資訊隱藏屬於秘密通訊的一種類型，安全、不可察覺性、及高藏密容量為其主要之訴求。近年來，許多的資訊隱藏技術被提出來，但大部分的研究是以數位影像為主，而在數位音訊資訊隱藏部分，卻只有較少數的技術被提出來，究其原因，主要是由於音訊為一維訊號，人類在接收時比影像來的更敏銳，因此，在不可感知的訴求下，較難達成高容量的需求。
本論文提出一套高容量的音訊資訊隱藏技術。本技術利用音訊樣本間的差值來嵌入秘密資訊。在嵌入過程中，本技術將掩護音訊內兩兩相鄰的音訊樣本，以不重複選取的方式分成一組，然後計算各組內兩音訊樣本的差值，並依據人類聽覺特性，將所有可能的差值分成數個差距層，製成差值表。秘密訊息的嵌入即是以差值表內所對應到的新的差值來取代原差值。
本方法提供了一套簡單的方式，使得嵌入後的結果比使用傳統最低位元取代法來得更不可察覺。在取出嵌入的秘密訊息時，更不用參照原始的掩護音訊。實驗結果顯示，嵌入後的藏密音訊有很好的不可察覺性及訊噪比值(Signal-to-Noise Ratio)，證明本方法的可行性。

Data hiding is a type of hidden communication. The security, imperceptibility, and high capacity are the main requirements. In recent years, many information hiding techniques have been proposed. But most of the proposed techniques are for digital images. Only a few techniques were proposed for digital audio. This is because that the digital audio is one-dimensional signal which is more sensitive than digital image for human perceptible system. Therefore, it is hard to achieve the requirement of high capacity on constrain of imperceptibility.
This thesis proposes a high-capacity audio hiding technique which uses the difference between two audio samples to embed secret information. In the embedding process, a cover audio is partitioned into non-overlapping pairs of two consecutive samples. The difference value is then calculated from each sample pair. All possible difference values are classified into several intervals to form the difference table according to human auditory character. The secret information is then embedded into the cover audio by replacing the difference value with the new value obtained from the difference table.
The proposed technique provides an easy way to produce a more imperceptible result than those yielded by simple least-significant-bit replacement methods. The embedded secret information can be extracted from the stego-audio without referencing the original cover audio. Experimental results show that the stego-audio has good perceptual transparency and signal-to-noise value. It proves the feasibility of the proposed method.

誌謝 ii
摘要 iii
ABSTRACT iv
目錄 v
表目錄 vii
圖目錄 viii
1. 緒論 1
1.1 前言 1
1.2 研究動機 2
1.3 論文架構 3
2. 文獻探討 4
2.1 資訊隱藏 4
2.2 音訊簡介 7
2.3 人類聽覺特性 9
2.4 音訊資訊隱藏技術回顧 14
2.4.1 音訊資訊隱藏的需求 14
2.4.2 音訊資訊隱藏技術 15
2.5 能量差異資訊隱藏 17
3. 高容量音訊資訊隱藏技術 21
3.1 前言 21
3.2 藏密 23
3.2.1量化差值 23
3.2.2 嵌入資料 25
3.3 取出 28
4. 實驗結果與討論 29
4.1 實驗環境 29
4.2 實驗結果 31
4.3 分析與討論 34
5. 結論與未來研究方向 37
5.1 結論 37
5.2 未來研究方向 38
參考文獻 39
自傳 43

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