[michaelt]

TLDR: no.

GPS spoofing can be done as a replay attack; record the signal at the airport, rebroadcast at the Kremlin louder than the direct satellite signal and voilà, your receiver says you’re at the airport.

As it’s just a replay attack of the original signal, encryption can’t help.

[woodruffw]

> As it’s just a replay attack of the original signal, encryption can’t help.

Couldn't this be mitigated by added a nonce or using CBC within the cryptosystem? Replay attacks are well understood; I'd be surprised if any (eventual) proposal for signed/encrypted GPS didn't include something to defend against them.

[jhayward]

As I loosely explained in another comment, you essentially never see repeats. The replay happens at the speed of light, and time stamps are broadcast once every 6 seconds at 50 BPS.

The receiver sees the rebroadcast because it captures the receiver's RF chain by being the strongest signal.