Abstract: The present invention provides an electronic device that decodes, through simple procedures, content encoded within a preset time period. The electronic device comprises: a tuner 1, a CAS (Conditional Access System) client 2, and a renderer 3. The CAS client 2 comprises: a control unit 21, a timing unit 22, and a decryption key generating unit 23. The timing unit 22 and the decryption key generating unit 23 are disposed in the CAS client 2; as a result, a preview operation can be easily performed without sending elapsed time information from the renderer 3 to the CAS client 2.

Abstract: The present invention provides an audiovisual access criterion updating method, for updating an audiovisual access criterion in an audiovisual access criterion managing device, the audiovisual access criterion managing device managing the audiovisual access criterion of a content signal, the audiovisual access criterion updating method includes: a step of receiving update information descriptive of update content of the audiovisual access criterion and identification information of the audiovisual access criterion managing device by an updating code generating system; a step of generating an updating code by the updating code generating system according to the update information and the identification information; a step of receiving the updating code by the audiovisual access criterion managing device; and a step of updating the audiovisual access criterion by the audiovisual access criterion managing device according to the updating code.

Abstract: A playback management device (3) is provided for use with a receiver (2) for receiving a content signal encoded by a key (Ks) updated in a specified update period and first control information (ECM) obtained by encoding information about the key (Ks) and a playable time (Tpre) for the encoded content signal. The playback management device (3) includes: an interface (31) for collecting the first control information (ECM) from the receiver; a first decoding portion (34) for decoding the first control information (ECM) and thereby restoring the key (Ks) and the playable time (Tpre) for the encoded content signal; and a control portion (35) for determining, according to the playable time (Tpre) for the encoded content signal and the update period (Tud) for the key (Ks), whether to output the key (Ks) to the receiver (2), and outputting the restored key (Ks) to the receiver (2) when determining to output.