User's Manual

USER MANUAL

PTM 215ZE – 2.4 GHz IEEE 802.15.4 Pushbutton Transmitter Module

4.1 Authentication Implementation

PTM 215ZE implements telegram authentication according to the ZigBee Green Power spec-

ification. It uses AES128 in CCM (Counter with CBC-MAC) mode as described in IETF

RFC3610. At the time of writing, the RFC3610 standard could be found here:

https://www.ietf.org/rfc/rfc3610.txt

The 13 Byte CCM Nonce (number used once – unique) initialization value is constructed as

concatenation of 4 byte Device ID, 4 byte Device ID again, 4 byte Sequence Counter and 1

status byte of value 0x05.

Note that both Device ID and Sequence Counter use little endian format (least significant

byte first).

Figure 8 below shows the structure of the AES128 Nonce.

Figure 8 – AES128 Nonce structure

The AES128 Nonce and the 128 bit device-unique security key are then used to calculate a

32 bit signature of the authenticated telegram payload shown in Figure 9 below.

Figure 9 – Authenticated payload

The calculated 32 bit signature is then appended to the data telegram payload as shown in

chapter 3.3.

The security key required for the telegram authentication can be obtained in two ways:

 Product DMC code

Each PTM 215ZE device contains a product label with a DMC code that identifies the Source

ID and the Private Security Key used by this device, see below.

 Commissioning telegram

The security key is transmitted as part of the commissioning telegram, see chapter 5.3