Teledyne Lecroy Frontline BPA 600, Hardware And Software User Manual, Page: 326 / 348

Clicking on the
MSC
LE LL tab will show the process of encrypting a session link. Clicking on Frame# 39,617
displays the LL_ENC_REQ command from the master to the slave. In the
MSC
below this command you will
see the data transferred that includes SKD
master
used to generate the LTK. At Frame# 39,623 the slave
responds with LL_ENC_RSP sending SKD
slave
to generate LTK at the master. Up to this point all transmissions
are unencrypted. For this example the slave sends the request to start encryption, LL_START_ENC_REQ, at
Frame#39,635. The master responds with LL_START_ENC_RSP at Frame# 39,639, and finally the slave
responds with LL_START_ENC_RSP at Frame# 36,649. At this point the session link is encrypted.
Figure 28 - MSC link Layer Encryption (BPA 600 low energy capture)
A.4.7.4 Viewing Decrypted Data
In the ComProbe software
Frame Display
click on the
LE BB
tab. Search in the
Summary
pane for
Decryption Initiated = Yes frames. In the example depicted in the following figure, Frame# 39723 is selected.
In the
Decoder
pane LE BB shows that the decryption was initiated and decryption was successful. In LE Data
we see the Encrypted MIC value. The MIC value is used to authenticate the sender of the data packet to
ensure that the data was sent by a peer device in the link and not by a third party attacker. The actual
decrypted data appears between the Payload Length and the MIC in the packet. This is shown in the
Binary
pane below the
Summary
pane.
TELEDYNE LECROY Appendicies
318 Frontline BPA 600 Hardware & Software User Manual