USER MANUAL
PTM 215B – BLUETOOTH
®
PUSHBUTTON TRANSMITTER MODULE
© 2019 EnOcean | www.enocean.com
F-710-017, V1.0
PTM 215B User Manual | v1.9 | June 2019 | Page 81/85
C.3
Examples
The following four chapters give step by step examples based on one actual device and 0 /
1 / 2 or 4 byte of optional data.
C.3.1
Data telegram without optional data
For this example, we consider the following telegram payload received from a PTM 215B
with the source address
E215000019B8
and security key
3DDA31AD44767AE3CE56DCE2B3CE2ABB
:
0C FF DA 03 5D 04 00 00 11 B2 FA 88 FF
The last four bytes of this payload (
B2 FA 88 FF
) 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
B819000015E2 (little endian representation of E215000019B8)
Input Data
0CFFDA035D04000011
Input Length
0x0009
Sequence Counter
5D040000
Security Key
3DDA31AD44767AE3CE56DCE2B3CE2ABB
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
B819000015E25D040000000000
A0
01B819000015E25D0400000000000000
B0
49B819000015E25D0400000000000000
B1
00090CFFDA035D040000110000000000
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:
http://testprotect.com/appendix/AEScalc
Likewise, a suitable XOR calculator could be found here:
