[Interest] BLE : Bonding and ble security
Simon FEUTRIER
sfeutrier at bluegriot.com
Mon Aug 17 17:17:45 CEST 2020
Alex, I can discover all services and characteristics, without any errors.
I have the same behavior with the example project "lowEnergyScanner". Using
connectToDevice is OK.
Question, is Qt able to communicate in security mode with an Unknown
Service ? Because the service I'm using is particular.
I'm not able to read or write in this service. Meanwhile I am able to read
the characteristic's value of services Generic Access, Generic Attribute
and Device Information.
Jérôme, when talking about bonding I mean bonding :p. I just saw with the
nrf connect app that the app cannot read until bonding is done in Just Work
mode. So I guessed that in this security bonding is mandatory. That is the
only difference between working exchange and not working exchange.
Cordialement,
Simon Feutrier - Ingénieur systèmes embarqués
BLUEGRioT
Le lun. 17 août 2020 à 17:06, Jérôme Godbout <godboutj at amotus.ca> a écrit :
> As for the bounding (take care of the wording, in BLE many people confuse
> them):
>
> Terminology
>
> *Term*
>
> *Info*
>
> Connection
>
> Act of establishing a link between 2 device, this create an anonymous
> connection. This is a mandatory step into communicating with a device
> beyond the advertising.
>
> Pairing
>
> Act of exchanging the security and encryption key once authentication is
> completed.
>
> Bonding
>
> Act of keeping the pairing key into NV memory for next time the pairing is
> requested to avoid the authentication and pairing steps.
>
> Authentication
>
> Act to validate the device with each other. This require the connection to
> be done. There is several way to authenticate: pin, OOB, etc...
>
>
>
> As for the authentication, it depends on the flags allowed by both devices
> (OOB is not part of this table and Just Work is always the fallback):
>
>
>
> Also the security level requested by both end:
> *LE Security*
>
> *Mode*
>
> *Level*
>
> *Name*
>
> *Bluetooth version*
>
> 1
>
> 1
>
> No Security (no authentication and no encryption)
>
> All
>
> 2
>
> Unauthenticated with encryption
>
> >= 4.0
>
> 3
>
> Authenticated with encryption
>
> >= 4.0
>
> 4
>
> Authenticated LE Secure Connections with 128 bits encryption
>
> >= 4.2
>
> 2
>
> 1
>
> Unauthenticated with data signing
>
> >= 4.0
>
> 2
>
> Authenticated with data signing
>
> >= 4.0
>
>
>
> After your are connected to a device, the authentication process should be
> started be the central. The end device might request the procedure to be
> started. Make sure the right flags are set to the connection capabilities.
> Also make sure the documentation allow the API for Windows, I know that Qt
> Windows API was having limitation but should now work, maybe some part of
> it ain’t cover just yet.
>
>
>
>
>
> *From:* Interest <interest-bounces at qt-project.org> *On Behalf Of *Jérôme
> Godbout
> *Sent:* August 17, 2020 10:50 AM
> *To:* Simon FEUTRIER <sfeutrier at bluegriot.com>
> *Cc:* interest at qt-project.org
> *Subject:* Re: [Interest] BLE : Bonding and ble security
>
>
>
> Can you discover the service and the characteristics? are there any errors
> while doing so? Make sure to discover those before writing to them, might
> help to see if anything went wrong.
>
>
>
> *From:* Simon FEUTRIER <sfeutrier at bluegriot.com>
> *Sent:* August 17, 2020 10:32 AM
> *To:* Jérôme Godbout <godboutj at amotus.ca>
> *Cc:* interest at qt-project.org
> *Subject:* Re: [Interest] BLE : Bonding and ble security
>
>
>
> Alex, thank you for your quick reply. I just tried with the pre-release
> 5.15.1 and this is the same behavior.
>
> When trying to activate notification (first write to characteristic that I
> do), it always fails to write. Qt still never initiates the bonding.
>
> Could you clearly tell me if it is supposed to work or if this has not
> been implemented yet ?
>
>
>
> Jérôme, thank you for your message, sorry I forgot to specify I am working
> with Windows 10 with MSVC. I'm sure your message will be helpful but I
> don't think it applies to my case.
>
>
>
> Best regards,
>
>
>
> Simon Feutrier
>
>
>
>
>
> Le lun. 17 août 2020 à 15:52, Jérôme Godbout <godboutj at amotus.ca> a
> écrit :
>
> Here is my error code I’m currently using:
>
>
>
> switch (error)
>
> {
>
> case QLowEnergyController::Error::AdvertisingError:
>
> case QLowEnergyController::Error::UnknownRemoteDeviceError:
>
> case QLowEnergyController::Error::UnknownError:
>
> case QLowEnergyController::Error::InvalidBluetoothAdapterError:
>
> case QLowEnergyController::Error::NetworkError:
>
> case QLowEnergyController::Error::ConnectionError:
>
> #if QT_VERSION >= QT_VERSION_CHECK(5, 10, 0)
>
> case QLowEnergyController::Error::RemoteHostClosedError:
>
> #endif
>
> #if QT_VERSION >= QT_VERSION_CHECK(5, 14, 0)
>
> case QLowEnergyController::Error::AuthorizationError:
>
> #endif
>
> break;
>
> // Code 0x22 (0d34) seem to be link to unsupported Read
> Characteristic on device the read timeout, missing read/write connect on
> service?
>
> // Android problem: BLE_HCI_STATUS_CODE_LMP_RESPONSE_TIMEOUT
>
> case 0x22:
>
> qDebug() << "Android Device have problem
> BLE_HCI_STATUS_CODE_LMP_RESPONSE_TIMEOUT or GATT CONN LMP TIMEOUT: " <<
> error;
>
> // TODO godboutj 2018-06-11, find a fix or a workaround this
> issue
>
> break;
>
> // Special erro 129 QLowEnergyController Error is Generic Android
> internal error. Often just disconnecting and reconnecting help the issue
>
> case 0x81: // (0d129)
>
> qDebug() << "Android generic error, disconnect and try to
> reconnect again";
>
> break;
>
> // Special erro 133 GATT_ERROR, seen on Samsung Android 8 tablet,
> reason can be almost anything
>
> case 0x85: // (0d133)
>
> qDebug() << "Android device error, not sure about why we get
> this on some device";
>
> break;
>
> // More code explaination can be found here:
> http://allmydroids.blogspot.com/2015/06/android-ble-error-status-codes-explained.html
>
> default:
>
> qDebug() << "UnhandledError: " << error;
>
> break;
>
> }
>
>
>
> If that might help others developing with Android. This will generate some
> warning for bad enum value, but they are showing up on Android… If someone
> have information about those error, I will gladly be accepting any
> information about why they can occur.
>
>
>
>
>
> *From:* Interest <interest-bounces at qt-project.org> *On Behalf Of *Jérôme
> Godbout
> *Sent:* August 17, 2020 9:25 AM
> *To:* Simon FEUTRIER <sfeutrier at bluegriot.com>; interest at qt-project.org
> *Subject:* Re: [Interest] BLE : Bonding and ble security
>
>
>
> Hi,
>
> If you are using Qt and Android for the application. I did found over time
> to have a reliable behavior with Android connection step, you kind of need
> to slow things down on Android platform (this doesn’t apply to Windows,
> Mac, iOS). I delayed my task by 500 ms after connecting and doing anything
> (services discovery, pairing, authenticate… under Android. Also do this
> when I disconnect (garbage collector issue?!) and avoid reconnecting too
> quickly. This have solve many problems I had under Android. Android
> Bluetooth LE stack is really bad before Android 8. If you can, try to make
> things work with a recent device and Android 8+, then patch the behavior
> for older device if you can.
>
>
>
> I also found that a few manufacturer have more issue (but this might just
> be a specific product, I don’t have enough data to make sure this is
> happening all the time):
>
> - Google Nexus 7", Android 6.0.1 can raise undocumented Error 34
> (0x22) GATT CONN LMP TIMEOUT
> - LG K4 LTE, Android 5.1.1 Debugger doesn’t run too well
> - Lenovo (cheap tablet, I don’t remember the actual model #) the
> advertising is a big mess (some low level filtering, making beacon
> continuous discovery impossible).
> - Samsung many older version had some debugger issue (missing or
> renamed tools)
>
>
>
> If you Android BLE start behaving heraldically, turn off the BLE and wait
> at least 20s before activating again. Seem like the garbage collector/clean
> up task is fairly slow.
>
>
>
> Hope this might help you.
>
> Jerome
>
>
>
>
> une compagnie
>
> RAPPROCHEZ LA DISTANCE
>
> *Jérôme Godbout*
> Développeur Logiciel Sénior /
> Senior Software Developer
>
> *p:* +1 (418) 800-1073 ext.:109
>
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>
> *From:* Interest <interest-bounces at qt-project.org> *On Behalf Of *Simon
> FEUTRIER
> *Sent:* August 17, 2020 3:48 AM
> *To:* interest at qt-project.org
> *Subject:* [Interest] BLE : Bonding and ble security
>
>
>
> Hi,
>
>
>
> That is the first time I use this mailing list, so tell me if I'm doing
> anything wrong when using it. Thanks !
>
>
>
> Now my problem.
>
> I'm developing a Qt application that communicates with a BLE device. It
> worked perfectly until I tried to add some security. When I turned on "Just
> Works" security mode (device side), I was not able anymore to write in a
> characteristic (or read) from my Qt application.
>
> I compared the Bluetooth messages sent from Qt app and from the android
> app *nfr Connect* and I see that automatically, the *nrf Connect* app
> sends a bonding request when it fails to write.
> Qt does not do this. That is the only difference that makes the android
> app working but not my Qt app.
>
>
>
> I finally made it work once : I start my Qt App, pair my BLE device with *Windows
> parameters* and then it works *one time *only (after that I need to
> unpair my device from Windows parameters and redo the same process). It
> only works if it has been paired with Windows parameters...
>
> I could not find anything about bonding in the API or security mode
> settings.
> Any idea ? Should I post it as a bug or am I missing something ?
>
>
>
> Thanks,
>
>
>
> Regards,
>
>
>
> Simon Feutrier
>
>
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