For Digital Rights Management System Design And Implementation Of A Set-top Box

In recent years, with the rapid development of Internet, the idea of using Internet to watchTV comes up. STB (Set Top Box) as a high-tech product that integrates computer, television andtelecommunication technology, is gradually integrating the functions of computer to television.STB as a multi-functional service platform speeds up the progress of this dream, it makes digitalproducts more and more popular at the same time. However, digital products’ characteristics ofbeing free to copy and re-distribution make Internet become the breeding ground wherecopyright media contents can be illegally used and released. This threatens the legitimate rightsof the content providers, distributors, operators and consumers. The appearance of digital rightsmanagement technology solves this problem. DRM can strengthen the security of digital content,prevent the illegal copying and releasing and protect the copyrights.This thesis based on the OMA DRM2.0standard, after referring to a variety of DRMprotection technology and scheme, propose a new security model of DRM for STB. In thismodel content object and rights object are separated respectively, and the content object isencrypted by content encryption key, while rights object is encapsulated by user’s device relatedkey. To ensure the legitimacy of the user and the server, mutual authentication is realized forusers’and server’s trust management.A DRM system is implemented using this model to verify its effectivity. When encrypting,it doesn’t require analysis the process of media contents’ encoding and decoding, only encryptsthe files in structure, which makes this system support for multiple media file formats. For thisreason, this system successfully achieves decryption playback at a specified position from client.When decrypting, the ciphertext is read from the harddisk of STB, but the decrypted plaintext isnot written back to the harddisk. Owing to the plaintext only exists in memory, it won’t be leakedin client. Keys and algorithms are stored, using different design strategies in key managementserver and security engine separately, which can not only improve the security of the system, butalso improve the efficiency of the system. Open Digital Rights Language is used to design thelicenses which support hardware binding, obtaining license directly or indirectly, media contents’copy and licenses’transfer.When designing this system, we follow the principle of safety, practicality and low coupling.At the end of the thesis, we analyze the system’s performance. The experiment results manifest,using technologies of cryptography, digital signature and authority management to controllingthe use of High Definition contents, MTV, TV Media Magazines, this system is secure, reliableand efficient for content protection, authentication, license management and user experience.