# Telehealth Secure Solution to Provide Childhood Obesity Monitoring
## 5 Experimental Results  
The proposed telehealth secure communication scheme for childhood obesity monitoring was implemented using MATLAB R2015a software [37]. The hardware used was a laptop computer with Intel CORE i3 CPU 2.0 GHz, 64-bit windows 10 operating system, and 8 GB of RAM. The main objectives of this implementation were to transmit childhood obesity parameters securely by using the architecture in Figure 3 and to determine its level of security and efficiency using the MATLAB software environment. We assumed that parents had collected the data previously using smartphones and Bluetooth communication with the activity bracelets used by their children. In experimental results, we considered a simulated scenario based on five children (five users), with plain text fictitious data related to their health, such as exercise and sleep (Table 2). Such fictitious data are similar to real cases as presented in data sets in [38]. We considered that children used an activity bracelet to measure the data. Then, the results are based on the evaluation of the proposed multi-user secure communication for secure telehealth monitoring. The experimental results are limited to children's weekly exercise and sleep data. The times of the Fell asleep at and Woke up parameters are converted to a string of just numbers, where the hour is multiplied by 60 plus the minutes, e.g., 8:08 Hrs. are converted to 488, as seen in Table 2 for the Woke up parameter of User 1. For the encryption process, the secret key for each user is defined in Table 3. There are two initial conditions and two control parameters for each Henon map and user. Since the 64-bit double floating-point format is used, each value has 15 decimal precisions. Since all of the encrypted data of the children are transmitted together to the physician by using just one communication channel, the proposed scheme can reduce the cost of implementation. \begin{table}
\begin{tabular}{l c c c c c} \hline \hline  & **User 1** & **User 2** & **User 3** & **User 4** & **User 5** \\ \hline Weekly steps (mean) & 12,891 & 10,616 & 12,221 & 10,829 & 14,504 \\ Weekly activity (mean min) & 160 & 134 & 154 & 144 & 184 \\ Weekly distance (km) & 47 & 30 & 38 & 31 & 44 \\ Calories burned (cal) & 1208 & 700 & 1039 & 745 & 1023 \\ Sleep (mean min) & 533 & 480 & 562 & 511 & 546 \\ Deep sleep (mean min) & 136 & 217 & 220 & 149 & 146 \\ Light sleep (mean min) & 396 & 262 & 342 & 181 & 400 \\ Fell asleep at & 675 & 326 & 630 & 657 & 651 \\ Woke up at & 488 & 447 & 472 & 465 & 481 \\ Awake time (mean min) & 0 & 0 & 0 & 16 & 2 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Plain text fictional data of 5 users (children). The cryptogram generated is shown in Figure 4. Figure 4a presents the cryptogram signal (with additive white Gaussian noise (AWGN) and a signal-to-noise ratio (SNR) of 1 dB based on MATLAB [37]) to be transmitted over an unsecured channel with 19,200 data points (64-bit double floating-point format IEEE 754 standard [39]). Figure 4b shows the first 1000 data points of the cryptogram. In Figure 4c, the AWGN noise added to the cryptogram is shown. The cryptogram is sent by the parents over an unsecured channel, such as the Internet, to the corresponding physician or specialist. The encryption algorithm is considered public, but the secret key must be confidential between the authorized parties (parents and physicians). An intruder could acquire the cryptogram from the Internet but only the authorized receiver who has the correct secret key can recover the plain text or the weekly monitored data of the children. The secret keys to recover the plain text of the five users (children) are shown in Table 4. Note that only three keys are correct (users 2, 3, and 5), whereas the other two are incorrect in the last digit in \(x_{0}\) and \(y_{0}\), respectively (users 1 and 4).