Is it possible to change on air address (access address) in BLE advertising

RE: Is it possible to change on air address (access address) in BLE advertising

ovrebekk — Thu, 30 Mar 2017 07:37:23 GMT

I am happy to help :)

As I said I am not sure it is possible to make the phone pick up these packets. You could potentially make a Nordic based bridge, that would connect to the phone over BLE and report on the scanned packets.

RE: Is it possible to change on air address (access address) in BLE advertising

vbachler — Wed, 29 Mar 2017 12:47:03 GMT

Great, I found code for advertising without soft device github.com/.../blessed. Where access address can be modified. Now BLE device is not visible from standard ble scanner app. So now there is a problem how to make it visible from dedicated scanner - which is another issue. Thanks for help.

RE: Is it possible to change on air address (access address) in BLE advertising

ovrebekk — Wed, 29 Mar 2017 09:24:37 GMT

We have source code for doing advertising without the SoftDevice, and in this case you can change the access address. The problem is that there is no API on the phone side to change the access address for BLE advertisements, so you would need a Nordic based scanner device to pick them up (if there were such an API then anyone else would be able to use it also, so maybe this is an advantage).

Then you can change the access address of the advertise packets, and make them invisible to normal BLE scanners.

If you want something that works on ordinary phones then you might have to encrypt the data instead, and keep the standard access address. Then people can see the advertise packets, but will be unable to read the payload content.

Best regards
Torbjørn

RE: Is it possible to change on air address (access address) in BLE advertising

endnode — Wed, 29 Mar 2017 09:13:56 GMT

Access address is fixed for all ADV (and other) packets on channels 37/38/39. What you probably want to change is Adv. address (MAC of the device) and that can be changed freely on Advertiser side as well as filtered on Observer side.

RE: Is it possible to change on air address (access address) in BLE advertising

Wojtek — Wed, 29 Mar 2017 08:49:44 GMT

I am not sure if it will work for multiple scanners, but you should check directed advertising mode then. Or the employees should be peripherals, not the centrals... or just go proprietary.

RE: Is it possible to change on air address (access address) in BLE advertising

vbachler — Wed, 29 Mar 2017 08:47:50 GMT

I would like to distribute beacon like devices among assets/equipment in warehouse. Then employees would have official phones with dedicated ble scanner app which would scan beacons and report their presence. However this beacons shouldn't be visible to "any off the shell ble scanner mobile app"

RE: Is it possible to change on air address (access address) in BLE advertising

Wojtek — Wed, 29 Mar 2017 08:34:57 GMT

Randomizing address would not cause nRF Connect to ignore device. Also setting address that is not compliant with BLE standard (there are some restrictions about some bits afair) would not even cause ignoring the device. Why you want to do such a thing? What is your main goal? Changing device address is easy (sd_ble_gap_addr_set or something), but i don't think it is what you really want.

RE: Is it possible to change on air address (access address) in BLE advertising

vbachler — Wed, 29 Mar 2017 08:31:42 GMT

Idea is to purposely malforme BLE header by changing dedicated access address to random value. Which I hope would cause regular ble scanner software (ex. ble phone app or nRF connect, ...) not to show such device.

RE: Is it possible to change on air address (access address) in BLE advertising

Wojtek — Wed, 29 Mar 2017 08:23:44 GMT

what do you mean by "ignore such advertising"?