Authentication based on random bits in satellite navigation messages

1. A method for location authentication, the method comprising:

demodulating a plurality of demodulated client received navigation signals from a plurality of client received satellite navigation signals received at a client device from a plurality of navigation satellites respectively;

selecting a subset of the demodulated client received navigation signals to provide a plurality of client bit frames;

computing a function of the client bit frames to provide a client signature set;

selecting a subset of a plurality of demodulated server received navigation signals synchronized to the client bit frames to provide a plurality of synchronized server bit frames;

computing the function of the synchronized server bit frames to provide a server signature set;

comparing the client signature set and the server signature set to provide a comparison result; and

authenticating a location of the client device based on the comparison result.

2. The method of claim 1 , wherein the function comprises one of: a logical XOR function, a logical OR function, and a logical AND function.

3. The method of claim 1 , wherein demodulating the demodulated client received navigation signals from the client received satellite navigation signals comprises:

conversion from RF to baseband;

band pass filtering; and

analog to digital conversion.

4. The method of claim 3 , wherein demodulating the demodulated client received navigation signals from the client received satellite navigation signals further comprises:

code wipe-off; and

carrier wipe-off.

5. The method of claim 3 , wherein the authenticating step further comprises:

sending a test waveform from a server device to the client device;

comparing the test waveform at the client device with the demodulated client received navigation signals at the client device to provide correlation information; and

sending the correlation information back to the server device to provide an authentication decision message.

6. The method of claim 1 , further comprising receiving the client received satellite navigation signals at the client device.

7. The method of claim 1 , further comprising demodulating the demodulated server received navigation signals from a plurality of server received satellite navigation signals received at a server antenna from the navigation satellites respectively.

8. The method of claim 7 , further comprising receiving the server received satellite navigation signals at the server antenna.

9. The method of claim 7 , wherein demodulating the demodulated server received navigation signals from the satellite navigation signals comprises:

conversion from RF to baseband;

band pass filtering;

analog to digital conversion;

code wipe-off; and

carrier wipe-off.

10. The method of claim 1 , wherein the subset comprises one of: a subframe, a random selection, and a selection of bits from most dynamic bits.

11. A location authentication system comprising:

a client demodulation module operable to:

receive a plurality of client received satellite navigation signals at a client device from a plurality of navigation satellites respectively; and

demodulate a plurality of demodulated client received navigation signals from the client received satellite navigation signals;

a client data frame selector module operable to select a subset of the demodulated client received navigation signals to provide a plurality of client bit frames;

a client data operation module operable to compute a function of the client bit frames to provide a client signature set;

a server data frame selector module operable to select a subset of a plurality of demodulated server received navigation signals synchronized to the client bit frames to provide a plurality of synchronized server bit frames;

a server data operation module operable to compute the function of the synchronized server bit frames to provide a server signature set;

a server correlation module operable to compare the client signature set and the server signature set to provide a comparison result; and

an authenticate module operable to authenticate a location of the client device based on the comparison result.

12. The system of claim 11 , wherein the client demodulation module is further operable to:

perform conversion from RF to baseband;

band pass filtering; and

perform analog to digital conversion.

13. The system of claim 11 , wherein the client demodulation module is further operable to:

perform code wipe-off; and

perform carrier wipe-off.

14. The system of claim 11 , further comprising a server demodulation module operable to:

receive a plurality of server received satellite navigation signals at a server device from the navigation satellites respectively; and

demodulate the demodulated server received navigation signals from the server received satellite navigation signals.

15. The system of claim 14 , wherein the server demodulation module is further operable to:

perform conversion from RF to baseband;

band pass filtering;

perform analog to digital conversion;

perform code wipe-off; and

perform carrier wipe-off.

16. A location authentication system comprising:

a client data frame selector module operable to select a subset of a plurality of demodulated client received navigation signals to provide a plurality of client bit frames;

a client data operation module operable to compute a function of the client bit frames to provide a client signature set;

a server demodulation module operable to:

receive a plurality of server received satellite navigation signals at a server device from the navigation satellites respectively; and

demodulate a plurality of demodulated server received navigation signals from the server received satellite navigation signals;

a server data frame selector module operable to select a subset of the demodulated server received navigation signals synchronized to the client bit frames to provide a plurality of synchronized server bit frames;

a server data operation module operable to compute the function of the synchronized server bit frames to provide a server signature set;

a server correlation module operable to compare the client signature set and the server signature set to provide a comparison result; and

an authenticate module operable to authenticate a location of a client device based on the comparison result.

17. The system of claim 16 , wherein the server demodulation module is further operable to:

perform conversion from RF to baseband;

band pass filtering;

perform analog to digital conversion;

perform code wipe-off; and

perform carrier wipe-off.