Cryptography – Video cryptography – Copy protection or prevention
Reexamination Certificate
1998-11-19
2003-04-29
Barron, Gilberto (Department: 2134)
Cryptography
Video cryptography
Copy protection or prevention
C380S201000, C705S051000, C705S057000, C705S058000, C713S176000, C713S152000
Reexamination Certificate
active
06556679
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a copy-guard system for determining whether multimedia data recorded on a recording medium is original or copied and then preventing the data from being copied illegally when it is not original.
The present invention also relates to an information recording medium used in the above copy-guard system.
In a digital recording medium such as a DAT (Digital Audio Tape) and an MD (Mini Disc), a digital copy of the original can be made only once but a copy of the copied data (secondary copy) cannot be made again. This is called a CGMS (Copy Generation Management System) or an SCMS (Single Copy Management System). In these systems, a two-bit flag indicates whether data has been copied or not (data can be copied or not).
However, they have a problem in which data is likely to be altered and copied illegally during its transmission or a so-called pirated medium is likely to circulate.
Consequently, the conventional copy-guard system has such a problem as described above.
BRIEF SUMMARY OF THE INVENTION
The present invention has been developed in consideration of the above situation, and its object is to provide a copy-guard system for preventing an unauthorized copy based on identification information which represents whether the contents recorded on an information recording medium are the original or not and which is recorded in an error-correction code.
Another object of the present invention is to provide an information recording medium used in the above copy-guard system.
In order to attain the above objects, according to a first aspect of the present invention, there is provided 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;
identification information detection means for replacing the digital data encoded and error-correction-coded with 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 then recording the part of the digital data thereby to detect identification information representing 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.
According to a second aspect of the present invention, there is provided 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 replacing the digital data encoded and error-correction-coded by the inner code with 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 and then recording the part of the digital data thereby to detect identification information representing 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.
According to a third aspect of the present invention, there is provided 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 replacing the digital data encoded and error-correction-coded with part of the digital data encoded and error-correction-coded by 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, and then recording the part of the digital data thereby to detect identification information representing 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. According
According to a fourth aspect of the present invention, there is provided 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 replacing the digital data with part of the digital data and then recording the part of the digital data, thereby to detect identification information of the digital data decoded by the first decoding means, based on a pattern of identification information representing 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.
According to a fifth aspect of the present invention, there is provided 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 enc
Endoh Kenjiro
Endoh Naoki
Kato Takehisa
Katoh Taku
Yamada Hisashi
Barron Gilberto
Callahan Paul E.
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
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