## 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 \hline
**(IN KILO BYTES)** & **TEA** & **XTEA** & **BLOCK TEA (OXTEA)** & **NTSA** \\ \hline
0.37 & 0.058 & 0.143 & 0.068 & 0.49 \\
0.95 & 0.125 & 0.276 & 0.179 & 0.101 \\
1.6 & 0.195 & 0.43 & 0.233 & 0.174 \\
2.6 & 0.324 & 0.673 & 0.388 & 0.311 \\
6.8 & 0.678 & 1.57 & 0.75 & 0.556 \\
8.6 & 0.936 & 1.641 & 1.21 & 0.889 \\
12.2 & 1.241 & 2.764 & 1.538 & 1.03 \\
16.2 & 1.111 & 3.184 & 1.956 & 1.10 \\
26.7 & 2.179 & 5.178 & 2.193 & 1.989 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Time for key size of 128 bits. proposed approach NTSA, compared to all the existing security algorithms in IoT networks with varying key sizes. Tables 8 and 9 show the encryption and decryption times of the security algorithms for the transfer of a text file with size 12.2 kB with varying key sizes. The encryption time achieved by TEA, XTEA and XXTEA for a key size of 32 bits was 1.173 ms, 2.287 ms, and 1.649 ms, respectively, which was much higher compared to 1.009 ms obtained by NTSA for a similar key size. Even for a key size of 96 bits, NTSA achieved an encryption time of 1.10 ms which is lower than the values obtained by all the other existing security algorithms for similar file size. For a key size of 240 bits, NTSA had an encryption time of 1.2 ms which was much lower compared to all the existing algorithms. Thus, for smaller and larger key sizes, NTSA achieved lower encryption time compared to all the existing security algorithms in IoT networks. This scenario is also observed with the decryption times presented in Table 9. NTSA achieved a decryption time of 1.025 ms, 1.155 ms, and 1.388 ms for a key size 160 bits, 192 bits, and 240 bits, respectively. This time achieved by NTSA was lower than the times obtained by TEA, XTEA and XXTEA for similar key sizes in the IoT network. This assures the better performance of NTSA compared to all the existing algorithms with varying key sizes in IoT networks. Tables 10 and 11 presents the results obtained in encryption and decryption time with NTSA, TEA, XTEA and XXTEA for a text file size of 26.7 kB with varying key sizes from 32 bits to 240 bits. The encryption time achieved by TEA, XTEA and XXTEA for a key size of 32 bits is 2.253 ms, 4.459 ms, and 2.339 ms, respectively, which is much higher compared to 1.772 ms obtained by NTSA for a similar key size. Even for a key size of 96 bits, NTSA achieved an encryption time of 1.856 ms which was lower than the values obtained by all the other existing security algorithms for similar file size. NTSA also achieved an encryption time of 1.887 ms, 1.662 ms, and 1.912 ms for 160 bits, 192 bits and 240 bits' key sizes. Thus, from the results it is evident that NTSA achieved much lower encryption times compared to all the existing algorithms in IoT networks. This scenario is also verified in Table 11 which presents the decryption time obtained by these algorithms for varying key sizes. The simplicity in design enables NTSA to achieve much lower encryption and decryption times in IoT networks. This would \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**KEY SIZE** & \multicolumn{4}{c}{**ENCRYPTION TIME (in milliseconds)**} \\ \hline
**(IN BITS)** & **TEA** & **XTEA** & **BLOCK TEA (OXTEA)** & **NTSA** \\ \hline
32 & 0.125 & 0.287 & 0.145 & 0.07 \\
48 & 0.125 & 0.264 & 0.162 & 0.083 \\
64 & 0.125 & 0.246 & 0.17 & 0.088 \\
96 & 0.126 & 0.265 & 0.158 & 0.093 \\
128 & 0.126 & 0.264 & 0.158 & 0.097 \\
160 & 0.114 & 0.271 & 0.154 & 0.100 \\
192 & 0.125 & 0.279 & 0.144 & 0.100 \\
240 & 0.125 & 0.279 & 0.145 & 0.113 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Encryption time for file size 0.95 kB.