Tesla key questions

Hi guys,

I’m Francesco (32) from Italy and together with Amal we founded Novemm, a wearable company we are next to launch in the next weeks.

We focus on Tesla Key wearable product and our first release is the Cybertruck Bracelet.

I’m writing here because I need your help.

At the time one of the very few things we have to do before launching officially the wearable on the market is recording a video showing the Cybertruck Bracelet pairing, locking, unlocking and starting a Tesla vehicle.

Since the fact here in Italy there are not so much Tesla owners to ask for their Tesla vehicles it is easier to rent a Tesla vehicle to record the mentioned video.

Anyway I want to be sure that rented Tesla vehicles can’t have some specific limitations that could prevent to record a video of the Cybertruck Bracelet at work.

In particular I have the following question:

Do all the Tesla key card paired with the same Tesla vehicle as a key can be used to confirm the pairing of a new Tesla key card?

If not does it mean that exists some feature to give to one or more Tesla key cards the role of master keys for a Tesla vehicle (the meaning is the Tesla key cards selected as master keys for one Tesla vehicle are the only to be authorized to pair a new Tesla key card as a key)?

Thanks guys

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In short, nothing happens inside the keycard when you register it for use with a car, so you can use the same keycard with infinity vehicles :slight_smile:

Let me explain, in a very simplified way, how the key card application actually works on the chip. Basically it is a public / private key system that goes through two processes;

  • key registration
  • key authentication

Key registration works by the card giving the vehicle it’s public key. Then the car sends a challenge (random string of data) to the card for signature. The card signs this data with it’s internal private key and sends the signature back to the car. The vehicle validates the signature with the card’s public key it received earlier. If confirmed, the public key is stored in the vehicle as a “registered key”.

Key authentication works basically the same way. A card is presented to the vehicle and the public key is given. If the public key is stored in the vehicle, a new random challenge is sent to the card. The card returns a signature for this challenge and it’s validated be the vehicle using the stored public key. If confirmed, the door opens and you can drive.

Because of the way this works, your card can be registered and used with any Tesla vehicle.

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Thanks Amal, all is clearer now.

Just 1 another question.

Does the Tesla software send a notify (to mobile app or a message to phone number) to the Tesla car owner when a new Tesla key card has been paired?

I ask this because when I explain to rent company what I wanna do they are scared about the fact I could create some issue in their software, so I wanna rent the Tesla without informing about what I wanna do with Cybertruck Bracelet :slight_smile:

I don’t believe so. You do need to use one of the key cards that came with the vehicle originally in order to register a new key card but beyond that I don’t think there’s anything that happens with the management software or anything other than what you do on the screen.

Funny enough I don’t have a Tesla either so I’m not totally sure nothing happens with notifications but I’ve never heard of that happening and it didn’t seem to happen when we filmed our stuff with a friend’s car.

You do need to use one of the key cards that came with the vehicle originally in order to register a new key card.

This was the real point of my question.

Does it means that in case the registered Tesla keycard the rent company give to me is not one of the two that came with the vehicle originally it can’t be used to register new Tesla keycard?

I’m not sure. I think it must be one of the two original key cards… however it might be that any previously registered keycard might work. I’m just not sure.

Can you give Amal a Cyber Truck please


Just be careful that the rented Tesla will let you enrol the key.

I have a BMW and to enrol a digital key card or a phone as key you must have both the original key transponders inside the vehicle at the same time. This is done to stop renters enrolling their own key and being able to steal the vehicle at a later date.

Also BMW have a fleet mode which locks out a lot of the app options (I know this as I just rented one in Germany).

I would be very surprised if Tesla was not across all of this as a major security issue and hasn’t taken steps to prevent it being done by anyone other than the actual owners.

I would be surprised too. I just asked on a Tesla forum if all the registered Tesla key card can be used to confirm the pairing and the answer has been positive.

Now I’m trying to understand if when you pair a new Tesla key card for your vehicle the Tesla software inform you in some way with a notify on mobile app or a message to your phone about the fact a new key has been added.

I Will ask also about a similar feature like the fleet mode.

Thanks for the tips

The Tesla app does notify you when a new key is added, if you are signed in as the owner to the app.


This makes me wonder if a Yubikey could be registered as a Tesla key…

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Nope. The application does not exist on a yubikey.

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I’m a little late to this party but I have a Tesla and have used the key in my Vivokey Apex Flex to register another key to my Tesla. So, adding a new key doesn’t need to be verified with one the original key cards but just another existing key that can be tapped/read by the in-car reader.


To help answer some questions:

  1. There is no notification when a new key has been added to the list of registered keys (to my knowledge), but an interesting feature and one maybe Tesla should implement.

  2. You have to use one of the official Tesla ‘keys’ which originally came with the vehicle, unless you’ve gone to a service center and ‘added’ an additional “parent” key. I know this because I used to work at Tesla and the valet lost my keys twice (no more parent key) - and they had to re-program the keys and add a new one.

  3. If you do not have one of the “parent” keys (either originally came with the vehicle or was added later by service tech) - you cannot register new keys.

@Element5 I’m not sure how that’s possible. That’s not supposed to be possible, unless the Apex is now a “parent” key. The user is not supposed to be able to add a “parent” key.

Hmmm now you’ve made me wonder about this memory. I’ll delete a key and try to add it again with just my Apex to verify it and confirm (or not).

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And as far as I can tell, the rental do not have limitations on adding new keys im in a rental Tesla this week and there were a bunch of extra keys enrolled when I picked it up … And the one marked as “rental company name” cannot be deleted from the system, it’s there but greyed out without a delete icon.

Here are they keys enrolled in the rental with the version #
(The blacked out key is the one with the rental company name)


This is what happens (at least on the car owner’s app) when you add a new key in the car