Secure Device Verifies Bootloader Signature for Non-Secure Systems

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Solution Overview

Problem

Non-secure computer devices lack the capability of a root of trust, making them vulnerable to attacks and data integrity issues during the secure boot process, leading to potential damage or illegal modifications.

Innovation Solution

A computing system comprising a secure device with a root of trust module that verifies the signature of a bootloader for a non-secure device, allowing the secure device to transmit an activation signal after successful verification, thereby establishing a chain of trust and ensuring the integrity of the boot process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a non-secure device is used without RoT capability, then device complexity is reduced and cost is lowered, but security reliability deteriorates and the device becomes vulnerable to attacks

Engineering Contradiction:
Improvedevice complexityVSAvoidsecurity reliability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent introduces a secure device as an intermediary that performs the RoT verification function externally. The secure device stores the bootloader signature, verifies the bootloader integrity, and controls the activation signal transmission. This mediator approach allows non-secure devices to benefit from security verification without requiring embedded RoT capabilities, resolving the contradiction between reduced device complexity and maintained security reliability.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If secure verification is implemented in every device, then security reliability is improved, but device complexity and manufacturing cost increase

Engineering Contradiction:
Improvesecurity reliabilityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent creates a universal security verification system where a separate secure device can serve multiple non-secure devices. The secure device contains the RoT capability and can verify bootloaders for different non-secure devices, making the security function universal rather than device-specific. This reduces the need for every device to have embedded RoT capabilities, thereby reducing overall system complexity while maintaining security reliability.

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

3Reliability

If the secure device verifies bootloader signature before activation, then data integrity is improved and unauthorized modifications are prevented, but the boot process time increases

Engineering Contradiction:
Improvedata integrityVSAvoidboot process time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent implements preliminary verification where the secure device checks the bootloader signature before allowing activation. By performing the security verification in advance during the boot process rather than during operation, the system ensures data integrity while minimizing the impact on overall system performance. The verification is integrated into the boot sequence, allowing parallel processing where possible.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3989478B1Computing system and device for handling a chain of trust
Publication Date: 2023.10.18 MOXA INC
  • EP3989478B1 patent drawingFigure 1
  • EP3989478B1 patent drawingFigure 2
  • EP3989478B1 patent drawingFigure 3

AI summary

A computing system for handling a chain of trust comprises a non-secure device comprising a receiving module, for receiving a signal for activating the non-secure device; and a secure device, coupled to the non-secure device, comprising a root of trust (RoT) module, for verifying at least one first signature of a bootloader for the non-secure device, wherein the bootloader is stored in the RoT module; and a transmitting module, coupled to the RoT module, for transmitting the signal to the receiving module to activate the non-secure device, after the at least one first signature is verified as successful.