[Replicant] Exposure Notification not working

[doak]

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
manner.
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


Reagrds,
doak



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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