Elevator Safety Unit Architecture for Secure Software Updates
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Solution Overview
Problem
Existing security systems for building-bound passenger transport systems face challenges in maintaining simplicity while ensuring secure software updates and protecting against unauthorized access, which complicates certification and may compromise safety.
Innovation Solution
A security system comprising separate security and update units with distinct hardware and software, where the update unit handles external communication and encryption, ensuring secure software updates are transmitted internally to the security unit, which maintains minimal and secure software, reducing complexity and the need for external interface complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an external interface is added to the security unit for software updates, then software can be updated externally, but the complexity of the security unit increases
Solution Approach 1:
The system is divided into a security unit and a separate update unit. The security unit maintains its simplicity for safety-critical functions, while the update unit handles all external communication and software update operations. This segmentation allows the security unit to remain simple and certifiable while still enabling external software updates through the dedicated update unit.
2Ease of operation
If the security unit handles external communication directly, then update functionality is integrated, but protection against unauthorized access is reduced
Solution Approach 1:
The update unit serves as an intermediary between the external environment and the security unit. It handles all external communication, authentication, and software reception, then securely transfers only validated updates to the security unit through a protected internal interface. This intermediary role isolates the security unit from external threats while enabling update operations.
3Reliability
If the security unit has complex software for encryption and authentication, then security is enhanced, but certification becomes more difficult and expensive
Solution Approach 1:
Complex software functions for encryption, authentication, and external communication are extracted from the security unit and placed in the separate update unit. The security unit retains only simple, safety-critical software that is easier to certify, while the update unit handles all complex security-related software operations externally.
Data Source
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AI summary
A safety system (36) for a building-related passenger transport system (10) comprises a safety unit (40) for receiving safety-relevant signals from components (26) of the passenger transport system (10) and for triggering a safety measure; and an updating unit (38) for receiving updated software (50) via an external interface (42) and for transmitting the updated software (50) to the safety unit (40) via an internal interface (52).