Secure Element Memory Integrity Verification via Hash Segmentation

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Solution Overview

Problem

Existing solutions for integrity control in electronic devices, such as card payment systems, fail to ensure comprehensive and secure verification of the entire memory content, leading to potential vulnerabilities from unauthorized modifications and performance bottlenecks during integrity checks.

Innovation Solution

Implementing an integrity control process where a secure element verifies the entire memory content using a public key, allowing the device to operate based on the integrity level observed, with adaptive functionality adjustments, including secure element decision-making on memory access and operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the secure element verifies the entire memory content using public key cryptography, then the integrity control becomes comprehensive and secure, but the processing time and computational load increase significantly

Engineering Contradiction:
Improveintegrity controlVSAvoidverification time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent divides the memory verification process into segments by using a hash function to process memory content in chunks rather than verifying the entire memory content directly with public key cryptography. The hash function processes data in manageable segments, generating a hash value that represents the entire memory content, which is then verified using the public key.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces a hash function as an intermediary between the memory content and the public key verification process. Instead of directly verifying large amounts of memory content with computationally intensive public key cryptography, the system first transforms the memory content into a compact hash value through the intermediary hash function, which is then efficiently verified using public key cryptography.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If the system performs comprehensive integrity checks on all memory content, then unauthorized modifications are detected, but the device complexity and processing overhead increase

Engineering Contradiction:
Improvedetection capabilityVSAvoidprocessing overhead
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the direct mechanical approach of public key cryptography verification with a two-stage process: first using a lightweight hash function (mathematical transformation) to process memory content, then using public key cryptography only on the resulting hash value. This substitution reduces the computational overhead while maintaining detection capability.

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

Solution Approach 2:

The patent changes the parameter being verified from the raw memory content (large data size) to a hash value of the memory content (small data size). This parameter transformation maintains the integrity verification capability while significantly reducing the computational complexity and processing overhead of the public key verification step.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If the secure element controls all functionalities based on integrity verification, then security is enhanced, but the ease of operation and system flexibility decrease

Engineering Contradiction:
ImprovesecurityVSAvoidsystem flexibility
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent implements dynamic control where the secure element adjusts its operational state based on the integrity verification results. When integrity is confirmed, the secure element transitions to a more flexible operational mode with fewer restrictions. When integrity violations are detected, it transitions to a restricted mode, providing adaptive security that balances security requirements with operational flexibility.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the operational parameters of the secure element based on integrity verification results. Instead of maintaining fixed restrictive settings, the system dynamically adjusts parameters such as access permissions, operational modes, and functionality levels according to the verified integrity state, enabling both high security and operational ease when appropriate.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3732604B1Checking the integrity of an electronic device
Publication Date: 2025.04.30 LEDGER SAS
  • EP3732604B1 patent drawingFigure 1~2
  • EP3732604B1 patent drawingFigure 3

AI summary

The method for checking the integrity of an electronic device (DE), in particular a payment terminal, including at least one processor (MPU), a secure element (SE) able to store and manage data and into which a public key that is intended to verify an electronic signature has been loaded, and a data storage means (MEM), whose content has been authenticated beforehand and whose integrity is able to be verified by the public key, is such that a command to check integrity brings about the execution of the following successive steps: the processor (MPU) of the device calls upon the secure element (SE); in response, the secure element (SE) addresses, to the data storage means (MEM), a request for the purpose of receiving the integral content of its memory; the secure element then executes, on the content received from the memory of the data storage means (MEM), an authenticity verification in order to verify, using the public key (KP), that its content has not been able to be modified since its initial authentication; when the authenticity verification succeeds, the device is considered to be integral.