SNAP: An authentication concept for the Galileo open service

The design of a solution for the authentication of both navigation data bits and spreading code chips, referred to as SNAP and suitable for the evolution of the Galileo E1 OS signal, is presented in the paper. Though the technique is innovative and able to achieve predefined authentication performance, it exploits the structure of the legacy Galileo signal and the characteristics of the OS NMA. A detailed overview of the open choices for the design of signal components dedicated to authentication is provided, together with an analysis of signal parameters definition. A possible implementation option of the SNAP solution is also presented.