The selling and buying of digital products via Internet not only saves business cost and time, but also makes it possible for us to control the usage of media remotely by the interaction between the client and server. The digital content is encrypted and packed with the client controller program into an all-in-one package. When the client opens the package, controller program starts to run, accessing server to fetch content decryption key and informing the server the status of player. Since the unique PC hardware fingerprint is registered on the server via Internet at media purchase stage, only the same computer can pass the identity authentication. In this way, we bind one specific digital asset with a specific client device, preventing the media from abuse.