Certificate Authentication Using Positive List Verification

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Solution Overview

Problem

Existing digital certificate authentication methods in automation systems lack clarity on whether validation is based on a white list, leading to potential security vulnerabilities as devices may be authorized without thorough verification.

Innovation Solution

Incorporating admissibility information into the message that includes signature verification and white list determination, ensuring both checks are conducted and communicated, with additional parameters like issuer, age, and application environment to restrict whitelist usage, thereby enhancing security.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If digital certificate authentication is performed without white list checking, then authentication speed is improved, but security is worsened

Engineering Contradiction:
Improveauthentication speedVSAvoidsecurity
Core Design Contradiction:
SpeedVSReliability

Solution Approach 1:

The white list is pre-generated and stored before authentication occurs. The authenticating unit retrieves the appropriate white list from storage and performs checking as part of the standard authentication flow, eliminating the need for real-time external reference checks while maintaining security.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary structure where the white list acts as a mediator between the certificate and the authentication decision. The white list contains pre-processed allowed certificates or characteristics, enabling efficient comparison without requiring complex real-time validation logic.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If white list checking is performed for every certificate, then security is improved, but authentication complexity is worsened

Engineering Contradiction:
ImprovesecurityVSAvoidauthentication complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The authentication process is segmented into distinct phases: certificate retrieval, white list selection based on device context, and verification. This segmentation allows each component to be optimized independently and makes the overall process more manageable and maintainable.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system changes the parameter of white list selection based on device context, such as device type, location, or application requirements. Different white lists or white list subsets are applied depending on the specific authentication scenario, simplifying the verification process for each context rather than using a single complex universal check.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If admissibility information is added to messages, then authorization security is improved, but message size is worsened

Engineering Contradiction:
Improveauthorization securityVSAvoidmessage size
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The white list data is extracted and stored separately from the authentication messages. Only references or summaries of the white list (such as identifiers or hashes) are included in messages, while the full white list content is stored externally and accessed as needed during authentication.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The admissibility information is nested within the message structure in a compact format, with the white list references contained within the admissibility field. This nested structure allows efficient storage and transmission while maintaining the necessary security information.

Inventive Principle:
Principle #7Nested doll (Nesting)

Data Source

PatentEP3111609B1Use of certificates using a positive list
Publication Date: 2024.02.21 SIEMENS AG
  • EP3111609B1 patent drawingFigure 1~3
  • EP3111609B1 patent drawingFigure 4
  • EP3111609B1 patent drawingFigure 5

AI summary

The invention relates to methods and apparatuses for using certificates (ZERT) using a positive list (WL). This involves a message (VMSG), wherein the message (VMSG) comprises a certificate (ZERT) for a device (G), the certificate (ZERT) has a signature (SIG) for checking (PROOF1) an authenticity of the certificate (ZERT) and a piece of admissibility information (ZINFO) for ascertaining (PROOF2) an admissibility of the certificate (ZERT) using a positive list (WL), being taken as a basis for carrying out authorisation for the device (G) subject to the check and the ascertainment. The invention can be used in industrial or medical environments.