文字類型檔案的資訊隱藏技術之研究

Abstract

資訊隱藏是近年來相當熱門的研究議題。不同於密碼學中將機密資訊以密文的方式在雙方之間傳送，資訊隱藏利用將機密資訊隱藏於有意義的掩護檔案裡傳送的方式，用以確保機密資訊不被惡意攻擊者發覺從而進行竊聽或截取。然而，當前的資訊隱藏以影像作為掩護檔案為主要研究方向，不同檔案類型的研究則不多。為了讓不同類型之檔案也可作為掩護之用，目前已有針對word檔與HTML檔的隱藏技術，但其隱藏量則稍嫌不足，且其修改原始掩護檔案之次數也較多。為此，本研究提出了word檔與HTML檔的資訊隱藏方法。根據實驗結果顯示，所提出的方法可以降低修改掩護檔案的次數，並且提高隱藏量。 除了確保機密資訊的安全性之外，檔案的版權歸屬也是相當重要的研究範疇。隨著資訊技術的發達，任何人皆可輕易地複製或擷取部分有意義之檔案作為己用。當前的版權保護以在影像中加入含有擁有者資訊的浮水印為主，並且應避免檔案遭到竄改或破壞後，造成浮水印失真而變得難以識別。不同於影像有多餘的資訊用以藏入浮水印，若欲將浮水印藏入HTML檔案則需提出符合HTML特性的浮水印隱藏方法。為此，本研究提出一種針對HTML檔案的多管道浮水印藏入系統，透過投票機制，即使有些微資訊遺失也能正確擷取出浮水印。

Data hiding scheme has been a popular research issue nowadays. Being different in cryptography, data hiding scheme embeds secret data in meaningful files and transmits between senders and receivers. However, most studies of data hiding focus on image; other files have less research. For the aim of using various files as cover files, several studies which employ word documents and HTML files had been proposed. Nevertheless, these schemes have less capacity and the time of modifying spaces could be decreased. In this study, data hiding scheme on word documents and on HTML files are proposed, respectively. According to experiment results, the proposed schemes are better than other schemes in capacity, and the time of modifying is less as well. It will be appropriate for data hiding on word documents and HTML files. In addition to data hiding, we also present a novel watermarking scheme for HTML files in this study. The proposed scheme hides watermark simultaneously with some hiding schemes, that is, multi-channel system, in the cause of the purpose of watermark. Furthermore, a voting phase will execute as we extract the watermark. It can assure that the extracted watermark is more similar to original one.