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

A method of hiding watermark data in content data comprising the steps of:

• adding error detection codes to watermark data to generate error detection code added watermark data;
• encrypting said error detection code added watermark data in accordance with an inputted password;
• hiding said encrypted error detection code added watermark data in said content data by different hiding algorithms, respectively;
• and
• selecting one of different hiding algorithms in response to a selection signal to output said encoded and selected content data in which said encrypted error detection codes added watermark data is hidden by said selected one of different hiding algorithms.

A method of transmitting content data including watermark data comprising the steps of:

• adding error detection to watermark data to generate error detection code added watermark data;
• encrypting said error detection code added watermark data in accordance with an inputted password;
• hiding said encrypted error detection code added watermark data in said content data by different hiding algorithms, respectively;
• selecting one of different hiding algorithms in response to a selection signal;
• and
• transmitting said encoded content data in which said encrypted error detection code added watermark data is hidden by said one of different hiding algorithms.

A recording medium comprises:

• a substrate;
• and
• a data storing layer for storing content data, watermark data, and error detection codes of said watermark data, wherein said error detection codes are added to said watermark data to generate error detection code added watermark data, said error detection code added watermark data is encrypted in accordance with an inputted password;
• said encrypted error detection code added watermark data is hidden in said content data by different hiding algorithms, respectively, one of different hiding algorithms is selected in response to a selection signal, and said content data in which said encrypted error detection code added watermark data is hidden by said selected one of different hiding algorithms.

A watermark data reading apparatus, wherein said watermark data is attached with error detection codes, said watermark data and said error detection codes are encrypted in accordance with a first password and said watermark data, said error detection codes are hidden in said content data by one of N different hiding algorithms selected in response to a selection signal to output said encoded content data in which said error detection code and watermark data is hidden by said selected one of N different hiding algorithms, N being a natural number more than one, said watermark data reading apparatus comprising:

• reading means for reading said watermark data and said error detection codes from said encoded content data by N extracting algorithms corresponding to said N hiding algorithms, respectively, to output N sets of extracted content data including said read watermark data and said error detection codes;
• decrypting means for decrypting said N read watermark data and said N error detection codes from said reading means in accordance with a second password corresponding to said first password, respectively;
• detecting means for detecting errors in said N error detection codes from said decrypting means, respectively;
• and
• selecting means for selecting and outputting one of said N extracted content data in accordance with said errors.

A method of reading content data and watermark data hidden in said content data, wherein said watermark data is attached with error detection codes, said watermark data and said error detection codes are encrypted in accordance with a first password and said watermark data, said error detection codes are hidden in said content data by N hiding algorithms, respectively;

• one of N hiding algorithms is selected in response to a selection signal to output said encoded content data in which said error detection code and watermark data is hidden by said one of N hiding algorithms, N being a natural number more than one, said method comprising the steps of:
• (a) reading said watermark data and said error detection codes from the encoded content data by N extracting algorithms corresponding to said N hiding algorithms, respectively, to output N extracted content data including said N read watermark data and said N error detection codes;
• (b) decrypting said N read watermark data and said N error detection codes in step (a) in accordance with a second password corresponding to said first password, respectively;
• (c) detecting errors in said N error detection codes, respectively;
• and
• (d) selecting and outputting one of said N extracted contents data in accordance with said errors detected in step (c).