Microcontroller Hardware Authentication for Cryptographic Security

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Solution Overview

Problem

Current security measures in microcontrollers, which rely on software to determine the legitimacy of programs, are insufficient due to vulnerabilities in software that can lead to falsification and information leakage.

Innovation Solution

Incorporating a cryptographic processing circuit that decrypts and verifies installation information for programs, ensuring only authorized programs can use the cryptographic processing unit, thereby enhancing security by using hardware-based authentication.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If software-based security measures are used to determine program legitimacy, then the system is easier to implement and maintain, but security reliability is insufficient due to software vulnerabilities

Engineering Contradiction:

Improvesecurity reliabilityVSAvoidsystem complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces software-based security verification with hardware-based verification. The verification unit is implemented as a hardware circuit that directly checks whether the current program counter value matches the registered return address, eliminating reliance on software security mechanisms and their inherent vulnerabilities.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a hardware verification unit as an intermediary between the CPU and the program execution flow. This verification unit acts as a mediator that intercepts and validates program counter values, preventing malicious code execution without requiring changes to the existing software stack.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If hardware-based cryptographic processing is implemented, then security against malicious programs is improved, but device complexity increases

Engineering Contradiction:

Improvesecurity capabilityVSAvoidcircuit complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the security verification function directly into the existing cryptographic processing circuit. The verification unit is integrated with the CPU and cryptographic processor, sharing hardware resources and communication pathways, which reduces overall system complexity while enhancing security.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The verification unit is designed to work with any program executing cryptographic functions, making it a universal security mechanism. It can verify legitimacy for different cryptographic operations (encryption, decryption, signing) without requiring separate verification circuits for each function.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS11526598B2Microcontroller and semiconductor device

Publication Date: 2022.12.13 RENESAS ELECTRONICS CORP

AI summary

A microcontroller includes a CPU and a cryptographic circuit, and when a first program uses the cryptographic circuit, the second program transmits installation information of the first program and encrypted program installation information to the cryptographic circuit. The cryptographic circuit decrypts the encrypted program installation information and compares it with the installation information of the first program. In the case of match, the use of the cryptographic circuit by the first program is permitted.