[Replicant] Exposure Notification not working

doak+list at posteo.net doak+list at posteo.net
Fri Feb 5 20:51:09 UTC 2021

Hi Nick, hi all,

I tried the bluetooth firmware from an i9300 Lineage 16.0 which worked with CCTG, but it did not succeed.
The app tries to get location permissions which does not work, i.e. the system config does not recognise this app needing it.
So it seems the Android permissons stack does not support the way the app requests it. In fact I do not believe that the firmware is even involed at that point.

Does anybody here know more about permissions API stuff? I thought the official german Corona app (CWA) as well as it fork using MicroG (CCTG) does support Android 6 (but I can be wrong). Is there anything special in this regard for Replicant 6.


On 8 January 2021 00:31:56 CET, doak <doak+list at posteo.net> wrote:
>Hi Nick,
>there is some news about it:
>I have found a custom Lineage ROM which supports BLE peripheal mode (beacons) for i9300 and it seems to work
>like a charm with and CCTG [1] which includes 'microG'.
>Both, Replicant 6 and these ROMs use Linux 3.0.101, hence it seems to be possible to create a patch for the
>Bluetooth stack and perhaps use another firmware to get that working with Replicant in a free software compatible
>Let me know what you think.
>> Are you able to compare whether the
>> firmware in your working i9305 is the same as the one that you would
>> have used with replicant, [...]
>Sorry for leaving this unanswered. I am trying to have a look into this the next days ^^
>[1] https://codeberg.org/corona-contact-tracing-germany/cwa-android
>On 20.10.20 14:25, Nick wrote:
>> Hi doak,
>> Thanks very much for your response, your questions are things that I
>> hadn't generally thought of!
>>> Did you check if your device actually sends BLE beacons?
>> I did not! I checked that it received beacons, and it does, so I
>> naively assumed therefore that all would be perfect.
>>> At the beginning of the german tracing app I configured an i9305 (S3 LTE) with Lineage, OpenGApps and the
>>> app (this not free SW) and *it seemed* to work but did **not**!
>>> Reason was that BLE beacons could be received, but not sended. I checked that with 'nRF Connect' which is
>>> able to trace bluetooth packets and shows additional information also for BLE beacons. Furthermore it is
>>> able to list device capabilities. In my case 'Periphal mode' was not availabble.
>>> At the end I have tried dozen different (questionable) ROMs till I found one which in fact supports pheriphal
>>> mode and thus was able to send BLE beacons.
>> I found an apk for the proprietary 'nRF Connect' app
>> (no.nordicsemi.android.mcp) online and installed it. It does indeed
>> list 'Peripheral mode' as not supported on this device (basic
>> Bluetooth Low Energy is, though). I only have one other android
>> device, which has very old software on, and I couldn't get nRF
>> Connect to install, so I couldn't test whether my phone was indeed
>> successfully sending BLE beacons, but presumably not. There is more
>> information about this "peripheral mode" being essential to the
>> sending aspect of exposure notifications at [0].
>> There is still some utility in running the app in "receive only"
>> mode, as I would still be alerted if someone I was in contact with
>> sufficiently closely tested positive and could have been infectious
>> at the time. But obviously it's nicer to be able to return the
>> favour.
>>> I am still not sure if the signal strength is as strong as it should be. My gut feeling is that it is too
>>> weak which would make the estimated risk wrong and thus useless.
>> I have no idea how one could test such a thing. It does seem to be
>> collecting lots of IDs when I've been out, more than I would expect
>> if it was weaker than it should be. But I have no way of knowing
>> either.
>>> Furthermore I at least know that the i9305 is able to send them if used kernel/firmware supports it. Dunni
>>> about i9300.
>> That is interesting indeed. I wonder what would be required of
>> replicant to support it. Are you able to compare whether the
>> firmware in your working i9305 is the same as the one that you would
>> have used with replicant, presumably that listed in
>> i9305-fwinfo/bluetooth.txt from
>> https://code.fossencdi.org/firmwares_nonfree.git ? If it is the
>> same, then at least we know that it's likely to be a kernel, rather
>> than firmware, issue. And if not, then potentially finding some
>> newer firmware could be enough to fix it.
>> Thanks again,
>> Nick
>> 0: https://github.com/corona-warn-app/cwa-app-android/issues/688
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