Temporal Integrity Protection for Non-Secure Memory Data
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Solution Overview
Problem
Existing methods for temporal integrity protection of data in non-secure memory require frequent access to secure memory, leading to performance degradation and insufficient capacity for storing all necessary counters, which hampers efficient data access and security.
Innovation Solution
A method that involves reading and checking counters in non-secure memory, storing copies in secure memory, and using counter indicators and fingerprints to ensure data integrity with minimized secure memory usage, allowing for efficient incrementation and verification of counter values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If temporal integrity protection is implemented by storing all counters in secure memory, then data integrity is ensured, but secure memory capacity is insufficient and access performance degrades
Solution Approach 1:
The patent segments the counter storage into two parts: frequently accessed counters are stored in secure memory while less frequently accessed counters remain in non-secure memory. This segmentation allows the system to maintain temporal integrity protection for critical counters without requiring all counters to be stored in limited secure memory capacity.
Solution Approach 2:
The patent introduces a hash function as an intermediary mechanism to verify counter integrity. Instead of directly storing and comparing all counter values in secure memory, the system stores hash values of counters and uses these as intermediaries to verify temporal integrity, reducing the storage requirements in secure memory.
2Reliability
If hashes are recalculated and verified on each memory access, then temporal integrity is protected, but system performance slows down due to repeated secure memory accesses
Solution Approach 1:
The patent performs preliminary actions by pre-calculating and storing hash values of counters in secure memory before actual data access occurs. When data is accessed, the system retrieves and compares pre-stored hash values rather than recalculating hashes on-the-spot, significantly reducing the computational overhead during critical data access operations.
Solution Approach 2:
The patent creates copies of counter hash values and stores them in secure memory for verification purposes. This copying mechanism allows the system to verify temporal integrity by comparing current counter hashes against stored copies without requiring repeated access to the original counter storage locations, improving access performance.
3Quantity of substance
If all counter data is stored in non-secure memory, then storage capacity is sufficient, but temporal integrity protection cannot be ensured
Solution Approach 1:
The patent extracts critical integrity verification data (counter hash values) from non-secure memory and places them in secure memory. This extraction allows the majority of counter data to remain in capacity-rich non-secure memory while the essential verification elements reside in secure memory, ensuring temporal integrity protection without sacrificing storage capacity.
Data Source
AI summary
The invention relates to a method for accessing information stored securely in data blocks (Wl) of an unsecured memory (214), each data block (Wl) being associated with a counter (GCk) recorded in the unsecured memory (214), said counter (GCk) being adapted to be incremented each time said data block (Wl) is written. The method comprises the following steps: - reading, in the unsecured memory (214), a recorded counter (GCk) associated with a data block (Wl) to which it is accessed, - checking the integrity of the counter (GCk), and - storing, in a secure memory (222), a stored counter (GC'k) consisting of a copy of said recorded counter (GCk).