Flash Memory Hash Verification for Faster Vehicle Signature Checks

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Solution Overview

Problem

Existing methods for verifying digital signatures in flash memory are time-consuming, slowing down the boot process and software updates in vehicles with complex computing units.

Innovation Solution

A method where hash values are pre-calculated and stored in flash memory by the memory controller, allowing for faster signature verification by applying a hash function to these stored hashes instead of recalculating them from the data.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a microcontroller unit is used to check digital signatures, then the system can verify software authenticity, but the microcontroller may be compromised by malicious software, leading to false verification results

Engineering Contradiction:
Improveverification result accuracyVSAvoidmicrocontroller compromise
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A dedicated hardware module is introduced as an intermediary between the microcontroller and the digital signature verification process. This hardware module performs the cryptographic verification operations independently, ensuring that even if the microcontroller is compromised, the verification results remain trustworthy. The hardware module acts as a secure mediator that isolates the verification function from potential software vulnerabilities.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If digital signature verification is performed using existing microcontroller units, then software authenticity can be checked, but the microcontroller's processing power is insufficient for complex cryptographic operations

Engineering Contradiction:
Improvecryptographic verification capabilityVSAvoidprocessing power requirement
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the software-based cryptographic processing approach with a dedicated hardware implementation. Instead of relying on the microcontroller's general-purpose processing units to perform complex cryptographic operations, a specialized hardware module is deployed that is optimized for digital signature verification. This hardware substitution provides the necessary processing power and cryptographic strength without requiring the microcontroller to be overly complex.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If a dedicated hardware module is added for digital signature verification, then verification reliability is improved, but the system complexity and cost increase

Engineering Contradiction:
Improveverification result accuracyVSAvoidsystem structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The dedicated hardware module is designed with multi-functionality to justify its addition to the system. It not only performs digital signature verification but also handles related cryptographic operations such as hash computation and key management. By making the hardware module universal for various cryptographic tasks, the system achieves improved verification reliability while minimizing the overall increase in complexity through a single versatile component rather than multiple specialized modules.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP4275138B1Method for checking digital signatures, vehicle computing unit and vehicle
Publication Date: 2026.05.20 MERCEDES BENZ GROUP AG
  • EP4275138B1 patent drawingFigure 1~2
  • EP4275138B1 patent drawingFigure 3

AI summary

The invention relates to a method for checking digital signatures, wherein a hash which is processed to generate a signature is created by applying a hash function to data stored in a flash memory (1). The invention is characterised by at least the following method steps: - writing data to at least one memory element (1.1) of the flash memory (1); - for each written block (2) of the flash memory (1): calculating a hash from the data written to each block (2) by means of a memory controller (1.2) of the flash memory (1) and storing the calculated hash together with the data in the block (2); - calculating a verification hash (#V) by applying a hash function to at least one hash stored in a block (2), by means of the memory controller (1.2); - reading out at least one hash stored in a block (2) and the verification hash (#V) for the blocks (2) of which the signature is to be checked, by means of a system (3) which is superordinate to the flash memory (1); - calculating a check hash (#P) by applying a hash function to the at least one read-out hash by means of the system (3) which is superordinate to the flash memory (1); - comparing the calculated check hash (#P) with the read-out verification hash (#V); - and, if the check hash (#P) matches the verification hash (#V): confirming the signature.