Safety Program Signature Codes for Document Integrity Verification
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Solution Overview
Problem
There is a need for a configuration that ensures stricter handling of safety program documents executed in safety controllers, particularly to prevent page falsification and inconsistencies between the safety program on a personal computer and the safety controller, which is crucial for evaluating functional safety.
Innovation Solution
A program development support device that generates and outputs documents with a signature code calculated based on the safety program data, ensuring that even slight modifications change the signature code, thereby preventing page falsification and ensuring document integrity by providing the identification value uniformly across all related pages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If online editing is performed to directly modify the safety program on the safety controller, then the safety program can be updated in real-time, but the safety program on the safety controller becomes inconsistent with the safety program on the personal computer
Solution Approach 1:
The patent applies preliminary action by generating a signature code from the safety program data on the personal computer before transferring it to the safety controller. This signature code serves as a preliminary verification mechanism that ensures any subsequent modifications to the program can be detected, preventing inconsistency between the PC and controller versions.
Solution Approach 2:
The patent implements feedback by comparing the signature code generated from the safety program on the personal computer with the signature code stored on the safety controller. This feedback mechanism detects any modifications made through online editing, allowing the system to identify and prevent program inconsistency.
2Ease of operation
If the safety program document is easily modified, then the document can be updated conveniently, but the document may be falsified or become inconsistent with the actual program
Solution Approach 1:
The patent applies preliminary action by embedding a signature code in the safety program document before it is distributed or viewed. This signature code acts as a preliminary security measure that remains valid only as long as the document matches the actual safety program, preventing undetected falsification.
Solution Approach 2:
The patent implements feedback by providing a verification function that compares the signature code in the document with the signature code generated from the actual safety program data. This feedback mechanism allows users to verify document integrity, ensuring that any falsification or inconsistency can be detected.
3Reliability
If a signature code is generated and provided to all pages of the safety program document, then document falsification can be prevented, but the document verification process becomes more complex
Solution Approach 1:
The patent applies copying by generating a signature code that is a derived representation of the safety program data. This signature code is then copied to all pages of the document, serving as a distributed verification marker that can be checked without requiring access to the entire program source code.
Solution Approach 2:
The patent uses the signature code as an intermediary element that mediates between the complex safety program data and the simple verification process. The signature code translates the complex program into a verifiable form, allowing verification without requiring deep analysis of the program logic.
Data Source
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AI summary
A program development support device (100) for supporting development of a safety program (300) to be executed in a safety controller (200) includes: development means (124) for developing the safety program in response to user operation; calculation means (150) for calculating an identification value according to data of the developed safety program, in accordance with a function for calculating a random value with respect to an input; and output means (126) for outputting a document related to the safety program. The output means provides the identification value calculated by the calculation means to all pages of the document which are related to the safety program.