Pairing two devices nRF52

[Arepa]

Hi all,

I am working on my Central device to request pairing to my peripheral (I asked about the peripheral in my previous post, both are running a nRF52DK and SDK13.

I am having the following 'issue' at the moment I don't know if I am performing LESC + Just Works or Legacy + Just Works.

My sniffer captures have a big difference when I use nRF connect (version PC using a nRF51DK) to perform the pairing with a nRF52DK running the lesc_multirole vs two nRF52 Boards running lesc_multirole example. I both cases the example code was unmodified

my sec_parms are:

sec_params.bond           = true;
sec_params.mitm           = false;
sec_params.lesc           = true;
sec_params.keypress       = false;
sec_params.io_caps        = false;
sec_params.oob            = false;
sec_params.min_key_size   = 7;
sec_params.max_key_size   = 16;
sec_params.kdist_own.enc  = 1;
sec_params.kdist_own.id   = 1;
sec_params.kdist_peer.enc = 1;
sec_params.kdist_peer.id  = 1;

Test1

• I got the following sequence when two nRF52DK are running the lesc_multirole example with not display or input

also in the sniffer capture it looks like is using a 000000 passkey and not the Elliptic-curve for the encryption and it is not pairing

Test2

• For otherwise when I am running the lesc_multirole example on a nRF52 like a peripheral and the central using the connecitivy firmware for nRF Connect (PC version) this sequence differs a lot when are 2 devices with no display or inputs, and it looks is generating random values and it is pairing:

why are so different the sequence when using a nRF connect/PC/Smartphone like central vs a nRF52DK running the lesc_multirole example?.

An additional question LESC + 'Just works' requires bonding?

Thanks

[Hung Bui]

Hi Arepa,

It's hard to understand what you are trying to ask here. Please state it clearly in bullet points in different test cases that you did. Which device you used, which firmware running on which side and the sniffer trace. The full sniffer trace. What in your 5.png is just the encryption request, not the pairing request and how they paired.

Also the second attachment is missing.

LESC+"Justwork" doesn't require bonding, you can do pairing. There is no STK, it's just the LTK will not be stored.

[Arepa]

Hi Hung, I apologize for first post. I updated it :)

how can I generate the pairing request from the central side to the peripheral? I tried calling pm_conn_secure() inside my service discovery event and it should call sd_ble_gap_authenticate() internally, but looks like sd_ble_gap_authenticate is not being called

[Hung Bui]

Hi Arepa,

As I mentioned the first image doesn't show how they are bond. It only showed how the 2 are reencrypting the connection after the bonding is done. You need to erase bond information on both sides before you test again and capture the sniffer trace.