在現今數位多媒體蓬勃發展的情況下，以及多媒體行動裝置的使用者數量也以非常快的速度增加中。因此數位多媒體檔案便很容易遭受到不法的複製和散布，這些非法的行為都會伴隨檔案創造者著作權的問題和許多涉及數位多媒體本身所具有的經濟價值之議題。也因此衍生出了許多數位多媒體檔案的保護機制，並稱之為數位版權管理系統，其功能不乏對多媒體檔案做加密處理、使用簽章檔案來限制多媒體檔案的使用權限等等。在先前，許多針對數位行動環境所研發出的數位版權管理系統幾乎都有著安全性和效率性不可兼顧的問題。然而近年來行動裝置的硬體運算能力日漸增強，高效能的行動裝置也越來越普及。所以我們針對中高效能的行動裝置設計出一套高安全性及高效率的數位版權管理系統，基於我們先前的研究，除了延續使用高安全性的區塊加密演算法，我們另外加入了金鑰轉換引擎來保護加密金鑰。我們也運用了數位簽章的技術來保護授權文件的安全，最後，我們將解密時讀取的區塊增大，從而實現了更有效率的解密機制。 The distribution of multimedia content involves the lawful rights of content owner and the economic value to the content provider, which there are lots of content protect issues around, such as preventing illegal copy and redistribution. And now the mobile device which has capability to play multimedia content becomes popular, and most of them have networking ability that allows them to access contents without computers. Accordingly, there were a few Digital Right Management system (DRM system) designed for mobile devices, yet the trade-off between performance and security exist in those previous studies. However, the capacity and capability of mobile device grows much wider, even dual-core CPU or quad-core CPU attaches on the devices, therefore, we aim on developing such a new designed DRM system on dual-core CPU devices with a high security and reasonable cost. We adopt a block cipher with manipulating the position of the file to enhance the security level also we provide fast and accurate license verification by using RSA digital signature technique, and last, we expand the buffer reading size while decrypting and observe significant performance improvement in varying decryption settings.
