51–60 of 449 posts
Earlier quoted context omitted.
I think that assumes that all the processing the key fob does internally is reliable constant-time down to the nanosecond. I don't know if that's true but my first guess is that it's doubtful.
Well, those chips are designed for this one purpose and nothing else - it should be possible to design them in such a way that the encryption/decryption process always ends in constant time.
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> it should be absolutely trivial to detect how far away the key is based on the response time Is that true? Accurate, very low power distance detection has a lot of potential applications (e.g. your phone straying too far away) but BLE (for example) doesn't really work for measuring distance--through signal strength--at all. If it's possible, I'd be very curious how to build such a distance detector.
I think the timing method relies on a challenge response. In short, one side sends something and the other side expects a reply within some amount of time. If you just simply add distance to the system with no additional overhead. The time it takes for the ack should go up in a measurable amount of time. And if you did anything more -- like some of the system do today -- where they make a generic pipe that pipes it o…
[1] https://locatify.com/blog/in-practice-precise-indoor-locatio...
It seems car manufacturers are eager to be "cool" but not thinking about the consequences of their actions Center "touchscreen" consoles with awful usability, shifters that are not obvious (coupled with people that are too lazy to pull the parking brake) and now this
Voice can be sort of ok, as long as your speech models are locally stored (no internet blackspots), but deny access to those who cannot talk, or for whom you haven't bothered to build a speech model that matches their language/accent.
I already put mine in a metalic bag for the night, or just press the "lock" button twice which disables the keyless entry system entirely. Manufacturers really need to hurry up and implement more accurate timing detection in the keys - it should be absolutely trivial to detect how far away the key is based on the response time, but for some reason manufacturers don't do this yet. Edit: I also know people who take the…
« it should be absolutely trivial to detect how far away the key is based on the response time » It's not possible. A keyfob has a relatively slow R/F communication channel, less than 1 Mbit/s (at best) because it's constrained by power. Thus the "length" of a bit transmitted over the air is 300 meters or more. The receiver needs to demodulate "300 meters" of R/F signal to recover a single bit. A difference of +/- 10…
What a coincidence.
Jokes aside, this is bound to happen.
It’s disturbing that a vulnerability like this isn’t caught as a show-stopper before the technology is sold to consumers.
I'm confused. Are there cars where the fob can automatically start the car, without any button presses, just from proximity? How did they not realize that was a bad idea?
The car manufacturers are going to need to incorporate a time of flight measurement into the key system. Obviously amplitude can be faked.
So the test for amplitude is aided by the fact that the signal strength received at the car increases by a factor of four if the distance is cut in half. Thus, you have a nice margin for setting your threshold. With measuring the time, however, presuming that radio signal will travel on the order of one foot per nanosecond, you have much less of a threshold tolerance. If the unlock takes place within two feet of the…
Earlier quoted context omitted.
« it should be absolutely trivial to detect how far away the key is based on the response time » It's not possible. A keyfob has a relatively slow R/F communication channel, less than 1 Mbit/s (at best) because it's constrained by power. Thus the "length" of a bit transmitted over the air is 300 meters or more. The receiver needs to demodulate "300 meters" of R/F signal to recover a single bit. A difference of +/- 10…
Is there any reason that keyfobs couldn't use 2.4 GHz (aside from cost)? Apple claims to be detecting if your Apple Watch is close enough to unlock your computer using Bluetooth at that frequency. Bluetooth LE also seems to claim battery life that is competitive.
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Is there any reason that keyfobs couldn't use 2.4 GHz (aside from cost)? Apple claims to be detecting if your Apple Watch is close enough to unlock your computer using Bluetooth at that frequency. Bluetooth LE also seems to claim battery life that is competitive.
BLE beacons do a crap job of detecting distance and battery life is just OK (a few months typically). BLE can obviously be used to differentiate between in-range and out-of-range which is useful for some applications but you can't really use it to measure distance more granularly.
I'm just trying to think of any reason the keyfobs NEED to use low frequencies, and all I can come up with is cost
Nothing new, has been going on for a while now. Market is already providing your own "cage of Faraday[0]" for your fob. [0] https://www.amazon.com/faraday-cage-key-fob/s?page=1&rh=i%3A...
Since most car manufacturers seem to be vulnerable (to my knowledge), I assume all or most buy the same COTS keyfob + electronic lock product. Much like Takata airbags or Bosch ECUs. Being a step away from the problem probably helps keep that OEM manufacturer from strapping in and solving it. They don't feel any pain from it.