| 摘要 |
Functionality is described for reducing the unauthorized reproduction of optical media, such as optical discs of various types. The functionality operates by adding a physical descriptor to an optical medium, forming reference descriptor information based on the descriptor (by reading the descriptor Lr times), producing authenticity information based on the reference descriptor information, and providing the authenticity information to a disc use site via various modes. At the disc use site, the functionality operates by reading the authenticity information and reading the descriptor Lv times (where Lv may not equal Lr). Based on the information that is read, the functionality performs cryptographic analysis and descriptor-based analysis to validate the optical medium. The descriptor can be formed on a closed loop of the optical medium. The functionality also includes provisions for reducing the possibility that unwanted correction is performed, which may interfere with analysis of the descriptor.
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