Non Bluetooth/BLE Keyfob implementation

[Deepak Gupta]

Hello

I have a use case of typical 3 key (lock / unlock / alarm) car remote lock key fob implementation. Since I already have nRF82810 / 840 based hardware designs that can do this I wanted to check if there is any supporting firmware for this.  

However, I dont want the communication / traffic to be visible to mobile or similar Bluetooth/BLE capable devices. Is this possible? We can use the 810 on the car side and a 810/840 on the key fob. 

TIA. 

[Edvin]

Hello,

This depends on what you mean by "invisible" communication. All packets are on air, so it is not possible to hide them completely. However, most devices are ignored by the OS on phones, unless they contain a standard BLE service that the phone find useful, such as a keyboard/mouse or other HID devices.

So if you use a custom service, that would in one way be invisible for other users. However, if you have a BLE app, such as nRF Connect for iOS or Android, you will be able to see all BLE devices that are advertising.

I would of course recommend to enter a connection in order to use buttons on the keyfob. This is because then you can use encryption when you press the open/lock/alarm buttons, which makes them impossible to record, and use replay attacks to unlock the car.

Best regards,

Edvin

[Deepak Gupta]

Hi Edvin,

Thanks for that. Let me clarify, I dont want the keyfob as to show up as a BLE/Bluetooth device, even when scanned by nRF connect. If this possible. 

[Edvin]

No. All devices are visible if someone is scanning for them. It is not possible to hide from that.

Now, I don't remember if you use directed advertising, that it is filtered out by the OS on the phone, so that you can't see it in nRF Connect for iOS/Android. But you are able to see it using e.g. nRF Connect for Desktop, or a BLE sniffer. 

Because the packets are on the air, it is simply impossible to hide it 100%.

BR,

Edvin

[Deepak Gupta]

Directed advertising should be good enough for my requirement. Thanks Edvin.