External Cryptographic Assistance for Encrypted GNSS Receivers
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Solution Overview
Problem
The operational overhead of managing keys and cryptographic algorithms for encrypted GNSS receivers is significant, limiting the use of encrypted GNSS signals due to high costs and complexity, particularly for civilian applications that cannot justify the additional expense of security modules.
Innovation Solution
A device that receives encrypted GNSS signals and replica spreading codes from an external source, processing them to calculate a position fix without the need for a security module, using assistance messages to identify satellite identifiers and reduce false correlation detection events through correlation techniques and navigation information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a security module with cryptographic algorithms is integrated into each GNSS receiver to process encrypted signals, then the receiver can calculate position using encrypted GNSS signals, but the device complexity and operational overhead increase significantly
Solution Approach 1:
The patent extracts the cryptographic algorithm and security module from the GNSS receiver and relocates it to an external source. The receiver only retains the capability to receive encrypted signals and process correlation results, while the complex security module resides externally, providing cryptographic assistance without being integrated into the receiver itself.
Solution Approach 2:
The patent introduces an intermediary system (external source) that acts as a mediator between the encrypted GNSS signals and the receiver. This intermediary generates cryptographic assistance information including replica spreading codes and provides them to the receiver, eliminating the need for the receiver to contain its own security module.
2Reliability
If each GNSS receiver is equipped with its own security module and cryptographic keys, then secure access to encrypted signals is ensured, but the operational overhead and cost increase significantly
Solution Approach 1:
The patent makes the external source universal by enabling it to serve multiple GNSS receivers simultaneously. Instead of each receiver having its own dedicated security module, a single external source provides cryptographic assistance to multiple receivers, reducing overall operational overhead and cost while maintaining security.
Solution Approach 2:
The patent uses copying by generating replica spreading codes at the external source and transmitting them to receivers. These replicas are copies of the encrypted spreading codes that allow receivers to perform correlation without needing to generate or store the original cryptographic keys locally.
3Reliability
If conventional encrypted GNSS receivers are used, then position calculation is possible, but the cost of procuring and operating receivers with security modules is prohibitive for civilian applications
Solution Approach 1:
The patent replaces expensive, permanent security modules with a more economical approach where cryptographic functionality is provided externally. The receiver itself can be manufactured at a lower cost without integrated security hardware, while the cryptographic services are provided as external utilities that can be updated or revoked as needed.
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
This solution reduces the cost and operational load of managing security modules while maintaining the same security level as conventional encrypted GNSS receivers, allowing for secure access control and position calculation without the need for internal security modules.
Implementation Method 1
The processor correlates the internal replica signals with the received signals from the satellites, and uses the results of the correlation process to determine the ranging measurement
Data Source
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AI summary
A device including a communications interface configured to receive encrypted GNSS signals and to receive an assistance message including a replica spreading code, and a processor configured to calculate a position for the device based on the encrypted GNSS signals and the assistance message. The assistance messages may be generated by an external source having the required security module. Methods are also provided for identifying a satellite associated with each observed spreading signal in the event the replica spreading code includes spreading codes from a plurality of satellites.