Issues with Zephyr Peripheral NFC Pairing Example

RE: Issues with Zephyr Peripheral NFC Pairing Example

andreribeiro423 — Fri, 05 May 2023 10:23:22 GMT

Sure! The problem was that as advertising is only performed after touching the NFC antenna, the intended device does not appear in the Wireshark device list during the first pairing. As the exchange of SMP packets takes place before advertising starts, if the device is not selected in the list of devices in Wireshark, the SMP packets do not appear. Thus, in the following pairings, the device is already displayed in the device list and if it is selected, the SMP packets are already displayed.

RE: Issues with Zephyr Peripheral NFC Pairing Example

Simonr — Fri, 05 May 2023 07:17:37 GMT

You're welcome to share your solution here so that DevZone users with the same issue in the future might find it helpful.

Glad you figured it out!

-Simon

RE: Issues with Zephyr Peripheral NFC Pairing Example

andreribeiro423 — Thu, 04 May 2023 17:31:33 GMT

Hi! I already understood what my problem was. Thanks for all the help!

RE: Issues with Zephyr Peripheral NFC Pairing Example

Simonr — Thu, 04 May 2023 10:52:36 GMT

But the Security Manager Debug mode is something completely different that transmits the keys over BLE. Have you followed the "Sniffing the pairing procedure" guide that tells you to enter the private key into the input field of Wireshark in a big-endian, hexadecimal format with a leading "0x" on your end? If so you will see BLE packets on the sniffer trace. What nRF device are you using for sniffing by the way?

Best regards,

Simon

RE: Issues with Zephyr Peripheral NFC Pairing Example

andreribeiro423 — Tue, 02 May 2023 14:01:43 GMT

But if I enable Security Manager Debug Mode, the connection uses the debug keys specified in the Bluetooth Core Specification Vol. 3, Part H, 2.3.5.6.1 and anyone is able to decipher encrypted air traffic. So, the sniffer should be able to join in on the OOB pairing because uses the same keys to decrypt the encrypted packets (debug private/public key pair described in Core Specification Vol. 3, Part H, 2.3.5.6.1).

RE: Issues with Zephyr Peripheral NFC Pairing Example

Simonr — Tue, 02 May 2023 08:10:30 GMT

I think the reason you're not seeing this data on Wireshark is because the OOB pairing share encryption keys/authentication data over the "alternative" communication channel, in this case being NFC.

Wireshark won't be able to sniff any data transferred over NFC as it's a completely different protocol and frequency than BLE.

Best regards,

Simon