Conditional Access Content Conversion Without Clear Text Exposure
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Solution Overview
Problem
Existing conditional access content conversion methods expose unencrypted content during the conversion process, making it vulnerable to unauthorized access and distribution.
Innovation Solution
A method that converts conditional access content from one encryption mode to another using a commutative combination of input data, ensuring that the content remains encrypted throughout the process by inverting the input data for decryption and re-encryption operations, using specific cryptographic parameters like keys and algorithms, and employing modes such as CBC, CTR, CFB, OFB, and XTS, without making the content available in clear form in the first receiver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conditional access content is decrypted in the first receiver and then re-encrypted for the second receiver, then format conversion is achieved, but the content becomes vulnerable to unauthorized access during the conversion process
Solution Approach 1:
The patent inverts the conventional decryption-encryption sequence by using encryption operations first with specific keys (CA key, then receiver key) and only performing decryption at the final destination. This inversion ensures content remains encrypted during transmission and conversion, eliminating the security vulnerability of having clear content in the first receiver while maintaining format conversion capability through cryptographic operations
Solution Approach 2:
The patent introduces cryptographic keys (CA key, receiver key, and intermediate keys) as mediators that enable format conversion without exposing content. These keys act as intermediaries that transform content between formats through encrypted operations, allowing the first receiver to convert content for the second receiver while keeping content protected throughout the process
2Reliability
If hardware protection is implemented to secure unencrypted content, then access difficulty increases, but determined users can still access and copy the content
Solution Approach 1:
The patent extracts the security vulnerability by removing the step that creates unencrypted content in the first receiver. By eliminating the decryption step at the first receiver and keeping content encrypted throughout the conversion process, the patent removes the target that hardware protection would need to defend against, making determined copying attempts unnecessary since clear content never exists in the system
Solution Approach 2:
The patent converts the potential harm of needing hardware protection into a benefit by using cryptographic encryption as the primary security mechanism. Instead of relying on hardware to protect unencrypted content, the system uses encryption to ensure content remains protected, turning the encryption requirement (which could be seen as a constraint) into the security solution itself
Data Source
AI summary
A method is disclosed for converting a conditional access content. This method includes receiving, by a cryptographic module of a first receiver, the content encrypted according to the first encryption mode; choosing a first entry data of the combination of the first encryption mode choosing a second entry data of the combination of the second encryption mode inverting the first and second input data in order to process the content received by the cryptographic module of the first receiver, this processing including a decryption operation according to the first encryption mode, by using the entry data corresponding to the second encryption mode, and to process the content obtained during the previous processing step, this processing including an encryption operation according to the second encryption mode, by using the entry data corresponding to the first encryption mode.