# Vehicular Alarm System Using mHealth Data and Lightweight Security Algorithms
## Security Algorithms with Lightweight Security
### System Topology  
The security framework is proposed in Figure 5 where the vehicle information system is coming from different sensors positioned at different locations in the vehicle, as depicted in Figure 3. The proposed architecture shows that the different sensors located at different positions in the vehicle will be connected through a smart phone (or other devices) and will transfer the collected information from mHealth devices to the cloud network. However, unauthorized/compromised entities (intruders) can inject modified information into the mHealth system's message to compromise the whole network's activity. To avoid such problems, the sensors' identity or transmitted messages should be checked to ensure that it is coming from authenticated users. Hence, we propose a lightweight secure mechanism so that only authenticated data will be transmitted. We propose to implement the lightweight security framework for mHealth networks. In our system architecture, there are two areas including the wireless cognitive radio network (WCRN) and the vehicle information system. The security mechanism is applied in the WCRN only. In this network, there are three entities, which are outlined below.  
1. Certificate Authority (CA)
2. Primary User Base Station (PUBS) (Primary mHealth Base Station)
3. Primary and Secondary Users (mHealth nodes)  
Cognitive sensor nodes in the WCRN can use the radio more efficiently for transmission in the wireless network. It allows us to construct a network based on the available radio with the combination of cognitive radio nodes and improves the speed and availability of channels for wireless networks. The benefit of using a cognitive radio is its efficient utilization of the spectrum such that the radio can always be available for secondary users when primary users are not using the radio bandwidth. The two types of users include primary users and secondary users. Primary users are those who access the radio network at a high demand, such as ECG sensors in the vehicle information system, which transmit heart-related information frequently. These primary sensors need to send the information with priority. Sensors that do not need to send information urgently such as motion sensors will be considered as secondary users. Depending on the users' radio usage priority, there will be two networks: primary user network (PUN) and secondary user network (SUN) in the proposed architecture. However, each user's identity or transmitted message from the user will be checked to verify the source as an authenticated primary or secondary user. There are three advantages of using cognitive radio (CR) architecture in mHealth networks, which are discussed below.  
* A CR automatically senses a spectrum hole and requires _trust_ from the existing system (i.e., primary system) and regulator to dynamically access the spectrum for information transmission, without creating interference to the primary station (PS).
* A CR may want to leverage another existing cognitive radio to route its packets, even though another CR is not the targeted recipient terminal. It requires _trust_ from another CR.  
* A CR can leverage the PS to forward its packets to realize the goal of packet switching networks. It requires _trust_ from the PS, not only at a network level, but also in the service provider level.  
Considering these advantages of a CRN trust-based authentication infrastructure, the following are included in the mHealth network architecture for secure communication.