I discussed this with my friend yesterday and wondered about key management with the military GPS channels. Is there a single key that, if extracted* from just

I discussed this with my friend yesterday and wondered about key management with the military GPS channels. Is there a single key that, if extracted* from just one military GPS receiver, could spoof all military signals? Or are there multiple keys, possibly with a revocation scheme? GPS is getting old, what was the state of the art key management back then? * I'm sure the anti-tamper technology is pretty great.