Research On The Modeling Of Digital Content Protection And Its Implementation

With the development of computer and network technology, there are more and more applications of digital contents which are easy to be copied, modified and spread. Because of these features, the digital contents are also always under the risk to be filched, juggled, accessed without authorization and illegally distributed. The digital contents can hardly be protected effectively in the network environment due to its large-scale disordered distribution, which has hindered the development of the applications based on the digital contents. Therefore, the research on the protection of digital contents has drawn great interests from both the industrial and academic communities. It has already become a hot spot in scientific study. This paper is mainly intended to address Information Content Security issues. Although remarkable achievements have been fulfilled in this field, we still cannot find an outstanding solution to current research deficiencies: the dominant protection model in many applications can't ensure security for whole lifecycle; little attention is paid to the differences in various application areas of digital contents, while each area has unique requirements; the existent protection model cannot provide all life-long tracing and embedded-protection. So how to implement high-quality, whole-life-cycle protection for digital contents is the focus of this paper.Aimed at improving the deficiency of current research, a formalized analysis is conducted on the activities throughout the lifecycle of Digital Content and the key phases in that cycle are determined with the help of Petri-Net( a typical system describing & analyzing tool). On this basis we put forward Content Lifecycle Protection Concept (CLPC), which mainly employs 'Box' to encapsulate content so that management and protection is applicable in each phase of the lifecycle. A relevant Content Lifecycle Protection Model (CLPM), which divides the whole lifecycle protection of digital content into 4 phases, is provided to deduce the security threats in each phase. CLPM covers the whole lifecycle of digital contents, and is featured with life-long tracing and embedded-protection to complement and enhance current protection models. The key problems with CLPM are how to resolve the Security-Rule collision brought by embedded protection and how to select the appropriate protection mode according to the context. We put emphasis on these two problems: for Security-Rule collision we extended XrML to ExrML which could analyze the root of security rules collision, Security Rules Collision Detecting (SRCD) algorithm and consistent Security Rules Creation(CSRC) algorithm are relatively proposed; for the second problem we uses flexible, multi-feature CLPM mode system to improve the deficiencies of current fixed protection mode.The contributions of this paper can be concluded as followings:1. A Concept of whole lifecycle protection on digital content (CLPC) is proposed on the basis of formalization of activities through out the lifecycle of digital content protection;2. Based on CLPC, a whole lifecycle protection model of digital content - CLPM is brought up. It supports the life-long protection of digital content. And it enables life-long tracing of distribution and usage which helps to locate the root of invalid operation so that...