Micaela Troglia Gamba, Mario Nicola, Beatrice Motella, LINKS Foundation, Italy

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Chimera is a signal authentication enhancement suitable to protect the L1C GPS signal. As specified by the acronym itself, that stands for Chips-Message Robust Authentication, it is based on the insertion of authentication features both at the message and spreading code levels. The data in fact are digitally signed, while the spreading code is protected by the insertion of cryptographically generated punctures. The Chimera interface specification document has been made public in 2019, while its first transmission is expected to be broadcast from the Navigation Technology Satellite 3 (NTS-3) satellite. This paper describes the software implementation of the functions required to enable a GNSS software receiver to elaborate the Chimera authentication service. It includes the description of the development work and the detailed software profiling analysis, thus allowing for the evaluation of the additional computational burden required by the Chimera verification, useful to provide important guidelines for the receiver implementation.