LE secure connection doesn't work

[espruino-discuss3]

Posted at 2021-09-05 by ermano

Hi all,

I have Bangle.js and Puck.js devices but couldn't establish LE secure connections between them.

Puck.js has the following service configuration:

NRF.setSecurity({lesc:1});
NRF.setServices({
  0xBCDE : {
    0xABCD : {
      value : "Hello",
      readable : true,
        security: {
          read: { // optional
            lesc: true
          }
        }
      }
    }
});

Bangle.js also has the LE secure connections enabled with the following configuration:

NRF.setSecurity({lesc:1});

Nevertheless, when Bangle.js connects to Puck.js and accesses to the read characteristic, it fails to read.

I also tried to connect to the read characteristic using the NRF connect application. After I connect to Puck.js and try to read the value of characteristic, it triggers bonding and stuck at that stage with no success.

Is there a known issue with the lesc or am I missing something?

Thanks for the support in advance...

[espruino-discuss3]

Posted at 2021-09-14 by @gfwilliams

It could be that the Bangle doesn't automatically start the bonding procedure for a secure connection, and so the read fails. You could try startBonding?

http://www.espruino.com/Reference#l_BluetoothRemoteGATTServer_startBonding

gatt.getSecurityStatus() is also a good way to check the status of the link, like whether you are bonded or not

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Posted at 2021-09-14 by ermano

Hi Gordon,

Thanks for the response. I tried the same with a different setup: Bangle.js being central (scanning advertisements) and a peripheral running on an external nRF board.

• In NRF documentation, I saw that for Level-4 LESC, authentication is also mandatory so eventually it has to be lesc:1, mitm:1.
• The peripheral starts the bonding process by generating a pass key and I developed a keyboard app on Bangle.js to enter this key; nevertheless received the attached error on the peripheral. (public key is not valid)
• When I use nRF connect app on my phone to pair with the peripheral, the bonding works properly but not from my Bangle.js with the setting {lesc:1, mitm:1, keyboard:1}.

Any clue why I get this "public key is not valid" error?

Thanks again for the support...

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Attachments:

• LESC error.PNG

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Posted at 2021-09-15 by @gfwilliams

Ahh, yes, I didn't mention that but only certain combinations for setSecurity work and unfortunately the Nordic SDK doesn't always report back when some settings don't make sense.

Any clue why I get this "public key is not valid" error?

I'm afraid not. I guess it's not referring to the passkey you entered? Maybe Nordic Devzone has some ideas.

The odd thing is I'm pretty sure I have had this working, because the passkey pairing on Central code was implemented for a user that needed it for his project.