Chip Debug Authentication via Secure Boot and Intermediary Verification
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Solution Overview
Problem
Chips with limited non-volatile memory capacity face challenges in securely managing debugging functions during development, as they need to prevent unauthorized access by external debug tools while allowing authenticated users to access valuable assets.
Innovation Solution
A chip with a secure boot firmware, public key, and debugging function control component that verifies signed programs and users through a debug user authentication algorithm, ensuring only valid users can access and control debugging functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the chip stores debug firmware programs in external storage devices, then the storage capacity is sufficient for complicated software programs, but the security risk increases due to unauthorized access by external debug tools
Solution Approach 1:
The patent introduces an authentication mechanism as an intermediary between the external debug tool and the chip's debugging functions. The debug firmware program stored externally must be authenticated by the chip before allowing access to debugging functions, thus mediating the security risk while maintaining external storage capability
Solution Approach 2:
The patent implements preliminary authentication of the debug firmware program before granting access to debugging functions. The chip verifies the authenticity and authority of the external debug firmware program in advance, preventing unauthorized access before it can occur
2Ease of operation
If the chip equips debugging functions to allow external debug tools to access chip resources, then the ease of operation for developers improves, but the security risk increases due to potential access to valuable assets
Solution Approach 1:
The authentication mechanism serves as an intermediary layer between the external debug tool and the chip's valuable assets. Even though debugging functions are accessible, the intermediary authentication process ensures that only authorized debug firmware programs can access specific chip resources, thus maintaining ease of operation for legitimate users while protecting against security risks
3Ease of manufacture
If the chip uses a one-time program non-volatile memory unit for storing setting values, then the cost is reduced, but the flexibility decreases due to inability to update debug firmware
Solution Approach 1:
The patent segments the memory storage into two parts: a small capacity one-time program non-volatile memory unit for storing essential setting values and authentication data, and external storage devices for storing the actual debug firmware programs. This segmentation allows the chip to maintain low manufacturing costs while enabling firmware updates through external storage
Solution Approach 2:
The authentication mechanism acts as an intermediary that enables the system to use external storage for firmware storage without compromising security. The small internal memory stores authentication credentials, while external storage holds the firmware, with the authentication process mediating between them
Data Source
AI summary
A chip capable of authenticating an off-chip debug firmware program and a debug user account is illustrated. The chip runs the secure boot firmware and executes the secure boot process to verify whether the debug firmware program in a signed program loaded from an external storage device may be executed. After the signed program is successfully verified, the chip runs the debug firmware program to execute a debug user authentication algorithm in the signed program, thereby starting a debug user authentication process. After verifying the debug user account of the external debugging tool connected to the chip is a valid debug user account, the debugging tool is allowed to use the debugging function in the chip according to the authority of the debug user.