## 2 Materials and Methods
### Overview of ESRO-SRO Algorithm
\begin{table}
\begin{tabular}{l l l l l l} \hline \hline
**Average HOPS (\%)** & & & & & \\ \hline
**EC (\%)** & **ESRO-SRP** & **BRUe-IoE** & **ORP-FANET** & **UAVE-WSN** & **TR-UAV Swarm** \\ \hline



\hline \end{tabular}
\end{table} 
Table 3: Average HOPS analysis of ESRO-SRP technique with existing algorithms under distinct levels of energy. Figure 4: AHOPS analysis of ESRO-SRP technique under distinct levels of energy. For instance, with an EC of 5%, the ESRO-SRP model has provided a maximal coverage of 97.69%, whereas the BRUe-IoE, ORP-FANET, UAVe-WSN, and TR-UAV Swarm methods have accomplished a decreased coverage of 91.18%, 83.58%, 81.41%, and 73.26%, respectively. Finally, with an EC of 100%, the ESRO-SRP model has provided an enhanced coverage of 48.29%, whereas the BRUe-IoE, ORP-FANET, UAVe-WSN, and TR-UAV Swarm models have accomplished minimal coverage of 33.63%, 16.26%, 15.18%, and 3.24%, respectively. Table 5 and Figure 6 depict a comparative lifetime analysis of the ESRO-SRP algorithm with recent methodologies under distinct levels of energy. The results outperformed in that the ESRO-SRP model has accomplished maximum values of a lifetime under all energy levels. For instance, with an EC of 5, the ESRO-SRP system has provided a higher lifetime of 57 rounds, whereas the BRUe-IoE, ORP-FANET, UAVe-WSN, and TR-UAV Swarm algorithms have accomplished a minimal lifetime of 41, 25, 10, and 1 round, respectively. Moreover, with an EC of 100, the ESRO-SRP model has an obtainable increased lifetime of 176 rounds, whereas the BRUe-IoE, ORP-FANET, UAVe-WSN, and TR-UAV Swarm approaches have accomplished a decreased lifetime of 157, 144, 124, and 107 rounds, respectively. \begin{table}
\begin{tabular}{p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt}} \hline \multicolumn{5}{p{56.9 pt}}{**Coverage (\%)**} \\ \hline
**EC (\%)** & **ESRO-SRP** & **BRUe-IoE** & **ORP-FANET** & **UAVE-WSN** & \begin{tabular}{} **TR-UAV Swarm** \\ \end{tabular}  \\ \hline
5 & 97.69 & 91.18 & 83.58 & 81.41 & 73.26 \\ \hline
10 & 98.78 & 92.81 & 81.41 & 75.43 & 70.01 \\ \hline
15 & 96.61 &



Figure 5: Coverage analysis of ESRO-SRP technique under distinct levels of energy. \begin{table}
\begin{tabular}{l l l l l l} \hline \hline
**Lifetime (No. of Rounds)** & & & & & \\ \hline
**EC (\%)** & **ESRO-SRP** & **BRUe-IoE** & **ORF-FANET** & **UAVe-WSN** & **TR-UAV Swarm** \\ \hline



\hline \end{tabular}
\end{table} 
Table 5: Lifetime analysis of ESRO-SRP technique with existing algorithms under distinct levels of energy. The experimental results ensured the superior outcomes of the proposed model over other models in the IoD environment. ## 4 Conclusions

In this study, a novel ESRO-SRP technique was established for secure communication among the drones in the IoD environment. The presented ESRO-SRP technique mainly aims to derive a set of optimal routes to the destination. In addition, the ESRO-SRP algorithm is derived by the integration of the QOBL concept with the conventional SRO algorithm. Moreover, the presented ESRO-SRP technique derived a fitness function encompassing different input parameters such as RE, distance, and trust degree. The experimental validation of the ESRO-SRP technique is carried out under several aspects, and the results demonstrated the enhancements of the ESRO-SRP model over recent approaches. The ESRO-SRP model has provided an increased PDR of 86%, whereas the BRUe-IoE, ORP-FANET, UAVe-WSN, and TR-UAV Swarm approaches have accomplished a minimal PDR of 79.60%, 73.60%, 67.60%, and 63.20%, respectively. Therefore, the ESRO-SRP technique can be exploited as an effective tool to improve security and network efficiency. In the future, the performance of the ESRO-SRP algorithm will be extended to the integration of lightweight cryptographic techniques. Conceptualization, S.D. and F.S.A. ; methodology, J.S.A. ; software, I.Y. ; validation, F.S.A., J.S.A. and A.M.; formal analysis, A.S.M. ; investigation, A.A.A. ; resources, M.A.D. ; data curation, A.M.; writing--original draft preparation, F.S.A., J.S.A. and M.A.D.