Improved VoIP Real-time Speech Hiding Based on Discrete Cosine Transform

[[abstract]]在網際網路資訊傳遞中，監聽者想竊取訊息內容是一件不難的事情。因此使用資訊隱藏技術將重要的秘密音訊隱藏在VoIP(Voice over Internet Protocol)即時通話中，是一種極佳的保護機制。藉由這種保護方式，令監聽人員無法察覺聽似普通的語音通話中有秘密音訊，頂多只會在通話中感覺到些許的雜音。比起僅將通話內容加密，是更進階的保護方式。 本論文提出一個可以將重要的秘密音訊以離散餘弦轉換方法隱藏於即時網路電話G.711編碼頻域係數中之技術，不僅可以防止重要通話被竊聽並且可以有效躲避RS(Regular and Singular)資訊偵測的技術。[[abstract]]Communication is easy to be eavesdropped as it travels on the Internet. Therefore, steganography is a good solution to protect important Voice over Internet Protocol (VoIP ) conversations. By this mechanism, eavesdroppers may only feel there are some noises in a VoIP call, but will not notice an important secret conversation is hidden in that call. In this thesis, we propose a method for voice hiding in a real-time communication system using the G.711 codec. The proposed method applies Discrete Cosine Transform (DCT) to hide a secret conversation into frequency coefficients which could prevent eavesdropping and resist Regular and Singular (RS) steganalysis.[[note]]碩