Abstract: A multiple registration system of using the same account for a user to register different devices to a DRC (digital right certificate) server for further downloading a digital content from the network is disclosed. The system comprises a first device, which includes a first reader and a first device identity code, a second device, which includes a second reader and a second device identity code, and the DRC server. The first device and the second device can build connections with the DRC server through the network. The DRC server is for providing the first or/and the second device to apply an account and to use the same account for further downloading the digital content. During registration, the reader stores the account and an identity code of its own device in its own right record file.

Abstract: A digital rights management server (DRM server) exchanges information with at least one electronic document retail server and at least one terminal. A registration procedure and a purchasing procedure are provided. The registration procedure includes: (a) downloading a reading application program into the terminal, which enables authorization by the DRM server of a legal user and a legal terminal; and (b) the DRM server generating an ID code for the legal user and sending the ID code to be stored in the legal terminal.

Abstract: A method prevents illegal copying of an electronic document in a computer system. The computer system has a server for connecting to a plurality of terminals via a network. Each terminal has a terminal identification code for identifying the terminal, and each terminal is capable of requesting an electronic document from the server via the network. The server is capable of encrypting original plaintext of the electronic document to a corresponding ciphertext. The ciphertext is capable of being transmitted to the terminal via the network and being decrypted to the original plaintext. The method has a registration process and a document request process.