"Passive Entry Off/On".....?

"Passive Entry Off/On".....?

Just got a "minor fixes" software update on my Mar '14 S85. I now have an additional button under the Doors/Locks tab called Passive Entry. What is it? What does this Passive entry do that the car didn't already do? BTW at first it was completely grayed out and pre-selected to "On", but once I pressed the brake, it lit up and allowed me to switch it back and forth between off and on.

JPPTM | 2017年9月6日

It disables the automatic walk-up and door unlock with the fob. If Passive Entry disabled, you will need to Actively press on your fob to unlock. Implemented as a precaution due to reports that in some locales (?EU) that crooks with the proper RF receiving hardware and software were able to copy/clone the RF signal from a fob that was communicating passively with a car. Then the crooks could later go up to the same car, unlock it and steal it.

jordanrichard | 2017年9月6日

and this is different how...........? We always had the ability to have the auto unlock on or off. What am I missing.?

Boonedocks | 2017年9月6日

I "think" it means you now have to double click the fob to unlock the car no matter what if enabled. Before with auto unlock off you could walk up and press the handle and it would still present.

I haven't tried it yet but that is my impression of how the new feature works.

BigD0g | 2017年9月6日

@Jordanrichard it prevents the broadcasting between the key and the car, so RFID readers cannot "steal" the signal to replay to the car and open the doors.

BigD0g | 2017年9月6日

+1 boonedocks

jordanrichard | 2017年9月6日

I am at my office, so I only went out to see what the update was about, so I haven't had time to play with this new button, but I am still not seeing what was gained by this. Yes, I get it, with Passive Entry Off, I have to manually press the FOB to unlock the car. Again though, we always had it in the past where you could have auto lock/unlock. So if one selected auto unlock Off, you had to press the FOB. Handles presenting was a separate setting..

rntesla | 2017年9月6日

@jordanrichard This does not add any new functionality as I understand it. This only gives you the option of disabling the functionality you've already had, in case you're worried about theft.

Boonedocks | 2017年9月6日

I guess we will have to wait and see from those that have used it both ways. I thought before even with auto unlock Off you could still press the handle and it would present. The new feature won't allow that. You can press the handle all day long and it will only present if you double click the fob. Again just my understanding from reading...not actual use. lol

BigD0g | 2017年9月6日

My understanding as well boonedocks.

jordanrichard | 2017年9月6日

Boonedocks, ya, auto handles presenting and auto lock/unlock were always 2 separate things. If you chose not to have auto unlock, you walked up to the car, double clicked the FOB to unlock it.

rntesla, the functionality we always had was to disable auto unlock. That's why I don't get what this is all about. I about to leave for a late lunch. I will see what this new thing does.

jordanrichard | 2017年9月6日

Ok, so it is as stated, Off just means you have to double click the FOB to unlock the door. I still don't see anything new about this. The mere fact that we are told in the past that to unlock the car you double clicked the "roof" of the FOB car meant that there was a way to "manually" unlock the car if you didn't have auto (new buzz word Passive) unlock enabled.

Are there any "old timers" that can help perhaps clear up my memory of things and tell me what we are now getting that we didn't have before? After 3 1/2 years of constant changes, perhaps how things were originally in 2014 is not as I think they were.

BigD0g | 2017年9月6日

So, before this, the car was "always" listening for the car to come in range to detect if it should present the handles or not, even if auto present handles was turned off. Now, with this feature enabled it doesn't even listen for the key to come in range, thereby closing the RFID replay attack vulnerability. Note all cars with auto unlock have this vulnerability, it's not Tesla specific, but OTA updates allows Tesla to close this vulnerability if the owner chooses to close it at the cost of convenience for auto presenting handles.

jordanrichard | 2017年9月6日

Well it was "always" listening to detect if it should unlock or not. We have always been able to set the handles to either auto present or not (requiring a slight push) The function of being lock/unlocked was always independent of the handles position. When you get out of the car and then just hang out near the car, the handle(s) after about 30 seconds go back in, but the car is still unlocked. So the position of the handles is independent of the lock status.

BigD0g, I don't really track how long people have been here or if they are owners or not, so please don't take this the wrong way. Are you an owner and for how long?

SomeJoe7777 | 2017年9月6日

As I understand it, the new passive entry setting is controlling the car's low-power broadcasting that is looking for the fob nearby. This is the vulnerability that is being exploited by the criminals. To understand why the passive entry setting was added, you have to understand how the vulnerability works.

With passive entry on, the car is periodically broadcasting a low-power, low-range signal that is looking for the fob. When the fob hears it, the fob responds with a response that the car hears, validates, and then if correct, will unlock the car.

The criminals are exploiting this by using an amplifier and re-broadcaster. The car's low-power/low-range signal is picked up and re-broadcast at high power. Your fob, a long distance away, can hear this signal and it will respond with the correct response that would unlock the car. Normally, that signal wouldn't reach the car, but if it's intercepted it can be played back near the car to successfully unlock it.

The root cause of this problem is the car's periodic broadcasting that looks for the fob. The passive entry setting turns the broadcasting off.

Here's a summary of some various configurations and how the car works under each:

Auto-Present Handles: ON, Auto-Unlock: ON, Passive Entry: ON
In this state, the car is broadcasting looking for the fob at all times (vulnerable). In this state, you walk up to the car, the fob hears the broadcast, responds, the car unlocks and presents the handles.

Auto-Present Handles: OFF, Auto-Unlock: ON, Passive Entry: ON
In this state, the car is broadcasting looking for the fob at all times (vulnerable). In this state, you walk up to the car, the fob hears the broadcast, responds, the car unlocks but does not present the handles.

Auto-Present Handles: OFF, Auto-Unlock: OFF, Passive Entry: ON
In this state, the car is not broadcasting normally (secure). You walk up to the car, press the handle, the car broadcasts looking for the fob (vulnerable), the fob responds, the car unlocks but does not present the handles. This is more secure than the above two setting combinations, but if the response from the fob is captured and recorded, it can be used to re-enter the car later. The handle could be pressed, then the fob response is played back to unlock the car.

Auto-Present Handles: OFF, Auto-Unlock: OFF, Passive Entry: OFF
In this state, the car never broadcasts to look for the fob. In this state, you must double-click the fob and let the fob initiate the unlock sequence. Now there is nothing for the criminals to record or re-broadcast from the car, so they cannot make your fob respond with the unlock sequence.

Please note that this is my best understanding of how things are working with these settings. I may be completely wrong, right, or otherwise. Take it with a grain of salt.

BigD0g | 2017年9月6日

@JordanRichard no worries man, yes i'm an owner 75d, bought in Dec took delivery in early Feb. 2017 and a link to prove my claims, LOL! ->

BigD0g | 2017年9月6日

Awesome post @SomeJoe7777 !! +10

ac838 | 2017年9月24日

Thanks SomeJoe7777

Was completely confused about this feature and you helped clear it up

Solarfan | 2017年9月24日

@SomeJoe7777 +1
Thanks for the complete and clear description!