Study On Formal Model Of Digital Right Expression Language And Its Application

Digital Right Expression is the core concept of DRM (Digital Right Management) as well as the most complicated problem. It contains the balance and interest game around obligation and right between each stakeholder who is involved in the DRM system. Our research is concentrate on above topic. And to solve the problem of how to express the right clearly and accurately, we propose a model of Extended Digital Right Expression Language (EDREL). Furthermore, we introduce the methods of domain engineering, software engineering and formal method, and look into the application domains from top to down with successive refinement; meanwhile we discuss and analyze the syntax, semantic and the pragmatic of EDREL in two application domains. Our work is concentrated as follows:1. Introduce the method of domain engineering to specify and analyze the application domain of DRM, propose an EDREL model. This model is different from the current DREL models mainly as following points:(1) our EDREL model can describe both licenser and licensee of the right, so it’s easy for right recursion while problem happen;(2) our model adds formal model support to describe the sub-licensing and right re-distribution;(3) in our model, the concept of license is expressed the obligation and permission as well as describe the action on digital content in all life-cycle, so that the EDREL model can be applied into other application domains.2. Introduce RSL and OTS/CafeOBJ to describe EDREL model formally, and formal analyze the properties, which based on EDREL model. Comparing with the current formal research around this area, our innovations are:(1) the OTS model method makes the current single trace-based license behaviors description into multiple trace-based;(2) add CafeOBJ description to describe deontic and temporal logic, and based on the CafeOBJ specification, the CafeOBJ thermo prover can analyze some properties about the license automatically;(3) apply the deontic and temporal logic to describe right expression and its properties, discuss how to use OTS/CafeOBJ method to describe right expression language, and the problem such as:validation, effective condition, time sequence and so on.3. Apply the EDREL idea and methodology into e-government document processing domain, and give the instance and formal analysis of the EDREL model in this application domain. Furthermore, we comparing the changes of timely property before and after introduce the EDREL idea, based on our formal specification and analysis.4. Apply the EDREL idea and methodology into XBRL GL based accounting information discoursing domain, propose an Accounting Digital Right Management Expression Language to express the obligation and permission between accounting information publisher and user, to reduce the risk of accounting secrete information leakage under semantic web environment.