BLE CC2540 Sniffining Issue

Sangram Jadhav

Other Parts Discussed in Thread: CC2540

Hello,

We are using the CC2540 to sniff the communication between 2 BLE devices (Master and Slave). The data channel packet appear to be in encrypted format. I have a believe the packets are decrypted by the CC2540 using the "Long Term Key"

provided in the Packet Sniffer application. Please confirm the understanding.

The problem is we are unable to parse our application data from the slave as expected from the hex data bytes captured from the sniffer. The query is:

Is the data in the current log encrypted? If so then, is the key intelligent chosen to decrpyted by the Packet Sniffer device of PC application if no Long term key is given?

How to decide on the Long term key, as per our current status?

Please find the attached screen shot.

Please reply ASAP.

With Thankful Regards,

Sangram

Symphony Teleca

over 11 years ago

0 Maulik Vaghela over 11 years ago

Expert 2500 points

Hi,

Yes, data is encrypted.

I guess devices are paired that's why you are able to see only encrypted data.

If you sniff data when devices starts pairing, i.e., when devices are advertising then you might be able to get the long term key. I don' t have much experience with it but when I was able to get long term key in sniffer itself when I followed communication process from start.

0 Sangram Jadhav over 11 years ago in reply to Maulik Vaghela

Prodigy 60 points

HI Maulik,

Thanks a lot!

Can you please tell which part of the BLE commands does have Long -Term Key and how to parse and recognize the packet to find the LTK.

Sanrgam

0 Sangram Jadhav over 11 years ago in reply to Sangram Jadhav

Prodigy 60 points

HI Maulik,

I was able to parse the data!, problem was I was not pairing the BLE devices while sniffing, so LTK is not a issue any more(the sniffer SW picks the LTK from the control packet). Thanks a lot!

Sangram

Bluetooth®︎

Bluetooth forum

BLE CC2540 Sniffining Issue