An Action States Based Digital Rights Expression Modal Research

As more and more digital contents are being published and delivered via Internet, Digital Rights Management Technology is urgently needed for protecting intellectual property of these digital contents, guaranteeing the legal right and profit of author, publisher, distributor and consumer. The kernel of Digital Rights Management Technology is digital rights expression model.After some existed digital rights expression models were analyzed and compared, a new digital rights expression model based on action states, named as DDRM model, was presented in this paper. DDRM model could not only describe the static relationships among actions, principals, resources, devices and other entities of rights, but also express the action states whose properties include time, number of times, fee and other properties. The action states were used to determine obligations for the principals of these actions. Based on first-order dynamic logic, a logic symbol system, named as DrFDL, was provided for rights reasoning of DDRM model. Finite state automaton was also used to simulate the process of rights reasoning of DDRM model. In order to realize rights validation based on DDRM model, a rights validation algorithm was designed as well as it's complexity of time and space was analyzed. A method about how to eliminate collisions arising from the process of rights validation of DDRM model was also discussed. Based on MPEG REL SDK framework, rights validation system prototype of DDRM model was designed and realized. Some tests were performed in this system finally.Our work is significant for promoting the development of Digital Rights Management Technology and protecting intellectual property of digital products.