Watermark data hiding apparatus, a method of hiding watermark data, a method of transmitting data including watermark data, a recording medium storing data including watermark data, a data and watermark data reading apparatus, and a method of reading data and watermark data

Abstract

The error detection code adding circuit adds error detection codes to watermark data. An encrypting circuit encrypts the error detection code added watermark data according to a first password. N encoders hide (embed) the encrypted error detection code added watermark data in the content data by N different hiding algorithms, respectively. A selector selects one of N encoders in response to a selection signal and outputs the encoded and selected content data in which the encrypted error detection code added watermark data is hidden. N decoders read watermark data and the error detection codes from the encoded content data by N extracting algorithms corresponding to the N hiding algorithms, respectively, to output N extracted content data including N read watermark data and N error detection codes and N read watermark data, respectively. Decrypting circuits decrypt the N read watermark data and the N error detection codes from the N encoders according to a second password corresponding to the first password, respectively. The error detecting circuits for detecting errors in the N error detection codes, respectively. The selector selects and outputs one of the N extracted (inverse-hidden) contents data according to the detected errors.