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Session A1: Space and Satellite Applications, NTS-3 Overview

Profiling Embedded Performance of Generating Chimera Authentication
Jared Kresge, Samuel Wamsley, Glen Giffey, CAL; Sanjeev Ganawardena, AFIT
Date/Time: Tuesday, Aug. 24, 2:50 p.m.

The experimental Navigation Technology Satellite 3 (NTS-3) is expected to transmit messages which implement Chips Message Robust Authentication (Chimera). Chimera provides authentication for the message data content and the signal spreading code by cryptographically generating punctures. These authentication features enable detection and mitigation of spoofing attempts on the L1C GPS signal. In order to evaluate Chimera for the NTS-3 software defined radio (SDR) testbed, the generation of Chimera authentication outputs were added to the RV funded GNSS Waveform Prototyping Platform (GWPP) project.
Over the last year, an L1C signal symbol generation library has been in development to support NTS-3 benchtop testing. Implemented in C++17, it has been verified operational by comparing the generated symbols against a known good decoder implementation. Recently the Chimera authentication algorithm has been added which provides both navigation message authentication (NMA) symbol output and spreading code authentication (SCA) puncture output. The Chimera cryptographic functions have been built using the open-source OpenSSL library.
The target platform for GWPP, including the Chimera L1C authentication, is an SDR with embedded ARM processor. Therefore, measuring the processor load created by the Chimera authentication algorithm is an important analysis to perform to figure out any potential memory or computational load issues.
In this presentation, a brief introduction to the Chimera authentication will be provided. Next, the software implementation of the Chimera symbol and puncture generation will be presented. Finally, the profiling results of generating the Chimera authentication outputs will be discussed.



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