BLE Frame Sync Frequency Offset for Spoof-Resistant Ranging
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Solution Overview
Problem
BLE distance estimation techniques are susceptible to spoofing attacks, compromising the security of keyless entry systems by allowing unauthorized access to enclosures.
Innovation Solution
Implementing a security signature through random frequency offset generation and detection in BLE frame synchronization, where a frequency offset is added to frame synch packets, which are encrypted and verified by the receiving device to ensure authenticity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If RTT-based ranging technique is used for BLE distance estimation, then distance measurement capability is improved, but security against spoofing attacks deteriorates
Solution Approach 1:
The patent changes the parameter being measured from time-based (RTT) to frequency-based (frequency offset). By transmitting frequency offset information in the packet payload and measuring the frequency difference between transmitted and received packets, the system achieves distance estimation while the random frequency offset acts as a security signature that prevents spoofing attacks.
Solution Approach 2:
The patent introduces frequency offset information as an intermediary element. This intermediary carries both the distance measurement data and the security signature function, allowing the system to simultaneously achieve accurate ranging and spoofing resistance without requiring separate mechanisms.
2Reliability
If frequency offset is added to frame synch packets for security signature, then security against spoofing attacks is improved, but device complexity increases
Solution Approach 1:
The patent makes the frequency offset information serve multiple functions simultaneously: it acts as a security signature to prevent spoofing, carries distance measurement data for ranging, and maintains frame synchronization. This multi-functionality reduces the need for separate security mechanisms and minimizes overall system complexity.
Solution Approach 2:
The patent combines security verification and distance measurement functions into a single frequency offset measurement process. The same frequency offset that provides security authentication also enables ranging, merging two functions into one unified mechanism that reduces processing complexity.
3Reliability
If random frequency offset generation is implemented, then spoofing resistance is improved, but measurement precision may deteriorate due to frequency variations
Solution Approach 1:
The patent applies preliminary frequency offset compensation before distance measurement. The receiving device first compensates for the random frequency offset using the transmitted frequency offset information, then performs accurate frequency difference measurement. This preliminary action removes the security-providing frequency variation that would otherwise degrade measurement precision.
Data Source
AI summary
A wireless device includes a transmitter adapted with Bluetooth® low energy (BLE) capability and logic at least one of coupled to or integrated within the transmitter. The logic randomly generates a frequency offset based on bits within a frame synch packet to be transmitted during a keyless access attempt of an enclosure having a receiver. The logic causes the bits of the frame synch packet to be encrypted with an encryption key. The logic causes a frequency of the frame synch packet to modified by the frequency offset before the transmitter transmits the frame synch packet to the receiver.