Memory Card Revocation List Version Verification
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Solution Overview
Problem
The risk of malicious devices accessing content due to the potential storage of old versions of revocation lists on memory cards, which can occur either accidentally or intentionally by manufacturers, leading to improper access and compromised security.
Innovation Solution
Implementing a system where the key issuing authority manages and distributes revocation lists, with a version verification mechanism that ensures only the latest valid revocation list is used, preventing the storage of older versions by prohibiting processing if an old version is detected, thus ensuring secure communication and device operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the card manufacturer stores the revocation list on the memory card, then the memory card can perform revocation checking, but the manufacturer may accidentally or intentionally store an old version of the revocation list, compromising security
Solution Approach 1:
The patent applies preliminary action by embedding the minimum version number in the public key certificate during the key issuance process. This allows the terminal device to verify the revocation list version before using it, preventing the use of outdated lists that could compromise security. The version check is performed in advance during authentication, ensuring that only current revocation lists are utilized.
2Object-affected harmful factors
If the terminal device verifies the revocation list version, then security is enhanced by preventing old version usage, but additional verification processing is required
Solution Approach 1:
The patent uses copying by embedding the minimum version number (a copy of the essential version information) directly in the public key certificate. This allows the terminal device to perform simple version comparison without needing to access or verify the entire revocation list structure, significantly reducing verification complexity while maintaining security.
3Adaptability or versatility
If the manufacturer intentionally stores an older version of the revocation list, then consumer appetite may be whetted, but malicious devices can access content that should be restricted
Solution Approach 1:
The patent implements feedback by requiring the terminal device to check the revocation list version against the minimum version number stored in the certificate. This feedback mechanism ensures that even if a manufacturer intentionally or accidentally loads an old revocation list, the system detects the version mismatch and prevents content access, thereby maintaining reliable access control.
Data Source
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AI summary
A memory card 30 includes a storage unit 302 storing key information and version information in association with the key information, the key information and the version information being issued by a key issuing authority, and the version information indicating a version of the latest revocation list that has been issued when the key information is generated; a revocation list receiving unit 304 that receives a revocation list having a version; a version verification unit 308 operable to compare the version of the revocation list received by the revocation list receiving unit 304 and the version information; and a revocation list writing unit 309. When the version of the revocation list is older than version information, processing by the revocation list writing unit 309 is prohibited.