Base Station Interference Signal for Key Fob Security
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Solution Overview
Problem
Keyless entry vehicles are vulnerable to unauthorized access due to LF challenge amplification attacks, where attackers use amplifiers to extend the range of LF challenge signals, potentially triggering responses from key fobs stored indoors or away from the vehicle, and existing solutions like shielding the key fob are inconvenient or ineffective.
Innovation Solution
A base station equipped with a transceiver and processor that detects the presence of a key fob and broadcasts a low-level LF interference signal to prevent it from responding to challenge requests, while also indicating the activation of this interference to the user, thereby thwarting LF challenge amplifier attacks without draining the key fob's battery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the key fob is kept in a shielded location to prevent unauthorized access, then security against LF challenge amplification attacks is improved, but convenience of access is worsened
Solution Approach 1:
A base station acts as an intermediary between the vehicle and the key fob. The base station receives challenge requests from the vehicle, forwards them to the key fob, and relays responses back. This mediator approach allows the key fob to remain in a secure location (such as a shielded container or safe) while still enabling authenticated access to the vehicle, thus resolving the contradiction between security and convenience.
2Reliability
If the key fob continuously monitors for challenge requests, then response capability is improved, but battery consumption is worsened
Solution Approach 1:
Instead of continuous monitoring, the key fob employs periodic or event-triggered monitoring for challenge requests. The fob can be configured to wake up at intervals or activate only when certain conditions are met (such as detecting the presence of the vehicle or receiving a wake-up signal). This periodic action maintains the ability to respond to challenges while significantly reducing overall battery consumption compared to continuous operation.
3Reliability
If an interference signal is broadcast to block challenge requests, then protection against attacks is improved, but interference with legitimate communication is worsened
Solution Approach 1:
The interference signal is applied locally and selectively rather than broadly. The base station broadcasts the interference signal only in the specific frequency range and spatial region where LF challenge amplification attacks are detected or expected. This localized application of interference protects against attacks while minimizing impact on legitimate communications occurring in different frequency bands or locations, thus resolving the contradiction between protection and interference.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively prevents unauthorized access by ensuring the key fob cannot receive LF challenge requests from the vehicle or amplifiers, maintaining compatibility with existing key fobs and not causing undesirable interference, while providing a secure location for the key fob when not in use.
Implementation Method 1
broadcast an interference signal using the transceiver to prevent the key fob from hearing or responding to challenge requests
Data Source
AI summary
A base station may include a transceiver, an indicator, and a processor programmed to detect presence of a key fob using one or more inputs. When the key fob is detected, the processor may direct the transceiver to broadcast an interference signal using the transceiver to prevent the key fob from detecting and responding to challenge requests and set the indicator to indicate presence of the broadcast. When an access request is received from a modem, using the transceiver the base station may temporarily discontinue broadcast of an interference signal to send a challenge request to the key fob and receive a challenge response, and send a response to the access request including information based on the challenge response.