士之間互相傳遞機密文件，及學齡兒童的算數教育上。我們希望能藉由此軟體傳達保密安全之重要性，讓大眾瞭解密碼與日常生活之相關性，並懂得使用密碼技術保障個人隱私，達到寓教於樂之效果。
在學理上，我們提出了一個新的秘密分享技術，稱之為Top-down秘密分享技術，此技術最大的特點為能同時隱藏兩個訊息（P1與P2）在兩張shadows（T1與T2）中，當T1與T2相疊合時，可還原P1；將T1反轉，再與T2疊合時，可把P2還原。而在實際應用情形方面，我們討論了關於傳真功能使用時會遭遇的失真問題，並對於此問題提出我們的解決方案。

Visual secret sharing (VSS) scheme was proposed by Noar and Shamir in 1994. This is a technique that divided the secret image that will be transformed into several meaningless shadows and certain qualified subsets of shadows enable to recover the secret image by "eyes". The main characteristic of the VSS scheme is in its decoding process that the original secret can be perceived directly by the human visual system without the knowledge of cryptography and the cryptographic computations. It possesses a special meaning and effect that "the secret codes are visible".
In this thesis, our main objective is to use the VSS scheme in our daily life and to implement an application system. The whole system is divided into five parts: magic card, lottery, arithmetic quiz, electronic mail, and fax. Our system is suitable for entertainment, information education, and secret message sending. And we also combine VSS scheme with E-mail and fax to be used on commerce. We implement the VSS scheme into software, so as to convey the importance of privacy safeguarded.
In theory, we propose a new VSS scheme, top-down VSS scheme. The characteristic of the scheme is that it can conceal two secret messages (P1 and P2) on two shadows (T1 and T2) at the same time. When T1 and T2 stacked together, P 1 is recovered. By reversing T1 and covering it on T2, P 2 is revealed. In real application of VSS scheme, we discuss the distortion about using fax function. And we propose our solution for this question.

Chapter 1 Introduction ………………………………………………… 1
1.1 Visual Secret Sharing ……………………………………………… 1
1.2 Research Motives …………………………………………………… 2
1.3 Overview …………………………………………………………… 3
Chapter 2 Visual Secret Sharing ………………………………………… 5
2.1 The Basic Model …………………………………………………… 6
2.1.2 (2, 2) Scheme …………………………………………………… 8
2.1.3 (3, 3) Scheme …………………………………………………… 9
2.1.4 (4, 4) Scheme …………………………………………………… 10
2.2 Types of VSS Scheme used in the System ………………………… 11
2.2.1 (2, n) Scheme …………………………………………………… 11
2.2.2 (1Rn) Scheme …………………………………………………… 12
2.2.3 (1, 2, n) Scheme ………………………………………………… 14
2.3 The Top-down VSS Scheme ……………………………………… 16
2.3.1 Codebook …………………………………………………………16
2.3.2 Security Analysis ………………………………………………… 21
2.3.3 Implemented Example …………………………………………… 25
Chapter 3 Application System ………………………………………… 27
3.1 Magic Card ………………………………………………………… 27
3.2 Lottery …………………………………………………………… 28
3.3 Arithmetic Quiz …………………………………………………… 29
3.4 Electronic Mail …………………………………………………… 30
3.5 Fax ……………………………………………………………… 31
Chapter 4 Implementation …………………………………………… …33
4.1 Hardware and Development Tools ………………………………… 34
4.2Application Interface……………………………………………… 35
4.3 Other Functions …………………………………………………… 40
Chapter 5 On the Resolution in VSS Schemes …………………………… 45
5.1 The Problems of Application in VSS Scheme ………………………… 45
5.2 The Contrast Discussed in VSS scheme ……………………………… 45
5.3 The Solution of the Problem ………………………………………… 46
Chapter 6 Conclusion …………………………………………………… 51
6.1 Our Contribution …………………………………………………… 51
6.2 Future Work ………………………………………………………… 51
Bibliography …………………………………………………………… 53

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