A storage device formed of a hard disk stores a search table including an index object, a start time stamp, an end time stamp, a decryption start point correlated with index object, and a GOP location offset correlated with index object. Decryption start point indicates a decryption start point for a block including audio and video data broadcast in synchronization with an object and GOP location offset indicates an amount offset between a decryption start point and GOP's random access point.