"strange" bad MIC packet

RE: "strange" bad MIC packet

astella — Sat, 17 Sep 2022 19:15:23 GMT

Thank you

RE: "strange" bad MIC packet

Hung Bui — Fri, 16 Sep 2022 12:44:32 GMT

Hi Stella,

From what I I can see the CRC was correct. So it might be not the packet corruption issue.

However, it's most likely not the issue with the data packet. And more likely the glitch with the sniffer itself.
Normally if a packet has a wrong MIC, the peer device should terminate immediately.

You can see that the Bluetooth core spec v5.2 Vol 1 Part F section 2.58:

In your case it seems the connection continued normally.

I would suggest to use another sniffer as reference to sniff in parallel to cross check, preferably a professional BLE sniffer for example Ellisys or Frontline.

RE: "strange" bad MIC packet

astella — Fri, 16 Sep 2022 10:41:23 GMT

Hi Hung, thank you. Here the sniffing trace

devzone.nordicsemi.com/.../prova_5F00_ol.pcapng

RE: "strange" bad MIC packet

Hung Bui — Fri, 16 Sep 2022 10:35:58 GMT

Hi Stella,

Could you please check if the CRC value of the packet is matched, not an incorrect CRC ?
If possible please upload the sniffer trace file here.

I suspect that it's simply a corrupted packet received by the sniffer trace. In that case we will have CRC mismatch.