Copy-guard system and information recording medium used in the same system

A copy-guard system comprising:

• first decoding means for decoding digital data, which is encoded and error-correction-coded by a product code, from an information recording medium in which key information encoded for the digital data is recorded;
• first acquisition means for acquiring digital data encoded and error-correction-coded by an inner code when the digital data decoded by the first decoding means is error-corrected by an outer code;
• detection means for detecting an error position and an error symbol value of the digital data acquired by the first acquisition means;
• identification information detection means for detecting an identification information that is replaced with a part of the digital data encoded and error-correction-coded by the inner code based on the error position and the error symbol value detected by the detection means, wherein the identification information represents whether the information recording medium is original or copied;
• first determination means for determining whether a copy of the information recording medium is protected based on the identification information detected by the identification information detection means;
• and
• copy protection means for protecting a copy of the information recording medium based on determination results of the first determination means.

A copy-guard system comprising:

• first decoding means for decoding digital data, which is encoded and error-correction-coded by a product code, from an information recording medium in which key information encoded for the digital data is recorded;
• first acquisition means for acquiring digital data encoded and error-correction-coded by an inner code when the digital data decoded by the first decoding means is error-corrected by an outer code;
• first detection means for detecting a first error position and a first error symbol value of the digital data acquired by the first acquisition means;
• second acquisition means for acquiring digital data encoded by error-correcting the digital data, which is acquired by the first acquisition means, by the inner code;
• second detection means for detecting a second error position and a second error symbol value of the encoded digital data acquired by the second acquisition means;
• identification information detection means for detecting an identification information that is replaced with a part of the digital data encoded and error-correction-coded using the product code based on the first error position and the first error symbol value detected by the first detection means and the second error position and the second error symbol value detected by the second detection means, wherein the identification information represents whether the information recording medium is original or copied;
• first determination means for determining whether a copy of the information recording medium is protected based on the identification information detected by the identification information detection means;
• and
• copy protection means for protecting a copy of the information recording medium based on determination results of the first determination means.

A copy-guard system comprising:

• first decoding means for decoding digital data, which is encoded and error-correction-coded by a product code, from an information recording medium in which key information encoded for the digital data is recorded;
• identification information detection means for detecting an identification information that is replaced with a part of the digital data encoded and error-correction-coded using a product code based on the error position and the error symbol value detected by the detection means, wherein the identification information represents whether the information recording medium is original or copied;
• first determination means for determining whether a copy of the information recording medium is protected based on the identification information detected by the identification information detection means;
• and
• copy protection means for protecting a copy of the information recording medium based on determination results of the first determination means.

A copy-guard system comprising:

• first decoding means for decoding digital data, which is encoded and error-correction-coded, from an information recording medium in which key information encoded for the digital data is recorded;
• encoded digital data acquisition means for acquiring digital data encoded by error-correcting the digital data decoded by the first decoding means;
• detection means for detecting an error position and an error symbol value of the encoded digital data acquired by the encoded digital data acquisition means;
• second decoding means for decoding the digital data acquired by the encoded digital data acquisition means;
• extraction means for extracting positional information of an identification information, which is embedded in the digital data decoded by the second decoding means, as watermark data;
• identification information detection means for detecting the identification information that is replaced with a part of the digital data encoded and error-correction-coded based on the error position and the error symbol value detected by the detection means and the positional information of identification information extracted by the extraction means, wherein the identification information represents whether the information recording medium is original or copied;
• determination means for determining whether a copy of the information recording medium is protected based on the identification information detected by the identification information detection means;
• and
• copy protection means for protecting a copy of the information recording medium based on determination results of the determination means.

A copy-guard system comprising:

• decoding means for decoding digital data, which is encoded and error-correction-coded, from an information recording medium in which key information encoded for the digital data is recorded;
• encoded digital data acquisition means for acquiring digital data encoded by error-correcting the digital data decoded by the decoding means;
• detection means for detecting an error position and an error symbol value of the encoded digital data acquired by the encoded digital data acquisition means;
• compression means for compressing the key information encoded and stored in the information recording medium;
• extraction means for extracting an identification information based on the key information compressed by the compression means and the error position and the error symbol value detected by the detection means, wherein the identification information represents whether the information recording medium is original or copied;
• determination means for determining whether a copy of the information recording medium is protected based on the identification information extracted by the extraction means;
• and
• copy protection means for protecting a copy of the information recording medium based on determination results of the determination means.

A computer program product for operating a computer, the computer program product comprising:

• a computer readable medium;
• digital data encoded and error-correction coded, the digital data including an identification information that is replaced with part of the digital data and recorded, wherein the identification information represents whether the computer readable medium is original or copied;
• and
• key information encoded for the digital data encoded and error-correction-coded,
• wherein each of the digital data and the encoded key information is recorded on the computer readable medium in executable form and loadable into the computer for execution by a processor.

A method for protecting information, comprising:

• decoding digital data, which is encoded and error-correction-coded, from an information recording medium in which key information encoded for the digital data is recorded;
• acquiring digital data encoded by error-correcting the decoded digital data;
• detecting an error position and an error symbol value of the acquired encoded digital data;
• detecting an identification information that is replaced with a part of the encoded and error-correction-coded digital data encoded and error-correction-coded based on the detected error position and error symbol value, wherein the identification information represents whether the information recording medium is original or copied;
• determining whether a copy of the information recording medium is protected based on the detected identification information;
• and
• protecting a copy of the information recording medium based on the determination.