Contents service providing method and authentication method between device and device using broadcast encryption, display device and device for low resource

A contents service providing method using the broadcast encryption and an authentication method between devices are provided to perform the authentication between the devices by decoding the encryption information using the confidential key set. The contents service offering method using the broadcast encryption is as follows. The small source device transmits its own ID to a playing component(S201). The playing component receives and stores the MKB(Media Key Block) and the revocation list from the server. The playing component extracts the encryption information from the MKB based on the ID and the revocation list and transmits to the small source device. The small source device receives the encryption information from the playing component(S202). The small source device decodes the encryption information by using the confidential key set(S203).