Method for concealing hidden-object information, device and program for concealing hidden-object information, method for extracting hidden-object information, and device for extracting hidden-object information

1. A method for concealing hidden-object information using a first 2D barcode and a second 2D barcode,

the first 2D barcode containing first open information and first closed information,

the second 2D barcode containing second open information and second closed information,

the method, comprising:

generating the first 2D barcode,

the first closed information of the first 2D barcode containing an identifier,

the identifier being for identifying a protection mask pattern,

the protection mask pattern being for protection-encoding the second 2D barcode; and

generating a protection-encoded second 2D barcode by applying the protection mask pattern to at least a part of the second 2D barcode in accordance with an XOR operation,

the second closed information of the second 2D barcode containing the hidden-object information,

the open information being information that can be read-out with a standard decoder,

the closed information being information that cannot be read-out with the standard decoder but that can be extracted by an enhanced decoder.

2. A method for concealing hidden-object information according to claim 1 , wherein

the first 2D barcode is generated based on a first replaced data block,

the first replaced data block being obtained by replacing a part of a data block with a first closed data codeword,

the data block containing a first open data codeword and a first correction codeword,

the first closed data codeword containing the first closed information,

the first open data codeword containing the first open information,

the first correction codeword being capable of correcting an error of the first open data codeword.

3. A method for concealing hidden-object information according to claim 2 , wherein

the number of the first closed data codewords is not greater than the number of words that are corrected with the first correction codewords.

4. A method for concealing hidden-object information according to claim 2 , wherein

the first open data codeword contains first parity information,

the first parity information is parity information of information in which the first open information and the second open information are concatenated in a predetermined method.

5. A method for concealing hidden-object information according to claim 4 , wherein

the second 2D barcode is generated based on a second replaced data block,

the second replaced data block being obtained by replacing a part of a data block with a second closed data codeword,

the data block containing a second open data codeword and a second correction codeword,

the second closed data codeword containing the second closed information,

the second open data codeword containing the second open information,

the second correction codeword being capable of correcting an error of the second open data codeword.

6. A method for concealing hidden-object information according to claim 5 , wherein

the number of the second closed data codewords is not greater than the number of words that are corrected with the second correction codewords.

7. A method for concealing hidden-object information according to claim 5 , wherein

the second open data codeword contains second parity information, and

the second parity information is parity information of information in which the first open information and the second open information are concatenated in the predetermined method.

8. A method for concealing hidden-object information according to claim 1 , wherein

the method further comprises:

printing the first 2D barcode with a first ink; and

printing the protection-encoded second 2D barcode with a second ink,

the first ink and the second ink having different optical properties,

the printings are performed so that either one of the first 2D barcode and the protection-encoded second 2D barcode is superposed on the other 2D barcode.

9. A device for concealing hidden-object information using a first 2D barcode and a second 2D barcode,

the first 2D barcode containing first open information and first closed information,

the second 2D barcode containing second open information and second closed information,

the device, comprising:

generating the first 2D barcode,

the first closed information of the first 2D barcode containing an identifier,

the identifier being for identifying a protection mask pattern,

the protection mask pattern being for protection-encoding the second 2D barcode; and

generating a protection-encoded second 2D barcode by applying the protection mask pattern to at least a part of the second 2D barcode in accordance with an XOR operation,

the second closed information of the second 2D barcode containing the hidden-object information,

the open information being information that can be read-out with a standard decoder,

the closed information being information that cannot be read-out with the standard decoder but that can be extracted by an enhanced decoder.

10. A program causing a computer to perform a method for concealing hidden-object information using a first 2D barcode and a second 2D barcode,

the first 2D barcode containing first open information and first closed information,

the second 2D barcode containing second open information and second closed information,

the program causing a computer to perform the following processes:

generating the first 2D barcode,

the first closed information of the first 2D barcode containing an identifier,

the identifier being for identifying a protection mask pattern,

the protection mask pattern being for protection-encoding the second 2D barcode; and

generating a protection-encoded second 2D barcode by applying the protection mask pattern to at least a part of the second 2D barcode in accordance with an XOR operation,

the second closed information of the second 2D barcode containing the hidden-object information,

the open information being information that can be read-out with a standard decoder,

the closed information being information that cannot be read-out with the standard decoder but that can be extracted by an enhanced decoder.

11. A method for extracting hidden-object information for extracting the hidden-object information from a first 2D barcode and a protection-encoded second 2D barcode,

the first 2D barcode containing first open information and first closed information,

the first closed information containing an identifier,

the protection-encoded second 2D barcode having been protection-encoded by applying a protection mask pattern to a second 2D barcode in accordance with an XOR operation,

the second 2D barcode containing second open information and second closed information,

the second closed information containing hidden-object information,

the protection mask pattern being identified by the identifier,

the method comprising:

reading the first 2D barcode and the protection-encoded second 2D barcode;

identifying the protection mask pattern based on the identifier;

protection-decoding a protection-encoded codeword of the protection-encoded second 2D barcode in accordance with an XOR operation using data protection mask pattern; and

extracting the hidden-object information from the second 2D barcode that has been obtained by protection-decoding the protection-encoded codeword.

12. A method for extracting hidden-object information according to claim 11 , wherein

the first 2D barcode contains first parity information,

the second 2D barcode contains second parity information, and

under a condition that the first parity information coincides with the second parity information,

the hidden-object information contained in the second closed information is extracted from the second 2D barcode which has been obtained by protection-decoding the protection-encoded codeword.

13. A method for extracting hidden-object information according to claim 12 , wherein

both of the first parity information and the second parity information are parity information of information in which the first open information and the second open information are concatenated in a predetermined method.

14. A method for extracting hidden-object information according to claim 13 , wherein

the first 2D barcode is generated based on a first replaced data block,

the first replaced data block being obtained by replacing a part of a data block with a first closed data codeword,

the data block containing a first open data codeword and a first correction codeword,

the first closed data codeword containing the first closed information,

the first open data codeword containing the first open information,

the first correction codeword being capable of detecting and correcting an error of the first open data codeword.

15. A method for extracting hidden-object information according to claim 14 , wherein

concerning identifying the protection mask pattern that is applied to the second 2D barcode based on the first closed information contained in the first 2D barcode,

the identifying further comprises:

extracting the first closed data codeword from a predetermined position in the first replaced data block; and

identifying the protection mask pattern based on the the identifier contained in the first closed data codeword.

16. A method for extracting hidden-object information according to claim 14 , wherein

the number of the first closed data codewords is not greater than the number of words that are corrected with the first correction codewords.

17. A method for extracting hidden-object information according to claim 13 , wherein

the second 2D barcode is generated based on a second replaced data block,

the second replaced data block being obtained by replacing a part of a data block with a second closed data codeword,

the data block containing a second open data codeword and a second correction codeword,

the second closed data codeword containing the second closed information,

the second open data codeword containing the second open information,

the second correction codeword being capable of detecting and correcting an error of the second open data codeword.

18. A method for extracting hidden-object information according to claim 17 , wherein

concerning extracting the hidden-object information from the second 2D barcode that has been obtained by protection-decoding the protection-encoded codeword, the hidden-object information being contained in the second closed information,

the extracting further comprises:

extracting the second closed data codeword from a predetermined position in the second replaced data block; and

extracting the hidden-object information contained in the second closed data codeword.

19. A method for extracting hidden-object information according to claim 17 , wherein

the number of the second closed data codewords is not greater than the number of words that are corrected with the second correction codewords.

20. A method for extracting hidden-object information according to claim 11 , wherein

when the first 2D barcode and the protection-encoded second 2D barcode are printed so that either one of the first 2D barcode and the protection-encoded second 2D barcode is superposed on the other 2D barcode, and

when the first 2D barcode is printed with a first ink and the protection-encoded second 2D barcode is printed with a second ink,

the first ink and the second ink having different optical properties,

the first 2D barcode is read using a first light source that is for reading a subject printed with the first ink, and

the protection-encoded second 2D barcode is read using a second light source that is for reading a subject printed with the second ink.

21. A device for extracting the hidden-object information from a first 2D barcode and a protection-encoded second 2D barcode,

the first 2D barcode containing first open information and first closed information,

the first closed information containing an identifier,

the protection-encoded second 2D barcode having been protection-encoded by applying a protection mask pattern to a second 2D barcode in accordance with an XOR operation,

the second 2D barcode containing second open information and second closed information,

the second closed information containing hidden-object information,

the protection mask pattern data being identified by the identifier,

the device comprising:

reading the first 2D barcode and the protection-encoded second 2D barcode;

identifying the protection mask pattern based on the identifier;

protection-decoding a protection-encoded codeword of the protection-encoded second 2D barcode in accordance with an XOR operation using the protection mask pattern; and

extracting the hidden-object information from the second 2D barcode that has been obtained by protection-decoding the protection-encoded codeword.

22. A program causing a computer to perform a method for extracting the hidden-object information from a first 2D barcode and a protection-encoded second 2D barcode,

the first 2D barcode containing first open information and first closed information,

the first closed information containing an identifier,

the protection-encoded second 2D barcode having been protection-encoded by applying a protection mask pattern to a second 2D barcode in accordance with an XOR operation,

the second 2D barcode containing second open information and second closed information,

the second closed information containing hidden-object information,

the protection mask pattern being identified by the identifier,

the program causing a computer to perform the following processes:

reading the first 2D barcode and the protection-encoded second 2D barcode;

identifying the protection mask pattern based on the identifier;

protection-decoding a protection-encoded codeword of the protection-encoded second 2D barcode in accordance with an XOR operation using the protection mask pattern; and

extracting the hidden-object information from the second 2D barcode that has been obtained by protection-decoding the protection-encoded codeword.