Teledyne LeCroy Merlin II - Users Manual - Manual (Page 150)

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Merlin II Protocol Analyzer User’s Manual CATC SW Version 2.50
10.11 Encryption
Bluetooth encryption is a multi-staged process that provides devices with
secure, encrypted communications. The process begins with a device
prompting the user for a Personal Identification Number (PIN). When the
right PIN is entered, the Slave begins an encryption setup dialogue with the
Master. At the beginning of this dialogue, the Slave and the Master agree
on a Link Key. A Link Key is a 128-bit value that the two devices use for
authentication. When the Slave and Master agree on a Link Key, the Slave
then negotiates for the transfer of the Encryption Key from the Master
device. The Encryption Key is used to encrypt and decrypt messages. Once
the Encryption Key is transferred, both devices use it to encrypt all
subsequent communications.
In order for Merlin II to decode encrypted traffic, it needs the Link Key for
each Master-Slave connection for which encryption will be used. If you
know the Link Key, you can enter the Key into the Encryption Options
dialog box. If you do not know it, you give Merlin II the PIN for a device
and allow Merlin II to discover the Link Key on its own. Once Merlin II has
the Link Key, it can capture the rest of what it needs by listening to the
Master and Slave devices as they negotiate for the Encryption Key.
Note - The encryption settings here are for the Merlin II only. The
BTTrainer has its own encryption settings.
Note - There is no need to configure Encryption settings if Merlin II is used
to record BTTrainer traffic.
Configuring Merlin II for Encryption
For Merlin II to successfully decrypt traffic, two steps need to be performed:
1) Merlin II needs to be given the PIN or Link Key for each Master-Slave
connection; and 2) Recording needs to be begun before the Slave connects
to the Master. If recording is begun prior to the creating the Master-Slave
connection, Merlin II will be able to obtain the encryption key and decode
encrypted traffic.
The following steps show how to configure Merlin II for encrypted traffic.
Step 1 Select View >Device List
The Device List appears.