Hardware Key Control for Debug Interface Security
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Solution Overview
Problem
Existing electronic equipment protection methods, such as mechanical locks, do not effectively prevent reverse engineering through externally accessible interfaces like JTAG, as these interfaces can be exploited to access and modify internal components.
Innovation Solution
A system that incorporates a hardware key interface and monitor to control access to debug functionality, ensuring communication over debug interfaces is only permitted when an authorized hardware key is present and coupled, utilizing encryption and authentication protocols to secure communications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical lock is used to prevent physical access to the case, then physical security is improved, but access to externally accessible interfaces like JTAG remains unsecured
Solution Approach 1:
The patent segments the security protection into two independent layers: physical security (mechanical lock) and interface security (hardware key control). The hardware key interface operates independently from the mechanical lock, providing separate control over debug interface access. This allows the mechanical lock to protect physical access while the hardware key controls logical access through externally accessible interfaces.
Solution Approach 2:
The patent introduces a hardware key as an intermediary between the external debug device and the internal debug functionality. The hardware key interface acts as a mediator that authenticates and authorizes communication attempts. Without the authorized hardware key, the debug interface cannot establish communication with the internal electronics, thus preventing reverse engineering while maintaining physical accessibility.
2Object-affected harmful factors
If a hardware key interface is added to control debug interface access, then security against reverse engineering is improved, but device complexity increases
Solution Approach 1:
The hardware key interface is designed to serve multiple functions: it authenticates authorized devices, controls access to the debug interface, and can prevent reverse engineering. By integrating this multi-functional control mechanism into the existing debug interface architecture, the patent avoids adding separate independent security systems, thereby limiting the increase in device complexity.
Solution Approach 2:
The patent replaces the purely mechanical security approach with an electronic/hardware-based key control system. Instead of relying solely on physical access controls, the system uses hardware keys and interface control logic to secure the debug functionality. This substitution allows for more flexible and scalable security without requiring complex mechanical locking mechanisms for every access point.
3Reliability
If hardware key control is implemented to prevent unauthorized access, then protection of internal components is improved, but ease of operation for authorized users may be reduced
Solution Approach 1:
The hardware key must be coupled to the hardware key interface before any debug operations can occur. This preliminary authentication action establishes authorized access before the user attempts to use the debug interface. Once the hardware key is properly coupled, subsequent debug operations proceed normally without repeated authentication, maintaining ease of operation for authorized users while ensuring protection for unauthorized access attempts.
Data Source
AI summary
In one embodiment, a system comprises debug functionality, a debug interface communicatively coupled to the debug functionality, and a hardware key interface. Communication with the debug functionality over the debug interface is not permitted if an authorized hardware key is not communicatively coupled to the hardware key interface.