Debug Authentication Interface for Secure Processor Access

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Solution Overview

Problem

Existing electronic devices face challenges in securely allowing access to memory, processing units, and peripherals for debugging purposes while maintaining data security, especially for sensitive information like encryption keys and software codes.

Innovation Solution

An electronic device with a debug port, authentication interface circuit, and access ports that can be controlled between open and closed states, along with registers for managing communication and authentication, ensures secure access for debugging by external devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If access ports are opened to allow debugging access to memory and processing units, then debugging capability is improved, but data security deteriorates

Engineering Contradiction:

Improvedebugging accessVSAvoiddata security

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

An authentication interface circuit is introduced as an intermediary between the debug port and the processing units/memory. This intermediary controls access by authenticating external devices before allowing debug access, thus enabling debugging functionality while maintaining data security through selective authorization.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The access ports are designed to be dynamically controllable, switching between open and closed states based on authentication results. The authentication interface circuit can open access ports for authorized debuggers while keeping them closed for unauthorized access attempts, providing dynamic security control.

Inventive Principle:

Principle #15Dynamics

2Object-affected harmful factors

If access ports are closed to protect sensitive data, then data security is improved, but debugging capability deteriorates

Engineering Contradiction:

Improvedata securityVSAvoiddebugging access

Core Design Contradiction:

Object-affected harmful factorsVSEase of operation

Solution Approach 1:

Authentication is performed in advance before opening access ports. The authentication interface circuit verifies the credentials of external devices beforehand, and only after successful authentication does it open the access ports. This preliminary authentication ensures that debugging access is granted only to authorized devices.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The authentication interface circuit serves as a mediator that sits between the closed access ports and external debuggers. It manages the transition from closed to open state based on authentication outcomes, enabling secure controlled access without permanently opening ports.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If multiple access ports are provided for different processing units, then debugging versatility is improved, but device complexity increases

Engineering Contradiction:

Improvedebugging coverageVSAvoidinterface structure

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The authentication interface circuit is designed with universal functionality to handle multiple access ports and different processing units through a single unified interface. This multi-functional design provides versatile debugging coverage across different processing units while avoiding the need for separate authentication mechanisms for each port, thus managing complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Object-affected harmful factors

If authentication mechanisms are added to control access ports, then data security is improved, but device complexity increases

Engineering Contradiction:

Improvedata securityVSAvoidcircuit structure

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The authentication interface circuit combines multiple functions including authentication verification, access port control, and status monitoring into a single integrated circuit. This merging of functions provides enhanced security capabilities while avoiding the complexity increase that would result from separate discrete components for each function.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS12547698B2Host-device interface for debug authentication

Publication Date: 2026.02.10 STMICROELECTRONICS INT NV

AI summary

An electronic device includes a debug port providing a communications interface for debugging purposes, a plurality of processing unit access ports, an authentication interface circuit configured to authenticate the external device, and a further access port coupled between the debug port and the authentication interface circuit. The further access port is configured to be in an open state in which communications are relayed between the debug port and the authentication interface circuit. The authentication interface circuit has registers including a status register capable of being read by the external device via the debug port and the further access port, the status register being configured to store an indication of the open or closed state of each of the processing unit access ports.