Moveable Barrier RF Code Shifting Against Signal Interception
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Solution Overview
Problem
Existing security systems for moveable barriers, such as garage doors, are vulnerable to unauthorized access due to interception and duplication of rolling codes, and require inconvenient mechanical or radio-controlled methods that pose safety and usability issues.
Innovation Solution
A security system employing a transmitter and receiver that communicate via codes with a shifting sequence position, using a combination of fixed and changing codes, and additional encryption measures to prevent code interception and ensure secure communication between devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical lock and key arrangements are used, then security against tampering is improved, but ease of operation deteriorates due to requiring user to exit vehicle
Solution Approach 1:
The patent replaces the mechanical lock and key system with a wireless radio frequency communication system. The transmitter sends coded signals through radio waves to the receiver, eliminating the need for physical keys and mechanical locks, thus maintaining security while dramatically improving ease of operation.
Solution Approach 2:
The patent introduces radio frequency signals as an intermediary between the user and the barrier operator. Instead of direct mechanical interaction with a lock, the user simply presses a button on a remote transmitter, and the coded radio signal mediates the authentication and actuation process.
2Ease of operation
If radio frequency signals with rolling codes are used, then ease of operation is improved, but security deteriorates due to vulnerability to code interception and duplication
Solution Approach 1:
The patent employs rolling codes that dynamically change with each transmission. Instead of using a static code that can be intercepted and reused, the system generates new codes based on a counter or timestamp, making each transmission unique and preventing replay attacks by intercepting signals.
Solution Approach 2:
The patent implements periodic code changes where the rolling code increments or transforms with each actuation of the transmitter. This periodic regeneration of codes ensures that even if an attacker intercepts a signal, the code becomes obsolete after a single use, maintaining security while preserving the convenience of wireless operation.
3Reliability
If code hopping encoders with window forward systems are used, then reliability is improved by preventing out-of-sync transmitters, but device complexity increases
Solution Approach 1:
The patent pre-configures both the transmitter and receiver with the same initial rolling code and synchronization state. Before each transmission, the system ensures that the code and timing are properly aligned through preliminary synchronization mechanisms, preventing out-of-sync conditions without requiring complex real-time adjustments.
Data Source
AI summary
Electronic systems are provided for secure actuation of a remote device such as a moveable barrier operator. The systems address the “man in the middle” problem of persons intercepting and duplicating radio frequency signals from a control device by offsetting one or more portions of a message in order to obscure content of the message.