Patent ID: 8327136

Claim:
An inter-acting method between a terminal and entities constituting a broadcast network for protecting content in a broadcast environment including the broadcast network and the terminal, the broadcast network having a Broadcast Service Application (BSA), a Broadcast Service Distribution (BSD), and a Broadcast Service Management (BSM), the inter-acting method comprising: transmitting a registration request message for obtaining a group key in a registration process for the terminal from the terminal to the BSM, wherein the group key is encrypted by a public key of the terminal; receiving, by the terminal, a registration response message comprising the group key generated by the BSM through a broadcast channel of the BSD; requesting a service joining process by the terminal; receiving, by the terminal, in response to the service joining request, a message including a Rights Object (RO) corresponding to the content; obtaining a service key by decrypting the RO using the group key, the service key being an encryption key assigned when the terminal joins the service; if a traffic key message is received in the terminal, obtaining a traffic key from the traffic key message by using the service key, the traffic key being an encryption key used for encrypting the content; and receiving and decrypting an encrypted content using the traffic key, wherein the service joining process comprises: when a service joining request message is received from the terminal, generating, by the BSM, the RO using the service key; transferring, by the BSM, a service joining response message including an RO encrypted with the group key to the BSD; broadcasting, by the BSD, the service joining response message to the terminal; and decrypting, by the terminal, the encrypted RO included in the service joining response message using the obtained group key to obtain the RO.