# Design and Implementation of a Contextual-Based Continuous Authentication Framework for Smart Homes
## 3 Framework Design
### Contextual Information
#### 3.1.3 Quality of Context Information  
Another important factor regarding retrieved contextual information that is related to security is Quality of the Contextual Information (QoC). The quality is based on the accuracy and trust of the received values. While accuracy is often desirable in applications such as GPS location tracking, [45] mentions that the QoC is only related to the information itself, and does not involve the resource that provides the contextual information or the performed processes. However, we argue that it is also important to confirm the legitimacy of the received information. Consequently, the received data need to be verified as correct and legitimate, as coming from the user or device, and not having been altered during collection or transmission. Thus, it is important to consider QoC regarding the accuracy and trust of the received values. Many different methods [45; 46; 47] can be adopted for measuring the quality of contextual information. The popular approaches include:  
* Statistical analysis, which is based on mathematical models to exclude unreliable values: for example, retrieving the temperature and pressure values from different resources and discarding any anomalous values. Statistical analysis is an effective approach that can be applied especially to environmental contextual information, and also when having multiple resources of the received contextual information. * Confidence value, which is based on assigning different confidence values for the involved authentication tools and the used devices. As an example, physical tokens have higher confidence values than traditional credentials such as username and password. In our work, higher confidence values will be assigned to the retrieved contextual information based on the trust of the related resource. For instance, by considering MAC address spoofing, a MAC address will be assigned a lower confidence value than voltage value. In addition, the confidence level will be assigned based on information resulting from historical analysis as long-term contextual information. We assume that the achieved contextual information is collected from secured resources and examined in real-time. Taking into consideration that authentication can be strengthened by \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Context Type** & **Feature** & **Data** & **Available** & **Requires App or** & **Requires User** \\  & & **Collected by** & **Remotely** & **External API** & **Intervention** \\ \hline \multirow{4}{*}{User Context} & Location (GPS) & Device & Yes & No & No \\  & Access patterns (logs) & Gateway & Yes & No & No \\  & Profile & Device & Yes & No & Yes \\  & Calendar & Device & Yes & Yes & Yes \\ \hline \multirow{4}{*}{Device Context} & Location (Bluetooth) & Gateway & Possible & No & No \\  & Operating System & Gateway & Yes & No & No \\  & Browser & Gateway & Yes & No & No \\  & Voltage value & Device & Yes & Yes & No \\  & Wi-Fi access points & Device & Yes & Yes & No \\  & Used applications & Device & Yes & Yes & No \\  & Battery level & Device & Yes & Yes & No \\  & MAC address & Gateway & Yes & No & No \\  & Motion detection & Device & Yes & Yes & No \\  & Rotation detection & Device & Yes & Yes & No \\  & Compass (environment detection) & Device & Yes & Yes & No \\ \hline \multirow{4}{*}{Network Context} & IP address & Gateway & Yes & No & No \\  & Connection type & Device & Yes & Yes & No \\  & Ping & Gateway & Yes & No & No \\  & Speed & Device & Yes & Yes & No \\  & Trace route & Gateway & Yes & No & No \\ \hline \multirow{4}{*}{Environmental Context} & Lighting & Device & Possible & Yes & No \\  & Temperature & Both & Possible & Yes & No \\ \cline{1-1}  & Pressure & Both & Possible & Yes & No \\ \cline{1-1}  & Humidity & Both & Possible & Yes & No \\ \cline{1-1}  & Loudness & Device & Possible & Yes & No \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Contextual information to be used in the proposed framework.