4 ms·
Why aren’t GPS signals digitally signed? It would be simple to prevent this kind of attack.
by jrue 9y ago
Why aren’t GPS signals digitally signed? It would be simple to prevent this kind of attack.
- Isamu 9y agoWhy would the US military create a system it couldn't manipulate itself? GPS is operated and maintained by the USAF. https://www.gps.gov https://www.gps.gov
- mitchty 9y agoThey are. https://en.wikipedia.org/wiki/GPS_signals#Precision_code https://en.wikipedia.org/wiki/GPS_signals#Precision_code
- gbacon 9y agohttps://en.wikipedia.org/wiki/GPS_Block_IIIA#Military_(M-code) https://en.wikipedia.org/wiki/GPS_Block_IIIA#Military_(M-cod...
- tropo 9y agoFor this, the attack is from the operator of the GPS signals. There is no defense; the attacker could digitally sign the signals or even shut off the satellite. For an attack in a foreign country, digital signatures only prevent false information. A digital signature does you no good if the interfering signal is far stronger than the desired signal. The desired signal may even go missing if the enemy attacks the satellite. Military users can choose to use encrypted GPS signals. This at least lets them know to ignore an attacker, but doesn't help with hearing the legit signal. Military users sometimes use highly directional antennas to avoid picking up jammers near the ground, but that is no help against an enemy that can put a jammer in their own satellite.
- hedora 9y agoEncryption probably doesn’t solve the replay attack problem here. If you can jam + retransmit the signals from the satellite with a sufficiently small delay, then you can change the position the receiver computes.
- tritium 9y agoJamming is denial of service. If the transmission medium is flooded with a high noise floor, digital signal processors will fail to decode any valid values from the band the carrier signal transmits on. Authentic signatures have no utility if excessive noise outshines the entirety of the signal. No one can check any signatures, if the signed message cannot reach an audience. Perhaps an aperture could prevent omni-directional cross-talk and interference, forcing a receiver to only listen from a specific, selected line-of-sight source, but to simulate warfare, what if the enemy really does manage to completely destroy a resource? A genuine disruption keeps everyone honest in the spirit of the exercise. It’s really down. Not just “what if”? No peeking. No cheating.
- jrue 9y agoI see. So it’s not just about spoofing messages.
- Nokinside 9y agoCryptography (P-code or M-code) protects against spoofing not against straight forward jamming. 10-watt jammer can deny large area from military ans civilian signals. You need more advanced antennas and other methods to protect against jamming. These multi-element controlled-reception pattern antennas are larger and more expensive.
- knowaveragejoe 9y ago"Attack" implies something that I don't think is going on here. They developed the system and have full control over it. This is like saying if Google were to stop serving a certain locale for a certain period of time that they were attacking their own service.
- chiph 9y agoIt's still a relatively weak radio signal, and that can be jammed analog-style.