About sdk14.2 52832 password pairing timeout

[June6]

Hi

I'm working on a password pairing project. You must enter the correct password to connect properly.  And This function can be normally implemented between mobile phone and slave module. When the phone wants to connect, a password pairing box pops up, and you must enter your password to connect properly. But now the password function is also in effect between the master and slave modules. According to the simulation, it is known that the connection is broken because the master module did not respond to the password and the pairing timeout evt is entered from the module. How can i fix this problem?

Thanks

June6

[Einar Thorsrud]

Hi,

Why do you want to exchange the encryption key this way? A more standard way would be to use LE Secure connection to establish the encrypted link in a secure way. Then you could use for instance numeric comparison or pass key entry to provide man-in-the-middle (MITM) protection.

[June6]

Hi,

Can you tell me the standard practice? It's better to attach the code?

Thanks!

[June6]

When the peer is not a phone, but rather a device without a keyboard. It's still work. The master module did not respond to the password. So the slave modules reply BLE_GAP_SEC_STATUS_TIMEOUT. It's not BLE_GAP_SEC_STATUS_SUCCESS. So leading to disconnection.

[June6]

I have set IO capabilities DISPLAY ONLY.  And when is the time to disable MITI?

[June6]

MITM？

[Einar Thorsrud]

What are the IO capabilities on the other side? If that has keyboard capabilities, then you can still use MITM. If not, then MITM is not possible and there will be no passkey used. (In that case characteristics that require MITM will not be accessible.)

This PDF has a nice table that describes the possible combinations of IO capabilities and what MITM protection. Note that you have more capabilities with LE SEcure connections, particularly numeric comparison (in cases where both devices have a display).

[June6]

Both sides are BLE_GAP_IO_CAPS_DISPLAY_YESNO.  However, the slave module will still use MITM and request the master module to respond to passkey. However, I don't know how the central module responds to passkey. And Neither the central module nor the slave module has a display screen. And I experimented on two development boards, one for the central mode and one for the slave mode. Both development boards use the same code. And then I get this problem.

[Einar Thorsrud]

I see. If both sides have BLE_GAP_IO_CAPS_DISPLAY_YESNO then there shall be no MITM (just works) if you use legacy pairing and Numeric comparison if you use LESC. Do you? In any case you should not respond to passkey in this case, just confirm the value. You can refer to the num_comp_reply() function in <SDK 15.2>\examples\ble_central_and_peripheral\experimental\ble_app_multirole_lesc\main.c to see how it can be done.

If that does not help, can you upload your source code for both devices along with some description so that I can look at it?

[June6]

Ok,  This looks like a solution. I'll try. And then I'll tell you the result

Thanks!