Cache Control Module for Conditional Access Entitlement Processing
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Solution Overview
Problem
Existing software tamper-resistant conditional entitlement processing technologies are inefficient in terms of processor cycles, especially in devices with limited processing capabilities, due to the lack of consideration for the different life spans of subkeys, leading to unnecessary computations.
Innovation Solution
A receiver and method that utilize a cache memory and cache control module to intercept and search for cached results of transform functions and seeds, bypassing computations if the expected result is already available, thereby reducing the number of computations required to obtain a control word.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If software tamper-resistant conditional entitlement processing is performed using transform functions and seeds, then security and tamper resistance are improved, but computational efficiency deteriorates due to unnecessary computations
Solution Approach 1:
The patent applies preliminary action by pre-computing and caching control words for frequently used transform functions and seeds. The cache memory stores results of transform operations beforehand, so when the same transform function and seed combination is encountered during entitlement processing, the pre-computed control word can be retrieved immediately without performing the computation again. This resolves the contradiction by maintaining security through proper transform operations while improving computational efficiency through caching.
Solution Approach 2:
The patent uses copying by creating and storing copies of control words in a cache memory. Instead of repeatedly executing transform functions to generate control words, the system creates a copy of the control word result and stores it in cache memory for future reuse. This copying mechanism allows the system to maintain tamper-resistant processing while avoiding redundant computations, thus improving productivity without compromising security.
2Reliability
If transform functions are executed for every control word generation, then security is maintained, but processor cycles are wasted due to redundant computations
Solution Approach 1:
The patent applies copying by storing copies of previously computed control words in cache memory. When the same transform function and seed combination is needed, the system retrieves the copied control word from cache instead of re-executing the transform function. This maintains security by ensuring the same cryptographic operations are performed while avoiding redundant processor cycles through intelligent caching of results.
Solution Approach 2:
The patent uses preliminary action by pre-computing control words and storing them in cache memory before they are needed. The system anticipates that certain transform functions and seeds will be reused, so it performs the computation in advance and stores the result. This eliminates redundant processor cycles while maintaining the security properties of the transform operations.
3Productivity
If cache memory is introduced to store transform results, then computational efficiency is improved, but device complexity increases
Solution Approach 1:
The patent uses copying to store control word results in cache memory, which improves computational efficiency by avoiding redundant transform operations. The added complexity is minimal and focused specifically on the caching mechanism for control words, rather than fundamentally changing the overall receiver architecture. The cache memory and cache control module are integrated components that add functionality without significantly complicating the device.
Data Source
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AI summary
The invention provides a receiver, a smartcard and a conditional access system for securely obtaining a control word using an entitlement transform tree, wherein intermediate results are cached to improve computational efficiency.