Microprocessor ALU Integrity Verification Using Seed Key Pairs

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Solution Overview

Problem

Existing automotive electronic control systems face challenges in verifying the integrity of main microprocessors within the required 200 millisecond diagnostic time window, especially when relying on another main microprocessor instead of a dedicated secondary microprocessor, which can lead to increased diagnostic time and potential safety risks.

Innovation Solution

A system and method that utilize a seed key pair (SKP) transmitted over a distributed vehicle network to verify the integrity of a main microprocessor, eliminating the need for bidirectional requests and incorporating Active Rolling Count, Protection Value, and Message Timeout Event implementations to ensure safety critical signal protection and efficient integrity verification across multiple ECUs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a dedicated secondary microprocessor is used to verify the integrity of the main microprocessor, then the reliability of integrity verification is improved, but the device complexity and cost increase

Engineering Contradiction:

Improveintegrity verification reliabilityVSAvoidsystem complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the integrity verification function from a dedicated secondary microprocessor and implements it within the main microprocessor itself using self-diagnostic routines. The main microprocessor executes verification algorithms, performs ALU integrity tests, and monitors its own operational correctness without requiring a separate verification processor, thereby reducing system complexity while maintaining verification reliability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The main microprocessor performs self-verification by executing diagnostic routines that monitor its own operational integrity. The system uses self-diagnostic capabilities where the microprocessor verifies its own ALU operations, compares expected versus actual results, and detects integrity failures autonomously, eliminating the need for external verification hardware

Inventive Principle:

Principle #25Self-service

2Measurement precision

If bidirectional requests are used for integrity verification, then the verification accuracy is improved, but the diagnostic time exceeds the 200 millisecond requirement

Engineering Contradiction:

Improveverification accuracyVSAvoiddiagnostic time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The system pre-calculates and stores expected verification results in memory before actual verification is needed. When verification is required, the main microprocessor retrieves these pre-computed expected values and compares them against actual ALU operations, eliminating the need for time-consuming bidirectional communication and complex real-time verification protocols

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements a streamlined verification process that skips unnecessary bidirectional request-handling steps. The system performs verification unidirectionally by having the main microprocessor execute diagnostic routines and compare results against pre-stored expected values, rapidly completing verification within the 200-millisecond diagnostic window without prolonged communication exchanges

Inventive Principle:

Principle #21Skipping (Rushing through)

3Ease of operation

If main microprocessors monitor each other over the CAN bus, then the ease of operation is improved, but the diagnostic time increases and safety risks arise from communication protocol interference

Engineering Contradiction:

Improvemonitoring implementation easeVSAvoidsafety integrity

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent extracts the verification process from the CAN bus communication domain and relocates it to internal microprocessor operations. Instead of relying on inter-processor communication over the external bus, the main microprocessor performs verification internally using its own computational resources and pre-stored reference data, isolating the verification process from communication protocol interference and timing constraints

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The system introduces pre-calculated expected verification results stored in memory as an intermediary between the verification request and the actual verification process. This intermediary layer allows the main microprocessor to perform rapid comparisons without requiring real-time communication with other processors, eliminating CAN bus timing issues while maintaining verification capability

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS9268953B2Method of performing microprocessor ALU integrity test over a distributed asynchronous serial communication network for ASIL-D level safety critical applications

Publication Date: 2016.02.23 GM GLOBAL TECHNOLOGY OPERATIONS LLC

AI summary

A system includes first and second modules of a vehicle. The first module stores at least one seed value, calculates a key based on the at least one seed value, forms a seed key pair based on the calculated key and the at least one seed value, generates a data bus message including the seed key pair and data corresponding to operation of the first module, and transmits, over a distributed vehicle network, the data bus message. The second module receives the data bus message over the distributed vehicle network, retrieves the seed key pair from the data bus message, determines whether the calculated key matches an expected key, and selectively verifies integrity of the first module based on the determination of whether the calculated key matches the expected key.