# Telehealth Secure Solution to Provide Childhood Obesity Monitoring
## 4 Proposed Multi-User Secure Monitoring Scheme  
We propose a telehealth scheme that allows for the remote monitoring of the risk factors that contribute to the potential development of childhood obesity and overweight. The data will be collected by parents and by means of non-intrusive electronic devices, such as a smart phone, to process the data and send them securely through the communication system to health professionals. The specialist will be able to evaluate the level of obesity, if present, or its risk of occurrence in children and adolescents (6 years and older), and provide parents with clear, accurate, and meaningful information and recommend behavioral interventions that promote a better weight status for the children. The data obtained from the children by means of an activity bracelet (non-intrusive devices) are synchronized with the parents' smartphone. The system developed for this scheme, will show a weekly report to the parent, in addition to transferring such data to the physician every 6 months or in shorter periods of time, depending on the degree of obesity of the child, and as established by the health professionals. In the proposed telehealth monitoring system, multi-user encryption uses chaotic system that are combined with the code-division multiple access (CDMA) technique and spread spectrum technology to provide data privacy and transmission by using just one communication channel (Internet as insecure public channel) between parents and physicians. The general scheme of the architecture of telehealth is shown in Figure 3. \begin{table}
\begin{tabular}{c c} \hline \hline
**Age Group (years)** & **Recommended Sleep (hours)** \\ \hline \textless{}5 & \textgreater{}11 \\ \textless{}10 & \textgreater{}10 \\ \textgreater{}10 & \textgreater{}9 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Recommended sleep duration hours. Figure 3: Architecture of the proposed transmission of medical information in a multi-user network. First, children's physical activity and sleep hours will be monitored daily using activity bracelets. When this information on risk factors is outside the recommended ranges, a warning will be sent to the parent's smart phone by using a Bluetooth communication protocol to invite them to motivate their children to comply with the recommendations. Then, parents, in agreement with their health professionals, will take frequently take the anthropometric measurements of their children, which will in turn be sent to the health professionals using the Internet (4G, 5G, or Wi-Fi protocol), with the encrypted weekly report of physical activity and sleep hours, in addition to the categorization of the data as shown in Figures 1 and 2. Telemedicine is a valuable technology that link clinicians with patients to ensure they make long-term lifestyle changes, it could be making health more affordable reducing distance limitations by exchanging information about a diagnosis, healthcare, and disease prevention between the doctor and the patient through electronic means [15], and for this reason, it is important to assure data integrity. The encryption algorithm of [PERSON] et al. [22], which is based on the chaos and spread spectrum technique with symmetric-key cryptography, is used as a reference to provide information confidentiality in the proposed communication scheme. The encryption algorithm is briefly transcribed and adapted to the propose communication scheme as follows:  
1. The secret key is defined for each child-parent-specialist in a symmetric-key cryptography. 2. The plain text is defined as a vector of 10 \(\times\) 16-bit unsigned integer for \(N\) users. The binary plain text is coded to non-return zero (NRZ), i.e., 1 for \"1\" and \(-1\) for \"0\". 3. The NRZ plain text of each user is modulated with binary phase shift key (BPSK) using a carried signal defined as cosine signal at 1 Hz, 1 amplitude, and 50 samples per cycle. 4. The chaotic two-dimensional Henon map is used for each user, which is defined as follows: \[