GPS already has an encrypted channel. It's a severe pain in the ass to work with computationally, so nobody does. Even the military. It used to be that the c

GPS already has an encrypted channel. It's a severe pain in the ass to work with computationally, so nobody does. Even the military. It used to be that the clear channel was less accurate (even beyond the 'selective availability'), but signal theory got us to cm granularity without the computational expense of the military channel.