## 4 Experimental Results and Discussion
### Performance Comparison of NTSA with TEA, XTEA and XXTEA
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**FILE SIZE** & \multicolumn{4}{c}{**DECRYPTION TIME (in milliseconds)**} \\ \hline
**(IN KILO BYTES)** & **TEA** & **XTEA** & **BLOCK TEA (OXTEA)** & **NTSA** \\ \hline
0.37 & 0.058 & 0.136 & 0.068 & 0.055 \\
0.95 & 0.123 & 0.289 & 0.156 & 0.112 \\
1.6 & 0.209 & 0.474 & 0.254 & 0.201 \\
2.6 & 0.332 & 0.691 & 0.371 & 0.323 \\
6.8 & 0.753 & 1.369 & 1.73 & 0.655 \\
8.6 & 0.806 & 2.095 & 1.16 & 0.789 \\
12.2 & 0.903 & 2.228 & 1.365 & 0.890 \\
16.2 & 1.537 & 3.698 & 1.959 & 1.234 \\
26.7 & 1.78 & 4.241 & 2.799 & 1.645 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Time for key size of 48 bits. to the encryption time achieved by TEA, XTEA and XXTEA algorithms. The simplicity in design of NTSA helped the algorithm to achieve lower encryption time with varying key and file sizes. This scenario was also observed with the decryption times presented in Table 5. With decryption also, NTSA achieved lower times compared to its compatriots with a 128-bit key and varying file sizes. NTSA achieved a decryption time of 0.49 ms for a 0.37 kB text file compared to 0.058 ms, 0.143 ms and 0.068 ms achieved by TEA, XTEA and XXTEA respectively for similar text file size. For higher file sizes of 12.2 kB, 16.2 kB, and 26.7 kB, NTSA achieved 1,03 ms, 1.10 ms, and 1.989 ms decryption times, respectively. So even with higher text file sizes, NTSA achieved lower decryption times similar to the results obtained during encryption. With lower encryption and decryption times at 128-bit key, NTSA can become the preferred security algorithm for hand held devices and other embedded IoT devices with different computational capabilities for efficiently transferring text files. Tables 6 and 7 show the encryption and decryption times of the security algorithms for the transfer of a text file with size 0.95 kB. The better performance of NTSA compared to all the existing security algorithms is evident from the obtained results. This is because the NTSA algorithm has a very simple implementation strategy. The TEA and its different variations use complex computations with the key and hence the encryption and decryption time is greater. In Table 6, the encryption time obtained by NTSA for a file size of 0.95 kB with varying key size is compared with the existing algorithms. The key size is varied from 32 bits to 240 bits and the corresponding encryption time is observed. TEA achieved an encryption time of 0.125 ms for a key size of 32 bits while XTEA and XXTEA achieved 0.287 ms and 0.145 ms, respectively. For the same key size, NTSA had an encryption time of 0.07 ms which was much lower compared to all the other security algorithms. For the 96-bit key, XTEA had an encryption time of 0.126 ms, while XTEA and XXTEA had encryption times of 0.265 ms and 0.158 ms, respectively. The encryption time obtained by NTSA for similar key size was 0.093 ms which was much lower than the time achieved by the existing algorithms. This demonstrates the better performance of the \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**FILE SIZE** & \multicolumn{4}{c}{**ENCRYPTION TIME (in milliseconds)**} \\ \hline \hline
**(IN KILO BYTES)** & **TEA** & **XTEA** & **BLOCK TEA (OXTEA)** & **NTSA** \\ \hline
0.37 & 0.059 & 0.125 & 0.068 & 0.51 \\
0.95 & 0.126 & 0.264 & 0.158 & 0.109 \\
1.6 & 0.198 & 0.423 & 0.232 & 0.189 \\
2.6 & 0.332 & 0.686 & 0.384 & 0.221 \\
6.8 & 0.696 & 1.584 & 0.743 & 0.548 \\
8.6 & 0.948 & 1.669 & 1.171 & 0.899 \\
12.2 & 1.277 & 2.807 & 1.535 & 1.02 \\
16.2 & 1.12 & 3.263 & 1.864 & 1.10 \\
26.7 & 2.209 & 5.207 & 2.224 & 1.983 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Time for key size of 128 bits.