USER MANUAL PREVIEW
PTM 535BZ
–
BLUETOOTH AND ZIGBEE GREEN POWER PUSHBUTTON TRANSMITTER
© 2021 EnOcean | www.enocean.com
F-710-017, V1.0
PTM 535BZ User Manual | v1.0 | May 2021 | Page 110/112
D.3
Example
For this example, we consider the BLE data telegram payload
0CFFDA034000000001B0561C03
received from a PTM 535BZ with source address
E21510000006
which is authenticated with
security key
1D76A7A0DE93E7F553132D5894CFF99B
.
The last four bytes of this payload (
B0561C03
) are the sender-provided signature which has
to be authenticated (compared against the signature the receiver calculates based on its
own security key).
The variable input parameters are therefore the following:
Parameter
In this example
Source Address
0600001015E2 (little endian representation of E215000019B8)
Input Data
0CFFDA034000000001B0561C03
Input Length
0x0009
Sequence Counter
40000000
Security Key
1D76A7A0DE93E7F553132D5894CFF99B
The constant internal parameters are always the same:
Parameter
In this example
A0_Flag
0x01
(always)
B0_Flag
0x49
(always)
i
0x0000
(always)
Based on variable input data and constant internal algorithm parameters, we can now de-
rive the following variable internal parameters:
Parameter
In this example
Nonce
0600001015E240000000000000
A0
010600001015E2400000000000000000
B0
490600001015E2400000000000000000
B1
00090CFFDA0340000000010000000000
We can now calculate the signature using AES128 and XOR operations.
At the time of writing, a suitable online AES calculator could be found here:
Likewise, a suitable XOR calculator could be found here: