- 學位論文
數位音訊之時域特徵零浮水印研究
TIME-DOMAIN FEATURES-BASE ZERO-WATERMARK FOR DIGITAL AUDIO
摘要
由於網際網路的普及性，許多的資訊如音訊與影像等，皆以數位化的方式存放在個人電腦與網際網路上，導致各種數位化資訊透過網際網路，變得容易取得與竄改。因此，為了保護擁有者的智慧財產權，在數位資訊中嵌入數位浮水印（Digital Watermark）就是其中一種重要的方法。傳統的浮水印技術不論是時間域(Time Domain)或頻率域(Frequency Domain)的做法，皆會有兩個無法解決的問題。一是資訊加入浮水印後，所造成的資訊品質降低，二是浮水印的強健性和不可察覺性彼此無法兼顧。為解決上述問題，近年來有學者提出零浮水印（Zero-watermark）機制。由於零浮水印的作法是將浮水印與數位資訊特徵做結合，而非數位資訊本身嵌入浮水印，所以被保護的資訊與原始資訊完全相同。也因此在實務應用上，必須有一個第三公正機構針對秘密金鑰做時戳認證，藉此來了解浮水印的認證時間與擁有權。 本論文將零浮水印的概念應用在音訊中，提出幾種在時間域上的特徵加密方式，而這幾種方法都有個共通點：容易執行、加密迅速。本文所提出的方法皆必須先分割音訊，使音訊分成數個相同大小的音框後，再以不同方式去判斷此音訊的特徵。 實驗結果顯示測試音訊經過各種攻擊方式，如重新取樣、重新量化、各種Filter攻擊、MP3壓縮、加入白雜訊、刪除音訊等，本文所提出的方法仍然能有效還原出可辨識之浮水印圖像。由實驗結果顯示不需要用太過複雜的特徵萃取方式，也能有相當好的還原效果。實驗結果也符合數位浮水印的技術需求，如透明性、強健性、安全性、明確性和還原浮水印時不需要原始音訊輔助。
並列摘要
According to the development of the Internet, a lot of digital information conserves to computer and internet, the digital data is easy to copy and recondition by internet. Therefore, the authors protect their Intellectual Property Rights, The embedding of digital watermark into multimedia content has been proposed to deal with this problem. In traditional watermarking algorithms, the insertion of watermark into the host signal inevitably introduces perceptible quality degradation and the inherent conflict between imperceptibility and robustness. Zero-watermarking technique was proposed to solve these problems successfully. This scheme extracts some essential characteristics from host signal and uses them for watermark detection instead of embedding watermark into original signal. In actual applications, the secret key which was constructed after the zero-watermarking schemes should be assigned a time stamp by authority authentication department. In this paper, we application zero-watermarking technique for digital audio, we propose three zero-watermark schemes to search the digital audio characteristics in time domain. The schemes have some character, they are easy to execute and encryption very fast. Simulation results show that our schemes can get the embedded watermark back after taking several attacks, and experiments show that the recovery performance of high sampling rate audio which used the method C can have excellent efficiency. The Simulation results satisfy the digital watermark technical properties of transparency, robustness, unambiguity, security, and blindness.