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!

[Einar Thorsrud]

Hi,

I think I misunderstood the posts when I read them initially. Can you elaborate what you want to do? Is the problem that you use legacy pairing with static passkey MITM protection, and that this does not work when the peer is not a phone, but rather a device without a keyboard? If so, it should have the IO capabilities (io_caps) set accordingly, and MITM will not be used.

Br,

Einar

[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.