zWave is a wireless technology developed to address the wireless communication between devices which are low power and low cost. The ZWave standard operates on the ITU standard (G.9959) and operates at 908.42 MHz in the US (868.42 MHz in Europe) using a mesh networking topology.

Zwave Network

The z-wave network consists of controllers (one primary controller and more than one secondary controllers) and slaves. Controller devices are the nodes in a z-wave network which initiates control commands. It also sends out the commands to other nodes. The slave devices are the nodes which replies based on command received and also execute the commands. Slave nodes also forward the commands to other nodes in the network. This makes it possible for controller to establish communication with the nodes who are not in radio frequency region.

Z-Wave Security Model

Following are features used in z-wave security:

• Message Freshness: 64 bit Nonce
• 128 bit random network key:Kn
• Encryption: AES-OFB
• Data Authentication: AES-CBCMAC
• 128 bit Cipher and MAC Keys: Derived from Kn
• Custome Jey Establishment Protocol, as explained below.