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CC2540: how decrypt the data packet in ti sniffer

alireza sadeghpour
Intellectual 380 points
Part Number: CC2540

hi to all,

i am new in ble and i want use ti sniffer based on cc2540 to learn more about ble, i want sniff an encrypted connection but when i want sniff this connection sniffer show only the encrypted packets, in below pic you can see the result:

as you can see i entered the passkey and also sniffer detected the LTK, but it still show the encrypted packet. and also main data between central and peripheral tranfered through notify charactristic, i also attached dump of connection.

now can any one give me a advice to see decrypted data packets??

passkey_entered.psd

  • 0
    Intellectual 380 points
    some thing that i want to point to that is that at first of connection sniffer show packets and work good, but it seems that suddenly it encounter with a problem and do not even show packets in each connection interval(my connection interval is 25ms).

    and also when i do not send the paring in central and remove authentication Necessity for accessing to chars in peripheral, sniffer work well and show me all packets.
  • 0 in reply to alireza sadeghpour
    TI__Guru 56590 points
    Hello Alireza,
    Based on all the "FCS error" that occur indicate that the sniffer might reside in a noisy RF environment. Try to isolate the devices you sniff and keep them close to the packet sniffer. A metal cookie jar or something with even thicker metal would be good to isolate your 3 devices (Sniffer, Master, Slave) from RF noise.