New random static bluetooth address after every boot with Matter

RE: New random static bluetooth address after every boot with Matter

BertL — Thu, 04 Jan 2024 13:39:28 GMT

Our product is not wearable and it will stay at the same location, so tracking is not an issue in this scenario. We will investigate the possibilities, thanks for your answers!

RE: New random static bluetooth address after every boot with Matter

Hung Bui — Thu, 04 Jan 2024 13:27:49 GMT

I think it is a problem. If you advertise the device with an unique number that doesn't change over time it's very easy to track the device with any Bluetooth scanner. Imagine a customer buy a wearable device and carry it, the customer can be easily tracked if the data in the advertising packet doesn't change over time.

This is just my opinion, I would suggest you to double check it with CSA , the organization that watching over Matter. There will be some requirements you need to pass to be able to pass their certification.

RE: New random static bluetooth address after every boot with Matter

BertL — Thu, 04 Jan 2024 12:58:35 GMT

Thanks, that's clear. In our case a changed device address would not add a lot of privacy as we always advertise a device id in the manufacturer data. So that can be used to track a device even though the address is changed. Would this be a problem according to the Matter spec?

RE: New random static bluetooth address after every boot with Matter

Hung Bui — Thu, 04 Jan 2024 12:51:53 GMT

Hi BertL,

It's enforced by the spec because of privacy reason. If you take a look at the Matter Specification at section 5.4.2.5.5 you can find this:

5.4.2.5.5. Advertising Address
To ensure privacy, commissionable devices SHALL use LE Random Device Address (see Bluetooth®
Core Specification 4.2 Vol 6, Part B, Section 1.3.2.1 "Static device address") for BLE Advertising and
SHALL change it at least on every boot.

It's a mandatory requirement.

If you want to recognize the device even after it reboots you would need to bond with it and get the IRK key so that you can resolve the random address that it generate after each reboot.