Method for copy protecting a record carrier, copy protected record carrier and means for detecting access control information
First Claim
1. A method for controlling access to a record carrier, comprising the steps of:
- creating an image file containing main information;
generating access control information for controlling the access to the main information;
producing a record carrier depending on the image file and the access control information, including the steps of;
creating a correctable bit sequence by applying formatting and error correcting rules to the image file;
modifying the correctable bit sequence according to the access control information with sufficient bit errors to provide uncorrectable errors which cannot be corrected by the error correcting rules and which constitute a predefined uncorrectable error pattern defined by uncorrectable error locations and error correctable locations; and
translating the modified bit sequence into a physical pattern of marks on the record carrier.
6 Assignments
0 Petitions
Accused Products
Abstract
A method for copy protecting a record carrier using a pattern of logical errors which cannot be corrected by the error correcting rules predefined for the record carrier. The pattern of logical errors represents access control information. The logical errors are generated during decoding the bit sequence read from the record carrier. Bit errors may be positioned in the bit sequence so as to counteract de-interleaving which is part of an error decoding process in a reading device and accumulate in error words which are uncorrectable. Also a method for detecting access control information and a retrieval arrangement, which detects the access control information by selecting at least one error location, but not all error locations on the record carrier, and verifying the presence of an error by reading the selected error location via the reading means.
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Citations
26 Claims
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1. A method for controlling access to a record carrier, comprising the steps of:
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creating an image file containing main information;
generating access control information for controlling the access to the main information;
producing a record carrier depending on the image file and the access control information, including the steps of;
creating a correctable bit sequence by applying formatting and error correcting rules to the image file;
modifying the correctable bit sequence according to the access control information with sufficient bit errors to provide uncorrectable errors which cannot be corrected by the error correcting rules and which constitute a predefined uncorrectable error pattern defined by uncorrectable error locations and error correctable locations; and
translating the modified bit sequence into a physical pattern of marks on the record carrier. - View Dependent Claims (2, 3, 4)
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5. A copy protected record carrier comprising:
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a substrate; and
a correctable bit sequence stored thereon representing information according to predefined formatting and error correcting rules, the information including main information and access control information for controlling the access to the main information, and in which the bit sequence includes means including sufficient bit errors for providing uncorrectable errors which cannot be corrected by the error correcting rules and which constitute a predefined uncorrectable error pattern representing at least part of the access control information, the uncorrectable error pattern defined by uncorrectable error locations and error correctable locations. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
storing a bit sequence representing information according to predefined formatting and error correcting rules on a record carrier, the information including main information and access control information for controlling the access to the main information, and in which the bit sequence includes sufficient bit errors to provide uncorrectable errors which cannot be corrected by the error correcting rules and which constitute a predefined uncorrectable error pattern representing at least part of the access control information, the uncorrectable error pattern defined by uncorrectable error locations and error correctable locations;
selecting at least one uncorrectable error location, but not all uncorrectable error locations, which uncorrectable error location(s) should have an uncorrectable error according to the predefined uncorrectable error pattern; and
verifying the presence of the uncorrectable error by reading the selected uncorrectable error location and detecting the uncorrectable error during error correction.
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16. The method of claim 15, in which the method further comprises the steps of:
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selecting at least one error correctable location, but not all error correctable locations, which error correctable location should not have an uncorrectable error according to the predefined uncorrectable error pattern; and
verifying the absence of an uncorrectable error by reading the selected error correctable location and attempting to detect an uncorrectable error.
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17. The method of claim 15, in which at least one error correctable location is selected which adjoins an uncorrectable error location.
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18. The method of claim 15, further comprising the a step of retrieving at least some access control information indicating the uncorrectable error pattern from the main information before selecting locations.
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19. The method of claim 15, in which, the record carrier is subdivided into addressable sectors, and the presence or absence of an uncorrectable error at a location is verified by reading the respective sector and detecting the uncorrectable error during error correction.
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20. The carrier of claim 5, in which the record carrier includes software for executing the method of selecting at least one uncorrectable error location, but not all uncorrectable error locations, which uncorrectable error location should have an uncorrectable error according to the predefined uncorrectable error pattern, and verifying the presence of the uncorrectable error by reading the selected uncorrectable error location and detecting the uncorrectable error during error correction.
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21. A retrieval arrangement for retrieving information from the copy protected record carrier of claim 5, the arrangement comprising:
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reading means for reading a copy protected record carrier, including a read unit for extracting a bit sequence stored on the record carrier and an error correcting unit for processing the bit sequence to retrieve the information that was copy protected; and
access control means for controlling the access to the information according to access control information detected by selecting at least one uncorrectable error location, but not all uncorrectable error locations, which at least one uncorrectable error location should have an uncorrectable error according to the uncorrectable error pattern, and by verifying the presence of an uncorrectable error by reading the selected uncorrectable error location via the reading means and detecting an uncorrectable error during error correction.
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22. The retrieval arrangement of claim 21, in which, the record carrier is subdivided into addressable sectors, and the reading means includes a control unit for controlling the reading of a sector and generating an error message when an uncorrectable error is detected.
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23. A recorder for producing the copy protected record carrier of claim 5, comprising:
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means for providing an image file containing main information;
means for generating access control information for controlling access to the main information;
means for producing a record carrier depending on the image file and the access control information, including the steps of;
creating a correctable bit sequence by applying the formatting and error correcting rules to the image file;
modifying the correctable bit sequence according to the access control information to constitute uncorrectable errors which cannot be corrected by the error correcting rules and which constitute a predefined uncorrectable error pattern defined by uncorrectable error locations and error correctable locations; and
translating the modified bit sequence into a physical pattern of marks on the record carrier.
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24. A player for detecting access control information on a record carrier of claim 5 to access other information on the record carrier, comprising:
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means for selecting at least one uncorrectable error location, but not all uncorrectable error locations on a record carrier, which uncorrectable error location should have an uncorrectable error according to a predefined uncorrectable error pattern; and
means for verifying the presence of an uncorrectable error by reading the selected uncorrectable error location and detecting an error that can not be corrected during error correction.
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25. A system for programming to produce a recorder for producing the copy protected record carrier of claim 5, comprising:
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means for providing programmed apparatus for generating access control information for controlling the access to an image file of main information;
means for providing programmed apparatus for producing a record carrier depending on the image file and the access control information, including;
means for providing programmed apparatus for creating a bit sequence by applying formatting and error correcting rules to the image file;
means for providing programmed apparatus for modifying the bit sequence according to the access control information to constitute uncorrectable errors which cannot be corrected by the error correcting rules and which constitute a predefined uncorrectable error pattern defined by uncorrectable error locations and error correctable locations;
means for providing programmed apparatus for translating the modified bit sequence into a physical pattern of marks on the record carrier.
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26. A system for programming to produce a player for playing the record carrier of claim 5, comprising:
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means for providing programmed apparatus for selecting at least one uncorrectable error location, but not all uncorrectable error locations, which uncorrectable error location should have an uncorrectable error according to a predefined uncorrectable error pattern; and
means for providing programmed apparatus for verifying the presence of the uncorrectable error by reading the selected uncorrectable error location.
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Specification