基於秘密共享技術之PDF檔案資訊隱藏技術

Abstract

隨著網路科技與多媒體的蓬勃發展，各項惡意攻擊與威脅也與日俱增，資訊安全性儼然成為重要議題。而秘密共享技術則讓我們可以安全地將秘密分享出去，任何人需要有 k 個 shares 才可以正確還原秘密。本篇論文結合了兩大技術，提出一個能應用在有限資源的共享服務以及團體認證等情境的秘密共享方法。我們根據 Koptyra 等人的概念以及 Shamir 秘密共享方法，提出了一個基於秘密共享的資訊隱藏方法。可以將一段秘密資訊依照指定的共享份數分散到多個 PDF 檔案中，並使用 PDF 隱寫技術進行 資訊隱藏，且不會留下視覺痕跡。由於 PDF 良好的結構性以及使用的共享方法，秘密不易受到攻擊破壞，且若有部分丟失也不至於無法還原秘密，藉此提高了安全性及容錯性。

With the rapid development of network and multimedia, malicious attacks and threats are increasing day by day, making information security an important issue. Secret sharing technique allows us to share secrets safely, and it needs k shares to recover the secrets. In this paper, we combined the two techniques and proposed a secret sharing approach that can be applied in some scenarios such as resource-consuming shared services and group authentication.Based on Koptyra's concepts and the Shamir's Secret Sharing method, we proposed a secret sharing based data hiding method. A secret can be distributed to multiple PDF files according to a specified number of shares, and then can be concealed using PDF-Steganography without leaving visual traces. Due to the good structure of the PDF and the use of the sharing method, the secret isn't easy to be attacked and damaged. If part of shares got lost, it is still possible to reconstruct the secret, thereby improving security and fault tolerance.