Optical Disc Copying Bypassing Signature Verification
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Solution Overview
Problem
Existing methods for copying optical discs are hindered by copy protection techniques that prevent accurate duplication, such as signature methods and data alteration, which deny access to the disc or degrade the copy quality.
Innovation Solution
A method and apparatus for copying optical discs by reading data from levels other than the user data level, such as the error corrected or encoded data level, and writing it back with generated error correction codes or additional codes, thereby bypassing copy protection mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If signature methods of copy protection are used, then access control is improved, but copying capability deteriorates
Solution Approach 1:
The patent segments the data reading process into multiple levels (user data level, error correction level, encoded level) and selectively reads from lower levels that bypass signature verification, allowing copying while maintaining access control for legitimate users
Solution Approach 2:
The patent uses error correction codes as an intermediary mechanism to bypass signature protection. By reading and copying data at the error correction level or encoded level, the system can create copies that include the necessary authentication data without triggering the signature verification block
2Manufacturing precision
If data alteration copy protection is applied, then copy quality is improved, but copying operation becomes blocked
Solution Approach 1:
Instead of preventing copying by altering user data, the patent inverts the approach by reading from lower data levels (error correction level or encoded level) where the alteration doesn't affect functionality, thereby enabling copying operations to proceed
Solution Approach 2:
The patent changes the reading parameter from user data level to error correction level or encoded level, which fundamentally alters which data is copied while maintaining copy quality and enabling the copying operation
3Device complexity
If error correction codes are discarded during reading, then copying is simplified, but authentication capability is lost
Solution Approach 1:
The patent performs preliminary reading of error correction codes at the error correction level or encoded level before the copying process, preserving authentication capability while maintaining a simplified copying process that doesn't require complex signature verification
Data Source
AI summary
To copy a copy protected DVD (32), and thereby subvert the copy prot-ection technique, a DVD drive (50) is controlled by a disc copying program (54) to access data at a level other than that at the user data level. For example, if it is the data frame (44) which is read, the DVD drive (50) is controlled to write a data frame (12) to a copy disc (52). During the copying process, the program (54) may be arranged to remove sector IDs and error detection codes from the read data frames (44) and to generate new sector IDs and appropriate ID error detection codes for the data frames (12) to be written to the copy disc (52). This circumvents any copy protection which has been incorporated in the identification data in a data frame of the original disc (52).