Secure Debug Re-enablement in SoC Devices
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Solution Overview
Problem
Debug re-enablement in system-on-a-chip (SoC) devices poses security concerns for original equipment manufacturers (OEMs), as existing methods lack a secure and efficient way to re-enable disabled debug capabilities without compromising security.
Innovation Solution
A method involving a debug re-enable message with a token signed by a private key, using a unique identifier and a symmetric key, where the token is validated and compared to a locally generated comparison token, allowing re-enablement only if they match, ensuring secure reactivation of the debug capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If debug capability is disabled for security reasons, then security is improved, but the ability to debug devices for manufacturing defects is lost
Solution Approach 1:
The patent implements preliminary action by pre-configuring cryptographic key pairs (private and public keys) and symmetric keys in the SoC device during manufacturing. These cryptographic elements are prepared in advance to enable secure debug re-enablement later. The unique identifier is also pre-generated and stored, creating a foundation for future secure authentication without compromising initial security.
Solution Approach 2:
The patent uses cryptographic tokens as intermediaries to mediate between security requirements and debug capabilities. A debug re-enable token, signed with a private key and validated with a public key, serves as an intermediary credential. The symmetric key acts as another intermediary for generating comparison tokens. These intermediaries enable secure communication and authorization without exposing sensitive keys.
2Adaptability or versatility
If debug capability is re-enabled for defective devices, then manufacturing flexibility is improved, but security may be compromised
Solution Approach 1:
The patent applies local quality by making security credentials device-specific through the unique identifier. Each SoC device has its own unique identifier that is incorporated into the debug re-enable token and comparison token generation process. This ensures that debug re-enablement credentials are localized to specific devices, preventing unauthorized reuse across different devices while allowing legitimate debug access for defective units.
Solution Approach 2:
The patent performs preliminary cryptographic operations by pre-generating and storing the unique identifier, private key, and symmetric key in the SoC device during manufacturing. These preliminary actions establish a secure foundation that enables later debug re-enablement while maintaining security. The pre-configured cryptographic elements allow the device to independently verify debug authorization without requiring external security infrastructure.
3Reliability
If cryptographic validation is implemented for debug re-enablement, then security is improved, but system complexity increases
Solution Approach 1:
The patent segments the cryptographic validation process into distinct functional modules: a key management module for storing cryptographic elements, a token validation module for verifying the debug re-enable token using public key cryptography, and a comparison token generation module for creating local verification tokens using symmetric keys. This segmentation organizes the complex cryptographic operations into manageable, independent components that can be implemented and verified separately.
Data Source
AI summary
A disabled debug capability may be securely re-enabled in an integrated circuit such as a system-on-a-chip (SoC) device. In a method, the integrated circuit receives a debug re-enable message. The debug re-enable message includes a debug re-enable token signed by a private key. The debug re-enable token is based on a serial number of the integrated circuit and a first copy of a symmetric key. The debug re-enable token is validated using a public key corresponding to the private key. A comparison token is generated using the serial number of the integrated circuit and using a second copy of the symmetric key stored in a one-time-programmable (OTP) memory of the integrated circuit. The integrated circuit compares the debug re-enable token and the comparison token. The disabled debug capability is re-enabled in the integrated circuit if the debug re-enable token matches the comparison token.