Access Control Clock Synchronization with State-Based Security Checks
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Solution Overview
Problem
Access control devices, particularly battery-operated locks, face challenges in synchronizing clocks due to significant time deviations, which can be exploited for unauthorized access, and existing methods lack robustness against manipulation.
Innovation Solution
A method involving a series of checks to ensure synchronization only occurs under specific conditions, including verifying the device's state after initial operation, battery change, or reset, and ensuring the time deviation is within a predefined threshold, preventing abusive synchronization attempts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If clock synchronization is performed using communicated time information, then time accuracy is improved, but security against manipulation deteriorates
Solution Approach 1:
The system performs preliminary checks before synchronization to detect device states (initial operation, battery change, reset) and validates the plausibility of time deviations. These preliminary actions prevent malicious synchronization attempts by establishing safety conditions before the actual time update occurs.
Solution Approach 2:
The system uses feedback from previous synchronization operations and device state information to dynamically adjust synchronization behavior. By analyzing whether the device is in a vulnerable state and comparing time deviations against expected thresholds, the system feedback-controls whether to accept or reject time information, thereby maintaining security while ensuring accuracy.
2Reliability
If multiple synchronization checks are performed, then security is improved, but device complexity increases
Solution Approach 1:
The synchronization process is segmented into distinct check stages: device state detection, time deviation validation, and conditional synchronization execution. Each segment handles a specific aspect of security validation, making the overall complex process manageable and maintainable while ensuring comprehensive security checks.
3Measurement precision
If time deviation threshold is set low, then synchronization accuracy is improved, but synchronization reliability deteriorates
Solution Approach 1:
The system dynamically adjusts the effective threshold for accepting time information based on device state. In normal operation, stricter thresholds maintain accuracy, while in vulnerable states (initial operation, battery change, reset), the system temporarily allows larger deviations to ensure successful synchronization, then returns to stricter validation afterward.
Data Source
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AI summary
The invention relates to, among others, a method which is carried out using a first device (69). The method has the steps of obtaining temporal information communicated to the first device (69); carrying out one or more of the following tests: a test to determine whether the first device (69) is in a state following an initial operation, a battery replacement or other power outage, or a reset, a test to determine whether a deviation between temporal information of the clock and the communicated temporal information is less than or less than or equal to a threshold which is specified or determined according to a specified rule, and a test to determine whether the communicated temporal information has the same date as the temporal information of the clock; and synchronizing the clock using the communicated temporal information if all of one or more defined conditions are satisfied, wherein one of the one or more conditions requires that at least one of the one or more test(s) carried out has a positive result. The invention further relates to a corresponding method carried out on a second device (68, 61), to computer programs assigned to the methods, and to a system (6) which comprises said devices (61, 68, 69).