## 3 Proposed Security Improvement Framework (SIF) Using Zigbee Protocol  
We have proposed a Security Improvement Framework (SIF) using Zigbee protocol for securing the Zigbee network in the IoT framework. Figure 3 shows the block diagram of the proposed SIF. The physical layer of this Security Improvement Framework (SIF) is based on IEEE 802.15.4 standard. It is the closest layer to the hardware which controls and communicates with the radio transceiver directly. It handles all tasks involving the access to the Zigbee hardware, including initialization of the hardware, channel selection, link quality estimation, energy detection measurement, and clear channel  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Threats** & **Proposed Method** \\ \hline Physical & Algorithm-1 (KY AES Encryption Key and Physical Control Object) \\ Replay & Algorithm-2 (KY AES Encryption Key and Replay Control Object) \\ Flooding & Algorithm-3 (KY AES Encryption Key and Flooding Control Object) \\ \hline \hline \end{tabular}
\end{table}
Table 1: Proposed alleviation methods used in the Security Improvement Framework (SIF).  
Figure 2: Denial of Service (DoS) attacks at the OSI layers of Zigbee protocol.  
assessment to assist the channel selection. This layer does modulation and demodulation operations upon transmitting and receiving signals, respectively. It supports three frequency bands, 2.45 GHz band that uses 16 channels, 915 MHz band that uses 10 channels, and 868 MHz band that uses only 1 channel. All frequency bands use Direct Spread Spectrum Sequencing (DSSS) access mode.  
The Medium Access Control (MAC) layer provides an interface between physical layer and network layer. This layer is responsible for reliable transmission of data by accessing different networks with the carrier sense multiple access collision avoidance/carrier detection (CSMA/CD). This provides two services: MAC data services and MAC management service interfacing to the MAC sublayer management entity (MLME) service access point, called MLMESAP. The MAC data service enables the transmission and reception of MAC Protocol Data Units (MPDUs) across the PHY data service. Network layer interfaces between application layer and MAC Layer. Network layer takes care of all network-related operations such as network setup, end device connection and disconnection to network, routing, device configurations, and so on. It supports three network topologies: star network, tree network, and mesh network. We have used KY AES Encryption in security management instead of default key configuration provided by the manufacturer.  
The application support sublayer is used to provide an interface between the network layer and various data management services. These services are provided with the help of application objects and Zigbee device objects. Zigbee Device Objects (ZDOs) are used to perform various management tasks including security management, network management, and binding management. They are also useful to define the types of devices used in the network. ZDO provides an interface between application layer objects and the APS layer in Zigbee devices. It is responsible for detecting, initiating, and binding other devices to the network. Security Service includes methods for key establishment, key transport, frame protection, and device management. We have proposed three modules: Physical Attack Control  
Figure 3: Proposed Security Improvement Framework (SIF) of Zigbee network in the IoT platform.  
Object, Replay Attack Control Object, and Flooding Control Objects in Application Framework which can detect and protect from Physical, Replay, and Flooding Attacks.