Field Device Authentication Under Location and Time Constraints

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Solution Overview

Problem

Existing technologies face challenges in enforcing operating constraints, such as location and time restrictions, for field devices to ensure compliance with legal requirements and service agreements, as existing methods are difficult to implement effectively.

Innovation Solution

A method where a field device receives a base key from a key generation device and generates a current key based on predefined operating constraints, such as location or timing, ensuring interaction with a control device only within allowed parameters, using asymmetric or symmetric encryption schemes, and logging interactions in a distributed ledger like a blockchain for secure and tamper-proof audit trails.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If operating constraints are enforced through legal contracts and penalties, then compliance is required, but enforcement is difficult

Engineering Contradiction:
Improveconstraint enforcementVSAvoidenforcement difficulty
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The system performs preliminary action by embedding operating constraints directly into the cryptographic key generation process before the device operates. The key generation device incorporates constraint parameters (location, time, usage conditions) into the key material itself, so that compliance is technically enforced rather than legally required. This transforms contractual obligations into technical necessities.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system applies parameter changes by dynamically modifying cryptographic keys based on constraint parameters such as location coordinates, time stamps, and usage conditions. When constraints are violated, the key parameters change to render the device inoperable, providing automatic technical enforcement of operating constraints without requiring external monitoring or legal intervention.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If dynamic key generation based on constraint parameters is implemented, then operating constraints are enforced, but device complexity increases

Engineering Contradiction:
Improveconstraint enforcementVSAvoidkey generation complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system introduces an intermediary key generation device that handles the complex cryptographic operations. This separate device generates keys incorporating constraint parameters and provides them to the field device, which then uses these keys for normal operations. This intermediary approach centralizes the complexity in a dedicated component while keeping the main field device relatively simple.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The system segments the key management functionality by separating key generation from key usage. The key generation device handles the complex task of incorporating constraint parameters into cryptographic keys, while the field device focuses on using these keys for operations. This segmentation allows each component to be optimized independently, reducing overall system complexity.

Inventive Principle:
Principle #1Segmentation

3Adaptability or versatility

If encrypted activation codes are used for enabling functionalities, then custom functionalities can be enabled, but constraint enforcement remains difficult

Engineering Contradiction:
Improvefunctionality enablementVSAvoidconstraint enforcement
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The system merges the functionality enablement mechanism with the constraint enforcement mechanism by incorporating operating constraints directly into the cryptographic key material. The same key that enables custom functionalities also embeds location, time, and usage constraints, so that enabling features and enforcing compliance become unified rather than separate processes.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP3853676B1Constrained operation of a field device
Publication Date: 2024.09.11 SIEMENS AG
  • EP3853676B1 patent drawingFigure 1
  • EP3853676B1 patent drawingFigure 2
  • EP3853676B1 patent drawingFigure 3

AI summary

The present application relates to a method for operating a field device (101). The field device (101) is configured for interacting with a control device (102). According to the method, a base key is received (201) from a key generation device (103). A current constraint parameter relating to a predefined operating constraint for operating the field device (101) is determined (202). A key is generated (204) based on the base key and the current constraint parameter. The field device (101) interacts (205) with the control device (102) using the generated key.