近年來數位科技的快速發展引領了數位多媒體的普遍使用，此外行動裝置的使用者數量也大幅增加中，因此多元化的多媒體服務廣泛出現在行動應用當中。多媒體內容的廣泛應用帶給人們更多的享受與便利性，但也很容易遭受到不法的使用、複製、散佈與竄改。之前許多針對行動環境的研究，提出的數位版權管理系統大多數存在著安全性與效率性的妥協、針對特定影音格式的加密等等。然而今日行動裝置的運算能力越來越好，高效能的行動裝置也越來越普及。因此我們可以在合理的效能下，提高系統的安全性。在本篇論文中，我們提出了一個在行動應用中針對多媒體內容且易於實現的數位版權管理系統來有效防範非法地使用與散佈。在我們的加密方法中，利用亂數與位置概念於資料區段加密來達到良好的安全性。並在版權文件中實現了針對特定裝置的數位簽章，來保護多媒體內容不被任意散佈。Rapid developments in digital technologies have led ubiquitous access to digital multimedia. It brings people wide use of multimedia content in various mobile applications. The evolution makes pirates easy to copy and use multimedia content and products illegally. In previous encryption scheme of DRM systems for mobile devices, there were existing trade-off between performance and security. However, nowadays computational capability of mobile devices grows much stronger, and more and more high-performance mobile devices are widely used. Therefore we can focus on the security level of encryption scheme. In this thesis, we propose a new DRM system which can be implemented easily in mobile applications in order to prevent multimedia content from illegal distribution and copying. We use a block cipher with the concept of rand seed and position seed to enhance security level, and also devise the device-dependent certification in the license file by using DSA for the digital signature to prevent illegal distribution.
