[jevinskie]

I found an interesting slide deck that talks a bit about spoofing and key management. [0] Apparently there are different levels of classification for keys. (pg 23) But they must be derived keys, right? The satellites are only broadcasting one signal, not multiple signals each keyed to one receiver. I think there can only be one possible cipherstream (and thus one key) in the very low bandwidth signal.

[0] http://www.ko4bb.com/Manuals/05)_GPS_Timing/GPS_-_SAASM_brfg...