Semiconductor Device Lifecycle Phase Transition for Key Invalidation
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Solution Overview
Problem
Existing methods for managing encryption keys in vehicle-mounted electronic devices fail to ensure secure invalidation during the discard phase, leaving private user data vulnerable to malicious access.
Innovation Solution
A method where a processor transitions the semiconductor device from the operation phase to the discard phase, requesting a security module to invalidate secret information stored in OTP memory, thereby preventing further system operations and ensuring the encryption key cannot be exploited.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the encryption key is stored in OTP memory for repeated use in the operation phase, then the key can be used multiple times for decrypting and protecting data, but the key becomes vulnerable to malicious access and data restoration in the discard phase
Solution Approach 1:
The system dynamically transitions the encryption key between different states based on the vehicle's lifecycle phase. During the operation phase, the key is accessible for normal cryptographic operations. When transitioning to the discard phase, the key is automatically invalidated and rendered inaccessible, preventing any further use or restoration by malicious actors.
Solution Approach 2:
The system changes the accessibility parameter of the encryption key based on the lifecycle phase. In the operation phase, the key has full accessibility for cryptographic operations. In the discard phase, the key's accessibility parameter is changed to restricted/invalidated, ensuring it can no longer be used for any cryptographic operations.
2Ease of operation
If the system allows normal operation during the operation phase, then cryptographic operations can be performed, but the encryption key may be exploited by malicious third parties
Solution Approach 1:
The system performs preliminary validation of the lifecycle phase before allowing any cryptographic operations. By checking whether the current phase is still the operation phase, the system prevents malicious access attempts before they can succeed, ensuring that no cryptographic operations are permitted in the discard phase.
Solution Approach 2:
The security module acts as an intermediary between the processor and the encryption key. It mediates access to the key by validating the lifecycle phase and controlling whether the key is made accessible for cryptographic operations or invalidated, thus preventing direct malicious access while maintaining normal operations during the operation phase.
3Reliability
If the encryption key is invalidated in the discard phase, then user private data is protected from restoration, but the system cannot be activated or operated
Solution Approach 1:
The system segments the operational lifecycle into distinct phases (operation phase and discard phase) with different security requirements. During the operation phase, the system is fully operational. In the discard phase, the key is invalidated to protect data, and the system is designed to stop all operations, preventing both data restoration and system activation.
4Productivity
If the key management system continues to operate after the discard phase, then system functionality is maintained, but security assurance is compromised
Solution Approach 1:
Instead of maintaining system functionality while trying to protect keys, the system inverts the approach: when the discard phase is detected, it immediately stops all system operations and invalidates the key. This inversion prioritizes security assurance over system continuity, ensuring that no cryptographic operations can be performed after the discard phase begins.
Data Source
AI summary
This invention provides a method of managing secret information that ensures that key information in the discard phase can be invalidated and that the system cannot be started. In method of managing secret information in a semiconductor device, the semiconductor device has an OTP (One Time Programmable) module, a security module and a processor. The OTP module further has an OTP memory for storing a secret information and a lifecycle flag for defining an operation phase and a discard phase, a sequencer for reading information stored in the OTP memory and a register for storing the information read by the sequencer. The security module performs a process by the secret information. The processor requests the process to the security module when changing the operation phase to the discard phase and sends a request to the security module to invalidate the secret information.