Patent ID: 8234493

Claim:
A method of transmitting content to a user device from a home server in a home network, the method comprising: transmitting the content, which is encrypted by using a predetermined content key, and transmitting the predetermined content key, which is encrypted by using a pair of a predetermined session public key and a session private key, to the user device, wherein the content that is transmitted is bound to a user by allowing transmission of the content from the user device to a first user device only if it is determined that the first user device belongs to the user by using a user public key and a user private key of the user to whom the home server belongs, wherein the user public key and the user private key are used to determine whether users of a plurality of user devices in the home network are identical, wherein the session public key and the session private key, used by the plurality of user devices in the home network, are updated if the user device leaves the home network.