A GPS receiver device is disclosed comprising a GPS antenna and a GPS RF front-end including an analogue to digital converter for receiving GPS signals and outputting GPS signal samples; and a processor for encrypting the GPS signal samples and transmitting the encrypted GPS signal samples to an external device. Also disclosed is a corresponding method of providing a position fix comprising the steps of connecting to a GPS receiver device and receiving encrypted GPS signal samples therefrom, decrypting the encrypted GPS signal samples and processing the decrypted GPS signal samples to determine a position fix; and a computer program, computer-readable storage medium and apparatus for the same.