Fecha de publicación: 20/11/2001 Fuente: Wipo "digitalization" Copying of digital data from a digital recording medium is controlled so as to prevent unauthorized copying. The digital data is transmitted from a transmitter-side apparatus to a receiver-side apparatus through interfaces thereof in a system of a plurality of digital apparatuses connected to each other through a bus and mutually authenticated. The interfaces permit transmission and receiving of the digital data only between the authenticated apparatuses. Copy control information indicating a copy restriction level is added to main data of the digital data recorded on the digital recording medium such that the main data contains a first portion containing at least one of picture information and voice information, and a second portion containing the copy control information. Electronic watermark information is added to the second portion of the main data. An error correction code is added to the main data, and then intentional error information having a particular pattern is added to the digital data. The reproducing and recording operations of the transmitter-side apparatus and the receiver-side apparatus are restricted with respect to the digital data in the digital recording medium, depending upon whether the digital recording medium is authorized one or not, which is determined based on the copy control information, the electronic watermark, and the error information.