隨著現代科技的快速發展，數位多媒體已經相當普及且隨處可見，透過這些多媒體，我們隨時隨地都可以觀看影片、聽音樂或是閱讀書報，多媒體已經儼然成為我們生活中不可或缺的一環；然而，多媒體帶來的便利也讓盜版變得更加猖獗，例如：我們可以很容易地上傳一部有版權的影片，但卻沒有得到作者的同意，作者及出版商們非常渴望能夠保護他們的智慧財產權或是商業利益，因此，數位版權管理系統因應此種強烈的需求而出現了，數位版權管理是一系列用來限制數位多媒體檔案存取的技術，雖然目前市面上有許多企業級的數位版權管理系統，但這些系統皆無法百分之百地滿足我們的需求，也無法根據這些需求做客製化的修改，有鑑於此，我們設計了一個客製化的數位版權管理系統，這個系統可以限制使用者只能在授權的時間內在授權的設備上播放多媒體檔案，此數位授權管理系統採取了一系列安全有效率的加解密演算法，包括AES、SHA-256以及RSA，我們也將此系統移植到其它作業系統，如：Windows、Android和iOS，除此之外，我們也將系統功能模組化，以便未來開發及維護，在低階設備中，通常性能不如個人電腦，我們藉由改變加密金鑰的長度或是加密的密度來達到提升執行速度的目的，此外，我們也解決了因為隨機訪問檔案產生的遮罩移位問題，最後在我們的分析中證明了此數位版權管理系統有高安全性，在一般設備中執行也都有良好的效能表現。;With the rapid development of technology, digital multimedia has been widely utilized. Accesses of multimedia contents become a daily routine. Although multimedia brings ease and convenience on content sharing, it also makes piracy more feasible. For example, it is easy to upload a copyrighted video to YouTube without the owner’s permission. Authors and merchants are dying for protecting their intellectual property and commercial profits. Digital Right Management (DRM) systems are provided to fulfill the desire. DRM is a collection of techniques used to control access to copyrighted materials. Since current enterprise DRM solutions are not allowed for customized modification, they cannot fit in our considered scenario perfectly. As a result, we proposed a secure DRM system with a design on user demands, where a consumer can access contents only on authenticated devices until the authorization expires. Our DRM scheme involved a series of robust cryptosystems including AES, SHA-256 and RSA. Applications as DRM agents are implemented on Windows, Android and iOS platforms. Moreover, we modularized the DRM components for easy extension and integration. For better performance on low-end devices, parameters of encryption are introduced, namely, the key size and the encryption density. We addressed the Mask Shift Problem caused by random access and implemented the device identifier acquirement. The DRM system are also proved to have high security and nice performance in our analysis.
