Irreversible Testing Mode Switch for Secure Processing Device Analysis
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Solution Overview
Problem
Processing devices often fail and are returned for testing, requiring effective methods to identify failure causes and prevent reuse after testing, as existing techniques lack a reliable mechanism to irreversibly disable normal operation for testing purposes.
Innovation Solution
A processing device is irreversibly placed into a testing mode by activating a non-reversible switch, allowing only specially signed software to execute, with functionality limited in secure diagnostic mode and further restricted in analysis mode, ensuring the device cannot revert to normal operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If processing devices are returned for testing after failure, then failure analysis can be performed, but the devices may be reused after testing which compromises system security
Solution Approach 1:
The patent applies preliminary action by activating the non-reversible switch to testing mode before the actual failure analysis is completed. This ensures that once the device enters testing mode, it cannot revert to normal operation, preventing any possibility of reuse after testing. The irreversible state is established in advance, eliminating the security risk of post-testing device reuse while maintaining the ability to perform comprehensive failure analysis.
2Object-affected harmful factors
If normal operation is disabled during testing, then device security is improved, but testing functionality is restricted
Solution Approach 1:
The patent segments the device operation into distinct modes: normal operation mode and testing mode. The non-reversible switch creates a clear division between these states. In testing mode, the device provides comprehensive testing functionality including failure analysis capabilities, while normal operation is completely disabled. This segmentation ensures that when in testing mode, the device offers full testing versatility without the security risk of normal operation, and the two functionalities do not overlap or conflict.
3Object-affected harmful factors
If a non-reversible switch is activated, then device reuse is prevented, but the activation process must be irreversible
Solution Approach 1:
The patent replaces a purely mechanical switch with an electrical/electronic implementation. The non-reversible switch is activated by receiving an activation signal that triggers an irreversible electrical state change, such as blowing a fuse or triggering a one-time programmable memory element. This substitution makes the irreversibility more reliable and easier to manufacture compared to mechanical solutions, as electrical components can be integrated directly into the device circuitry and controlled through software or hardware signals without requiring physical manipulation.
Data Source
AI summary
A technique for operating a processing device is disclosed. The method includes irreversibly activating a testing mode switch of the processing device; in response to the activating, entering a testing mode in which normal operation of the processing device is disabled; receiving software for the processing device in the testing mode; based on whether the software is verified as testing mode-signed software, executing or not executing the software.