Central to update bonding info when peripheral has deleted it.

[User1321]

Hi Nordic, 

In this question: https://devzone.nordicsemi.com/f/nordic-q-a/56529/how-to-check-or-read-the-list-of-bonded-device-from-nrf52832
It was discussed to update the bonding parameter on the peripheral side when the central (an external Central) deleted them. That works fine for the peripheral side but not for the central, in that case the Central tries continuously to bond always getting 'failure' result. 

Can it be adjusted to the central as well? i.e. when the central has a bonding data but the peripheral has deleted it, then can the central detect this and update its bonding info?

I'm using the SDK 15.3 with S140

Thank you in advance 

[Hung Bui]

Hi, 

On the central side, since there is most likely no security request from the peripheral, you can't use allow_repairing to allow a new bond. 

You would need to catch PM_EVT_BONDED_PEER_CONNECTED event, to know that you have connected to a bonded peer. Then you will receive either PM_EVT_CONN_SEC_SUCCEEDED when the bonding is successful. Or PM_EVT_CONN_SEC_FAILED event when bonding is failed. In that case you would need to call pm_peer_delete() to delete the specific peer that you just connected. And then try to connect and bond again. 

Note that this behavior is not suggested as it expose a risk that an attacker can pretend to be the peripheral and it has lost the bond information. You will then delete the original bond information and can cause it to unable to connect to the original peer or that the attacker can spoof that it's the original peer. 

So usually it should involve the approval of the End User to delete the peer information (just like on the phone, you need to "Forget this device" before you can establish a new bond.