A Study on New Techniques for EPUB Document Steganography

[[abstract]]隨著網路的進步與行動裝置的普及，電子書已漸漸取代人們閱讀的習慣，但 也因此衍伸許多電子書的版權問題。EPUB 電子書是目前廣泛被使用的電子書格 式之一。由於電子書的重製與傳播非常容易，為了防止被有心人士任意盜用，本 論文提出兩種資訊隱藏方法用以保護 EPUB 電子書之版權或做秘密傳輸使用。第一種方法利用 CSS 文件之單位轉換，將欲隱藏之機密資訊隱藏在 EPUB 文件之中；第二，利用擬元素特性，將機密資訊做第一階段正整數分解對機密資訊編碼，再利用分解方式做第二階段編碼，將機密資訊嵌入 XHTML 文件中。此兩種方法將機密資訊隱藏於 EPUB 文件後均不會改變電子書的顯示效果，具有高度隱密性。由實驗結果得知，所提之兩種方法皆具有有效性與可行性。 關鍵詞：EPUB文件、CSS檔、單位轉換、擬元素、偽裝學[[abstract]]Following the development of the Internet and the popularity of mobile devices, e-books have gradually changed people’s reading habits; therefore, the copyright issueof e-books has arisen as an important issue. EPUB is one of the most widely usede-book formats. Due to e-books being very easy to reproduce and disseminate, it is necessary to prevent arbitrary misappropriation; this paper proposed two kinds of information hiding methods to protect e-book's copyright and secret transmission. The first is a method in CSS files to hide secret messages in e-books by unit conversion. The second method has two steps, the first part is integer factorizing the secret messages; the second part uses factorization again to encode the secret information into XHTML files. These two kinds of methods hide the secret messages in EPUB files, and will not change the display effects of the e-books, and still maintain strict privacy. According to the experiments, both methods that are proposed in this paper are effective and feasible. Keywords: EPUB file, CSS file, Unit Conversion, Pseudo-elements, Steganograph