Secure Chip Idle State Hash Value Management
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Solution Overview
Problem
Existing secure chip technologies face challenges in detecting tampering of application software upon returning from an idle state, as hash values stored in non-volatile memory do not match those in volatile memory, leading to inconsistent tampering detection results.
Innovation Solution
An information processing apparatus with a secure chip that saves hash values from volatile memory to non-volatile memory before transitioning to an idle state and restores them upon return, ensuring consistent tampering detection by initializing volatile memory to prevent false positives and negatives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hash values are saved in non-volatile memory before transitioning to idle state, then tampering detection availability is improved upon return from idle state, but inconsistency between non-volatile memory and volatile memory hash values occurs when application software is executed
Solution Approach 1:
The patent applies preliminary action by saving hash values to non-volatile memory before transitioning to idle state, ensuring that hash values are available for tampering detection upon return. This pre-saving mechanism guarantees detection availability without affecting subsequent software execution.
Solution Approach 2:
The patent introduces a flag as an intermediary element to manage the state between volatile and non-volatile memory. The flag indicates whether hash values have been saved, allowing the system to distinguish between different operational states and prevent incorrect tampering detection results without requiring direct consistency between memory contents.
2Measurement precision
If non-volatile memory is initialized to prevent inconsistency, then false positive tampering detection is reduced, but false negative detection occurs when hash values of other software are not registered
Solution Approach 1:
The patent implements feedback through a flag that tracks whether hash values have been saved to non-volatile memory. This feedback mechanism allows the system to conditionally initialize non-volatile memory only when appropriate, preventing both false positives (by avoiding unnecessary initialization) and false negatives (by ensuring initialization occurs when hash values are actually registered).
Solution Approach 2:
The patent changes the state parameter of the flag to control the initialization behavior of non-volatile memory. By transitioning the flag state based on whether hash values are registered, the system dynamically adjusts memory initialization behavior to match the actual operational context, ensuring accurate and complete tampering detection.
3Use of energy by moving object
If power supply to TPM is stopped during idle state, then energy consumption is reduced, but hash values in volatile memory disappear causing tampering detection to become unavailable
Solution Approach 1:
The patent applies copying by duplicating hash values from volatile memory to non-volatile memory before entering idle state. This creates a persistent copy that survives the power shutdown, enabling tampering detection to resume immediately upon power restoration without requiring continuous power to maintain hash values.
Solution Approach 2:
The patent performs the action of saving hash values to non-volatile memory in advance before transitioning to idle state. This preliminary saving ensures that when power is stopped and volatile memory is cleared, the hash values are already preserved and can be restored without delay, maintaining both energy efficiency and detection availability.
Data Source
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AI summary
An information processing apparatus holding a secure chip (112) includes determination means that determines whether the information processing apparatus is returning from an idle state; detection means that, if the determination means determines that the information processing apparatus is returning from the idle state, detects initialization of the secure chip before starting application software; and control means that, if the detection means detects the initialization of the secure chip, controls an operation of the information processing apparatus so that a hash value of the application software is not registered in the secure chip that is initialized.