# SIMECK-T: An Ultra-Lightweight Encryption Scheme for Resource-Constrained Devices
## 2 Methodology
### Implementation
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Rounds** & **64 bit** & **Avg Bit** & **Min B. Fl.** & **Max B. Fl.** & **Time (s)** \\  & **Blocks** & **Flips** & **Min B. Fl.** & **Max B. Fl.** & **Time (s)** \\ \hline
1 & \(10^{6}\) & 32.00 & 3 & 55 & 12.44 \\
2 & \(10^{6}\) & 32.00 & 10 & 54 & 12.77 \\
3 & \(10^{6}\) & 32.00 & 10 & 55 & 13.13 \\
4 & \(10^{6}\) & 32.00 & 8 & 55 & 13.73 \\
5 & \(10^{6}\) & 32.00 & 11 & 54 & 13.77 \\
5 & \(10^{2}\) & 32.04 & 18 & 49 & 0.0014 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Avalanche effect data for SIMECK-R cipher across rounds. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Key Guess** & **Number of Pairs** & **Bias** \\ \hline EE 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 & \(10^{8}\) & 0.011891\% \\
1A 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 & \(10^{9}\) & 0.004373\% \\
89 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 & \(10^{9}\) & 0.004798\% \\ AC 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 & \(2^{32}\) & 0.001758\% \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Best key guesses and biases. Table 9 shows no bias far from zero, which means that no interesting pattern is found. The goal is to identify suspect relationships (differential trails) when the difference between two plaintext blocks encrypted with the same password is known. ### Statistical Evaluation Metrics

#### 4.3.1 Chi-Squared

For 1 GB of data, we obtain a value of 251.546, which is greater than 0.05, meaning that the histogram is uniform. The full-round SIMECK has a value of 244.252 and full round TEA is at 268.299. #### 4.3.2 Encryption Quality

Our cipher yielded an encryption quality of \(8.853\times 10^{6}\). The higher this value, the better the encryption quality of the cryptosystem. For full-round SIMECK, the encryption quality is \(7.273\times 10^{6}\), while full-round TEA has an encryption quality of \(7.467\times 10^{6}\). The proposed SIMECK-T has a better encryption quality. #### 4.3.3 Mean Square Error

The mean square error obtained from our experiments is \(1.09221\times 10^{4}\). The full-round SIMECK has a mean square error of \(1.09225\times 10^{4}\), while the full-round TEA has a mean square error of \(1.09222\times 10^{4}\). These values are comparable with those of SIMECK-T.

#### 4.3.4 Peak Signal-to-Noise Ratio

Low values of the PSNR indicate a secure cryptosystem. The value resulting from our experiments is 25.7373. The full-round SIMECK has a PSNR value of 25.7368, while the full-round TEA has a PSNR of 25.7372. These values are similar to SIMECK-T.

#### 4.3.5 Structural Similarity Index Measure

The value obtained in our experiments for the measure of the structural similarity index is \(1.362\times 10^{-2}\). Full round SIMECK has \(1.362\times 10^{-2}\) and full round TEA has \(1.362\times 10^{-2}\). The values are comparable with those of SIMECK-T.

#### 4.3.6 Normalized Cross-Correlation

Our cryptosystem yielded a normalized cross-correlation value of \(2.630\times 10^{-5}\). The normalized cross-correlation obtained by full-round SIMECK is \(-7.306\times 10^{-6}\), while full round TEA obtains a value of \(5.086\times 10^{-6}\). In all cases, the normalized cross-correlation is close to 0.