An apparatus and method are described for processing a global navigation satellite system (GNSS) signal, the GNSS comprising multiple satellites, wherein each satellite transmits a respective navigation signal containing a spreading code. The method comprises receiving an incoming signal at a receiver, wherein the incoming signal may contain navigation signals from one or more satellites; encrypting the incoming signal at the receiver using a homomorphic encryption scheme to form an encrypted signal; and transmitting the encrypted signal from the receiver to a remote server.