Microcontroller Security State Transition for Secure Reuse

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Solution Overview

Problem

The existing methods for reusing secure microcontrollers, such as those used in battery management, require returning them to the factory for deletion of secret information and disabling security features, which is cumbersome and exposes the system to unauthorized access risks.

Innovation Solution

A method and microcontroller configuration that allows local deletion of secret information and disabling of security features via atomic operations, enabling transition to a secondary mode for reuse without factory intervention, using a state indicator and non-volatile memory to manage security configurations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the microcontroller is returned to the factory line for deletion of secret information and disabling of security features, then the integrity of manufacturer secrets is preserved, but the process complexity and time required increase significantly

Engineering Contradiction:

Improveintegrity of manufacturer secretsVSAvoidprocess complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The microcontroller performs self-erasure of secret information and self-transition to secondary mode through locally stored deletion instructions and state indicators, eliminating the need for factory intervention while maintaining security integrity

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

Deletion instructions and security configurations are pre-stored in non-volatile memory during manufacturing, enabling the microcontroller to autonomously execute erasure operations and transition to secondary mode without requiring factory line intervention

Inventive Principle:

Principle #10Preliminary action

2Reliability

If the microcontroller operates in security state with all security features enabled, then protection against unauthorized access is maximized, but the adaptability for reuse in different applications is reduced

Engineering Contradiction:

Improveprotection against unauthorized accessVSAvoidadaptability for reuse

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The microcontroller dynamically transitions between primary mode (full security enabled) and secondary mode (security features disabled) based on operational requirements, allowing it to adapt from secure operation to reusable repurposing without manual intervention

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The security configuration parameters are changed by transitioning to secondary mode, which modifies the operational state of security features from enabled to disabled, enabling reuse while maintaining security during operation

Inventive Principle:

Principle #35Parameter changes

3Loss of time

If local deletion of secret information is implemented, then the time required for reuse is reduced, but the risk of unauthorized access during the deletion process increases

Engineering Contradiction:

Improvetime required for reuseVSAvoidrisk of unauthorized access

Core Design Contradiction:

Loss of timeVSObject-affected harmful factors

Solution Approach 1:

Deletion instructions are pre-stored in non-volatile memory in a secure manner, enabling autonomous execution without requiring the microcontroller to be in a vulnerable state during the deletion process

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

A state indicator and non-volatile memory act as intermediaries that store deletion instructions and transition states, mediating between the secure primary mode and the reusable secondary mode without exposing the system to unauthorized access during transition

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS20260003517A1Method for configuring a microcontroller and corresponding microcontroller

Publication Date: 2026.01.01 STMICROELECTRONICS INT NV

AI summary

A microcontroller includes a non-volatile memory storing secret data including a first set of security configurations, a second set of security configurations, and a state of the microcontroller being a first value indicating a first operation mode, a second value indicating a transition from the first operation mode to a second operation mode, or a third value indicating the second operation mode. If the state of the microcontroller is equal to the first value, it is operated in the first operation mode using the first set of security configurations. If the state of the microcontroller is equal to the second value, the secret data is erased and the microcontroller is operated in the second operation mode using the second set of security configurations. If the state of the microcontroller is equal to the third value, it is operated in the second operation mode using the second set of security configurations.