Satellite Navigation Signal Authentication via Encrypted Correlation
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Solution Overview
Problem
Users of low-accuracy satellite navigation services are vulnerable to spoofing and meaconing attacks due to the inability to authenticate unencrypted signals, as they cannot verify the trustworthiness of the signals received from satellites.
Innovation Solution
A method is introduced where a receiver correlates a signal sample from an encrypted signal with a received unencrypted signal to authenticate its authenticity, using encrypted signal information that includes a sequence of chips modulated by a pseudorandom number (PRN) code, without needing to decrypt the encrypted signal, thereby determining if the unencrypted signal is genuine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If unencrypted signals are used for public access, then ease of operation is improved, but reliability deteriorates due to vulnerability to spoofing and meaconing attacks
Solution Approach 1:
The patent introduces an encrypted signal as an intermediary authentication mechanism. The receiver correlates the unencrypted signal with the encrypted signal to verify authenticity. The encrypted signal acts as a mediator that proves the source legitimacy without preventing public access to the unencrypted positioning data.
2Reliability
If encrypted signals are used for high-accuracy service, then reliability is improved, but ease of operation deteriorates due to restricted access
Solution Approach 1:
The patent segments the signal service into two layers: an unencrypted accessible layer for public positioning services and an encrypted authentication layer for verifying signal authenticity. This segmentation allows different groups of users to access appropriate service levels while maintaining security through the encrypted signal correlation mechanism.
3Reliability
If signal authentication is implemented, then reliability is improved, but device complexity increases due to correlation processing requirements
Solution Approach 1:
The patent uses copying of the encrypted signal code sequence for correlation purposes. Instead of implementing complex decryption algorithms, the receiver creates a copy of the expected encrypted signal pattern and correlates it with the received signal. This copying approach simplifies the authentication process while maintaining reliability.
Data Source
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AI summary
A method and apparatus for providing information about an encrypted signal transmitted by a satellite in a satellite navigation system are disclosed. A data sequence of the encrypted signal as transmitted is obtained, a signal sample is extracted from the data sequence, the signal sample including a part of the data sequence having a length less than a total length of the data sequence, and the signal sample and information about when the data included in the signal sample was transmitted by the satellite are transmitted, as the encrypted signal information, to a receiver for use in the satellite navigation system. A method and apparatus for authenticating an unencrypted signal based on the encrypted signal information are also disclosed. In particular, a time offset between an internal clock of the receiver and an internal clock of the satellite is obtained based on the unencrypted signal, the encrypted signal information is received, a portion of the received encrypted signal is identified that is expected to correspond to the signal sample based on the obtained time offset, the identified portion is correlated with the signal sample, and it is determined that the received unencrypted signal is authentic if a predetermined threshold correlation is obtained.