AV Data Transmission Cipher Algorithm Switching
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Solution Overview
Problem
Existing AV data transmission systems, such as those using the DTCP specification, fail to effectively transmit new usage control information, leading to unauthorized analog output in devices that do not support new usage control settings, causing users to incorrectly diagnose apparatus failures or transmission errors.
Innovation Solution
An AV data transmission apparatus and system that encrypts AV data using a first cipher scheme, prohibiting use in unsupported devices, and switches cipher type information to a second scheme that prevents decryption in non-compliant devices, allowing users to recognize the encryption as the cause of incompatibility rather than a failure or error.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If new usage control information is transmitted using existing cipher schemes, then compatibility with legacy devices is maintained, but unauthorized use and analog output in unsupported devices cannot be prevented
Solution Approach 1:
The patent introduces a new parameter (Cipher_Algorithm) to select between different cipher schemes. By changing the cipher scheme parameter from conventional (DES) to extended (AES), the system can enforce new usage control information while maintaining backward compatibility through parameter negotiation during authentication
Solution Approach 2:
The patent uses Cipher_Algorithm information as an intermediary to bridge legacy and extended systems. This intermediary parameter allows legacy devices to identify when they cannot support the requested cipher scheme, enabling graceful degradation while still transmitting the usage control prohibition to unsupported devices
2Ease of operation
If conventional encryption methods are used, then legacy devices can decrypt and use AV data, but usage control information cannot be effectively enforced
Solution Approach 1:
The patent makes the cipher scheme dynamic rather than fixed. The AV data transmission apparatus can select between conventional and extended cipher schemes based on the capabilities of the receiving device, as determined during authentication. This dynamic selection allows the system to adapt its security level to match device capabilities
Solution Approach 2:
The patent performs preliminary authentication and cipher scheme selection before AV data transmission. By determining device capabilities and selecting the appropriate cipher scheme in advance, the system prevents unauthorized use before data transmission begins, rather than attempting to enforce controls after decryption
3Reliability
If cipher scheme is switched to prevent unauthorized use, then copyright protection is strengthened, but users cannot distinguish encryption from apparatus failure
Solution Approach 1:
The patent implements feedback through the Cipher_Algorithm parameter transmission. When a device cannot decrypt data, it receives feedback in the form of Cipher_Algorithm information indicating which cipher scheme was used. This feedback allows the device to understand that incompatibility (not failure) is the cause and display an appropriate message to the user
Data Source
AI summary
An AV data transmission apparatus includes an encryption unit which encrypts AV data, an AV data transmission unit which transmits the encrypted AV data, a cipher-type-information switching unit which switches cipher type information indicating a cipher scheme used for the AV data, to other cipher type information, and a cipher-type-information transmission unit which transmits cipher type information. When transmitting AV data which is prohibited from being used in a reception apparatus that does not support new usage control information, the AV data transmission apparatus assigns different cipher type information, which is used to notify the reception apparatus, so that even the reception apparatus which cannot recognize the new usage control information can recognize its inability to perform decryption is due to new encryption performed by the AV data transmission apparatus.