隨著科技越來越進步，數位內容的複製和傳播也越來越容易了。特別是p2p軟體的風行,使得檔案的搜尋越來越簡單，下載的速度也越來越快。嚴重危害到數位內容業者的利益，也違反了智慧財產權法，更遏阻了數位內容產業的發展。此時，數位版權管理(Digital Rights Management)系統被提出來解決這些問題。
數位版權管理系統，雖然提供了基本的權限管控，但很多傳統市場上的使用習慣，例如: 權限的移轉，合法的修改，交易時的隱私權保護 等等, 都還沒有完善的解決方案。這些大大減低了消費者購買受保護的數位內容的意願。
在本研究中，藉著在伺服器端提供權限轉移的功能，我們解決了其中一個關於”公平使用”(fair use)的爭議，購買的數位內容可以借給朋友。基於這個新功能，我們更提出在電子商務中兩個新的商業模式: 一個是AV (Au-dio/Visual)出租店－消費者可以在線上租用數位內容，另一個是AV二手商店－消費者可以轉賣他們曾經購買的數位內容。這兩個商業模式，使得我們的數位產權管理系統更加合理而且合法。
再者，我們也對數位產權管理系統作了概括的介紹，從其分類，基本架構，到需要注意的安全性議題。也有對其作一些合法性的探討和市面上一些系統的概況。

With the improvement of technology, the duplication and distribution of digital contents is getting easier and easier, and the population of peer-to-peer software makes searching easier and downloading faster. This decreases the bene-fits of content providers, violates the copyright laws, and restrains the development of the digital content market. Therefore, DRM (Digital Rights Management) sys-tems are proposed to resolve these problems.
Although DRM systems prevent digital contents from unauthorized access, it is insufficient to provide the functions which are associated with “personal use” and “fair use”. For example, allowing transfer of rights, allow excerpting and modification, and promoting user’s privacy. These lower the desire of consumer’s demand of purchasing the contents with DRM mechanism.
In current Digital Rights Management systems, consumers cannot resell copyrighted contents arbitrarily. This violates the common use of property in the real world. In this thesis, we solve this problem which is associated with the fair use issues by providing a new function of changing access right in DRM system. Based on this new function in DRM system, we propose two new business models in Electronic Commerce. One is an AV (Audio/Visual) rental store in which custom-ers can rent audio/visual media on-line. The other one is an AV secondhand store in which customers can resell audio/visual media they purchased to others. These two new business models make our transferable DRM system reasonable and legal.
In addition, we will introduce the DRM systems from the categories to the security issues and a typical architecture to acquire a basic cognition of DRM systems. Furthermore, we will address the fair use and legal use of DRM systems, and we will show the overview in the current market.

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