Memory Protection Apparatus Metadata Update Handling
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Solution Overview
Problem
Data processing systems face challenges in ensuring memory protection against non-trusted external access, particularly in managing encryption metadata changes that affect encrypted data items stored in memory systems, while also optimizing access latency through system caches.
Innovation Solution
An apparatus with encryption circuitry and update control circuitry that encrypts and decrypts data items using metadata, managing changes by determining affected items, checking cache presence, and either retrieving or writing back encrypted data items based on update control data to maintain security and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If encryption metadata is updated to enhance security, then data protection reliability is improved, but cache consistency and access efficiency deteriorate due to required re-encryption operations
Solution Approach 1:
The system performs preliminary actions by detecting metadata changes before they take effect and proactively initiating re-encryption operations. The update control circuitry monitors for metadata changes and triggers re-encryption of affected cached data items before normal operations continue, preventing consistency issues and reducing overall access time penalties.
Solution Approach 2:
The system implements dynamic handling of cache operations based on metadata change status. When metadata changes are detected, the system dynamically switches between normal cache operation mode and re-encryption mode, adjusting the encryption state of cached data items in real-time to maintain both security and access efficiency.
2Stability of the object's composition
If all affected data items are re-encrypted when metadata changes, then encryption consistency is improved, but system productivity decreases due to additional processing overhead
Solution Approach 1:
The system applies local quality by selectively re-encrypting only the specific cache data items affected by metadata changes rather than re-encrypting all cached data. The update control circuitry identifies and processes only those data items whose encryption depends on the changed metadata, leaving unrelated cached data unchanged and accessible.
Solution Approach 2:
The system changes parameters by adjusting the encryption state of affected data items based on metadata change detection. When metadata changes occur, the system modifies the encryption parameters (keys, algorithms) for affected data items while maintaining original parameters for unaffected items, thereby preserving encryption consistency where needed while avoiding unnecessary processing elsewhere.
3Loss of energy
If cached data items are re-encrypted in place, then memory bandwidth usage is reduced, but device complexity increases due to additional control circuitry and coordination logic
Solution Approach 1:
The system introduces an intermediary component (the update control circuitry) that mediates between the encryption metadata and the cached data items. This intermediary detects metadata changes, identifies affected data items, and coordinates the re-encryption process, thereby managing the complexity centrally while enabling efficient in-place re-encryption operations without requiring complex distributed coordination.
Data Source
AI summary
Apparatuses and methods for memory protection are disclosed. A memory protection apparatus is interposed between a system cache and a memory system. The apparatus comprises encryption circuitry, which encrypts data item in dependence on encryption metadata and decrypts encrypted data items in dependence on the encryption metadata. In response to a change in a metadata item of the encryption metadata, when no cached copy of an affected data item is currently in the system cache, the affected data item is retrieved from the memory system, re-encrypted using the updated metadata item and returned to the memory system. When there is a cached copy, in dependence on update control data, the copy is retrieved from the system cache, encrypted using the updated metadata item and written out to the memory system.