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Session D6: Application/Impact of PNT Technologies in the Homeland Critical Infrastructure

Out-of-Band (OOB) GPS Navigation Message Authentication (NMA)
Michael H. Cole, Ranwa Haddad and Karl L. Kovach, The Aerospace Corporation
Location: Ballroom B
Date/Time: Thursday, Aug. 26, 9:15 a.m.

The Global Positioning System (GPS) provides Position, Navigation, and Timing (PNT) services to critical infrastructure services across public and private sectors through its Standard Positioning Service (SPS). U.S. federal policy, including Memorandum on Space Policy Directive 7 issued on 15 January 2021, directs the pursuit of a “strategy and future requirements to implement GPS data and signal authentication,” as well as adoption of resilient PNT solutions within critical infrastructure. This presentation summarizes the technical and programmatic feasibility of augmenting the GPS SPS services with an out-of-band (OOB), Internet Protocol network-based public service to provide cryptographically authenticated GPS constellation navigation message data products to networked civilian GPS receivers. Compatible GPS receivers (mobile phones, surveying equipment, etc.) would integrate these data products with ranging and message information within the observed signals in space. OOB navigation message authentication (NMA) would enable networked SPS receivers to detect and reject received L-band navigation signals containing modified or forged satellite ephemeris or state information. Additionally, OOB NMA information could be published more frequently than GPS satellites are updated, translating into improved GPS user accuracy for compatible receivers. This OOB NMA service could be implemented prior to the incorporation of authentication services within GPS SPS signals in space. This presentation proposes a candidate collection of legacy and modernized civilian navigation message data fields that would be included in OOB NMA data products, identifies programmatic risks to be retired, and concludes that the approach is feasible if the U.S. federal government chose to pursue this GPS enhancement.

Approved for Public Release. OTR 2021-00347



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