Browser Certificate Validation Against Root CA List Tampering

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Solution Overview

Problem

Existing web browsers are vulnerable to man-in-the-middle attacks due to manipulation of trusted root certificate authority lists by malicious actors.

Innovation Solution

Configuring web browsers to validate certificates using predefined invalidation criteria, including checking if the root certificate authority was included in the system at installation time and maintaining a separate list of trusted authorities provided by an administrator, and ceasing communication with parties that violate these criteria.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If SSL/TLS certificates are used to secure web communications, then security against eavesdropping is improved, but vulnerability to man-in-the-middle attacks using spoofed certificates remains

Engineering Contradiction:
ImprovesecurityVSAvoidman-in-the-middle attack vulnerability
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The system performs preliminary validation of SSL certificates by checking them against multiple trusted Certificate Authorities before allowing web content to load. This advance verification prevents man-in-the-middle attacks by ensuring certificates are genuinely trusted before the browser establishes secure connections.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention introduces an intermediary validation layer between the browser and web servers, using multiple trusted Certificate Authorities as mediators to verify certificate authenticity. This intermediary system detects and blocks spoofed certificates that would otherwise enable man-in-the-middle attacks.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If multiple Certificate Authorities are integrated for certificate validation, then detection of spoofed certificates is improved, but system complexity increases

Engineering Contradiction:
Improvecertificate validation accuracyVSAvoidsystem architecture complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The validation system is designed with multi-functionality to handle multiple Certificate Authorities simultaneously through a unified interface. This universal approach allows the same validation mechanism to work with different CAs without requiring separate complex validation paths for each authority.

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

Solution Approach 2:

The invention combines multiple Certificate Authority validation processes into a single integrated validation system. By merging the validation logic and presenting a unified interface to browsers, the system achieves high validation accuracy while minimizing the complexity that would otherwise arise from managing multiple separate validation mechanisms.

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If SSL certificate validation is performed for all web content, then security against drive-by downloads is improved, but page load time increases

Engineering Contradiction:
ImprovesecurityVSAvoidpage load time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The system applies partial validation by prioritizing security checks for critical resources while allowing less critical content to load with reduced validation overhead. This selective approach maintains security against drive-by downloads while minimizing the impact on overall page load performance.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The validation system performs preliminary checks on SSL certificates during the initial connection phase, allowing subsequent content to load more quickly. By completing essential security validation before full page rendering begins, the system ensures security without significantly impacting user-perceived load times.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP4449672B1Defending web browsers against man-in-the-middle attacks
Publication Date: 2026.05.06 ISLAND TECH INC
  • EP4449672B1 patent drawingFigure 1A
  • EP4449672B1 patent drawingFigure 1B
  • EP4449672B1 patent drawingFigure 1C

AI summary

A computer network security method implemented by configuring a web browser to determine whether a root certificate authority appears in a first list of trusted root certificate authorities that is maintained by an operating system of a host computer that hosts the web browser, determine whether the root certificate authority was included in the first list at the time that the operating system was installed on the host computer or was thereafter included in the first list by the operating system, determine whether the root certificate authority appears in a second list of trusted root certificate authorities that is provided to the web browser by an administrator, determine whether a certificate meets predefined invalidation criteria, and cease to communicate with a party that provided the certificate to the web browser responsive to the web browser determining that the certificate meets the predefined invalidation criteria.