利用MPEG-21 REL實現數位影像廣播系統中的數位內容保護

Abstract

在數位電視中，條件式存取(Conditional Access)提供了設定存取限制的方法。但是一般的條件式存取系只能對數位內容提供存取的限制，並無法更進一步地對接收到的內容之使用權限做保護及控管。本論文的目的是利用MPEG REL在數位電視系統上實現條件式存取以及權限管理。證明可以使用MPEG REL作為數位影像廣播系統(DVB)以及數位權限管理系統(DRM)的橋樑。在本論文中，我們把MPEG REL的License放入至DVB-SI中廣播出去，使接收端可以根據收到的License來控制使用者的使用權限。於是我們設計了兩個應用系統來證明透過廣播MPEG REL的License不僅可以做到條件式存取還可以達到權限管理的功能。另外，在我們的應用中為了達到存取限制，還設計了一個金鑰管理機制。

In a digital TV system, the Conditional Access (CA) system is essential to protect digital contents from unauthorized use. However, an ordinary CA system has only the ability to restrict the access to certain material. It cannot provide a further protection and prohibit unauthorized uses after the content has been downloaded and descrambled. The goal of the thesis is to use the MPEG REL to implement both the CA and the rights management systems. We will show how one can use the MPEG REL to bridge the gap between a DVB system and a DRM system. In this thesis, we insert a license, according to MPEG-21 REL expressions, into the Service Information of a DVB bit stream. With this license, the operators can constrain the user’s operations on the content through the DRM system and the smart card. To demonstrate the method we propose, we implement two application examples to show that using the REL can achieve both conditional access protection of digital content and manage the utilization of digital assets. In addition to the usage control of the MPEG REL, we also propose a key management machine in our applications to protect the content from being illegal accessed.