Vehicle Timestamp Validation Against Roll Jammer Attacks
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Solution Overview
Problem
Wireless communication systems between vehicles and key fobs are vulnerable to roll jammer attacks, which exploit the rolling code authentication mechanism by replaying valid signals at a later time, allowing unauthorized access.
Innovation Solution
Incorporating a timestamp into the wireless signals and using a time window that expands as a trigonometric function of the counted time and a predetermined angle to validate the timestamp, ensuring that signals must be received within a limited timeframe to prevent unauthorized access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rolling code authentication is used, then security against replay attacks is improved, but vulnerability to roll jammer attacks increases due to signal interception and rebroadcasting
Solution Approach 1:
The system performs preliminary actions by establishing a trusted time synchronization relationship between the vehicle and key fob before authentication. The vehicle stores a reference timestamp from the key fob, and subsequent timestamps are validated against this reference with an expanding time window, preventing replay attacks before they can succeed
Solution Approach 2:
The patent introduces time synchronization as an intermediary mechanism between the rolling code authentication system and the key fob. By using timestamps and time window validation, the system creates an additional layer of verification that mediates between the rolling code and the final authentication decision, blocking roll jammer attacks
2Object-affected harmful factors
If a fixed time window is used for timestamp validation, then attack prevention is improved, but clock skew between devices causes authentication failures
Solution Approach 1:
The time window is made dynamic rather than fixed. It expands over time according to a predetermined function, allowing the validation range to adapt to accumulating clock skew between the vehicle and key fob. This dynamic adjustment maintains security while accommodating timing drift
Solution Approach 2:
The system changes the time window parameter from a fixed value to a variable that evolves over time. The expanding time window adjusts the acceptance range for timestamps based on the elapsed time since the last successful authentication, balancing security requirements with clock synchronization realities
Data Source
AI summary
A vehicle includes: receiver(s), a timer counting time, memory, and processor(s) configured to: receive a timestamped signal from a fob; compare the timestamp to a time window; reject the timestamp if the timestamp is outside the time window; expand the time window with the counted time; compute the time window as a trigonometric function of the counted time and a predetermined angle.