Abstract: In an electronic apparatus control system provided with: a plurality of electronic apparatuses connected to a network covering a predetermined area; and a controller for controlling these electronic apparatuses, the controller (11) is provided with: a generating device for generating a group key peculiar to the network (18) in order to encrypt the information flowing through the network (18); and a wireless unit (21) for transmitting the generated group key to a plurality of the electronic apparatuses. The electronic apparatus is provided with: a memory device for storing the group key transmitted; an encrypting device for encrypting the information flowing through the network (18) using the group key; and a decoding device for decoding the encrypted information using the group key.

Abstract: In an electronic apparatus control system provided with: a plurality of electronic apparatuses connected to a network covering a predetermined area; and a controller for controlling these electronic apparatuses, the controller (11) is provided with: a generating device for generating a group key peculiar to the network (18) in order to encrypt the information flowing through the network (18); and a wireless unit (21) for transmitting the generated group key to a plurality of the electronic apparatuses. The electronic apparatus is provided with: a memory device for storing the group key transmitted; an encrypting device for encrypting the information flowing through the network (18) using the group key; and a decoding device for decoding the encrypted information using the group key.

Abstract: An optical disc is constituted by a recording region for recording contents data, a readout region, and a protect region for recording copyright data of the contents data in this order from an inside. Access cannot be obtained to a groove track outside the readout region except that legal reproduction and recording is performed, and the groove track records a part of contents key data used for encrypting and decoding contents data.

Abstract: Recording information is recorded after adding reproducing limit information for controlling the number of reproducing times to the recording information and embedding the identical reproducing limit information thereon separately from the above in a way of preventing illegal detection. Then, after confirming a coincidence between the reproducing limit information added and the reproducing limit information embedded, the recording information is controlled to be supplied to an external source according to the same reproducing limit information.