Dummy Write Operations for Non-Volatile Memory Security
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Solution Overview
Problem
Existing security mechanisms for smart cards, such as incrementing and decrementing retry counters, stress non-volatile memory and impact its endurance and data retention, making them vulnerable to power analysis attacks.
Innovation Solution
Implementing a dummy write operation that mimics an actual write operation by starting a charge pump and selecting a data line, fooling attackers into believing a retry count was updated, even if no data is written to memory, thus preserving physical endurance and obscuring power traces for both positive and negative comparisons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the retry counter is written to non-volatile memory after each comparison, then the security against power analysis attacks is improved, but the endurance and data retention of the non-volatile memory are degraded
Solution Approach 1:
The system performs a preliminary dummy write operation to the non-volatile memory before the actual write operation. This dummy write mimics the power consumption pattern of a real write operation, causing the attacker to believe that the retry counter has been updated, while the actual write only occurs when necessary, thus reducing the total number of writes to the non-volatile memory and extending its endurance
Solution Approach 2:
The system creates a copy of the write operation sequence by implementing a dummy write that replicates the power consumption characteristics of a real write without actually writing data to the non-volatile memory. This copy allows the system to deceive power analysis attackers while preserving the integrity and longevity of the non-volatile memory
2Reliability
If the retry counter is incremented before comparison, then the security against power analysis attacks is improved, but the complexity of the security mechanism is increased
Solution Approach 1:
The system implements a dummy write operation that copies the power consumption pattern of a real write operation without actually writing data. This allows the system to maintain simple increment-before-comparison logic while still providing security, as the dummy write mimics the power trace of a real write, preventing power analysis attacks without adding complex conditional logic
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The dummy write operation effectively prevents attackers from determining the result of comparisons through power analysis, enhancing security without degrading non-volatile memory performance.
Implementation Method 1
starting a charge pump, selecting a correct data line in the memory array
Data Source
AI summary
A dummy write operation is disclosed that mimics an actual write operation to a memory array. In some implementations, a dummy write operation mimics an actual write operation by starting a charge pump, selecting a correct data line in the memory array, and by following the sequencing of an actual write operation. By mimicking an actual write operation, an attacker cannot use power analysis to distinguish between dummy and actual write operations. For example, PIN comparison operations would present the same or substantially the same power trace for both positive and negative comparisons, making it difficult for an attacker to determine if a retry count was written to NVM.