Remote Query Interface for Safety Control Signal Isolation

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Solution Overview

Problem

Existing security systems face challenges in allowing remote querying of data from control devices while preventing manipulation and ensuring the integrity of query commands, particularly in safety-critical applications like railway technology where high safety standards are mandatory.

Innovation Solution

An interface device is connected to the control device, featuring a test device that checks received remote query signals for permissible interrogation commands and only forwards those, blocking other control commands, ensuring the control device is protected from direct access. This interface device can have multiple stages with different transmission protocols and includes a data diode for unidirectional data transmission, and a signature memory for validating software updates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If remote querying is enabled to allow external access to system data, then data accessibility and monitoring capability are improved, but system security and protection against unauthorized manipulation deteriorate

Engineering Contradiction:
Improveremote data querying capabilityVSAvoidsystem security against manipulation
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

An interface device is introduced as an intermediary component between the external remote query device and the control device. This interface device receives query signals from external devices, validates them against stored admissible query commands, and only forwards validated commands to the control device. This mediator architecture enables remote querying while protecting the control device from direct external access and potential manipulation.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If direct external access to control device is permitted for remote querying, then operational flexibility and remote monitoring are improved, but protection against unauthorized control signals deteriorates

Engineering Contradiction:
Improveremote access flexibilityVSAvoidunauthorized control signals
Core Design Contradiction:
Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The interface device performs preliminary validation of incoming query signals before they reach the control device. By checking whether received query commands match stored admissible query commands in advance, the system prevents unauthorized control signals from ever reaching the control device, thus maintaining operational flexibility while blocking harmful factors beforehand.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If query commands are validated before forwarding to control device, then system security and integrity are improved, but device complexity and processing overhead increase

Engineering Contradiction:
Improvequery command integrityVSAvoidinterface device structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The interface device stores copies of admissible query commands in its memory. Instead of implementing complex validation logic, the device simply compares incoming query signals against these pre-stored command copies. This copying approach enables reliable query validation while keeping the interface device structure relatively simple and avoiding excessive processing overhead.

Inventive Principle:
Principle #26Copying

Data Source

PatentEP3475143B1Arrangement having a safety-related system and method for the protected operation thereof by means of a remote query
Publication Date: 2021.08.25 SIEMENS MOBILITY GMBH
  • EP3475143B1 patent drawingFigure 1
  • EP3475143B1 patent drawingFigure 2
  • EP3475143B1 patent drawingFigure 3

AI summary

The invention relates, inter alia, to an arrangement having a technical system (10), in particular a safety-related system (10), and a control device (20) which controls the system (10) and can change the technical state of the system (10) by means of control commands (SB). The invention provides for an interface device (30) to be connected to the control device (20), which interface device forms an external interface for connection to an external remote query device (40), wherein the interface device (30) has a checking device (31) which is configured in such a manner that it checks a received remote query signal (FAS(AB)) for the presence of a query command (AB) stored as permissible in the interface device (30) and, in the event of permissibility, forwards only the query command (AB) to the control device (20) and blocks the forwarding of the remote query signal (FAS(AB)) as such or all other control commands which are not query commands (AB) stored as permissible.