# A Secure and Efficient Three-Factor Authentication Protocol in Global Mobility Networks
## 9 Conclusions  
In this paper, we assessed that [PERSON] et al.'s authentication scheme did not prevent various attacks. Furthermore, we assessed that their protocol could not achieve user authentication. We proposed a secure and efficient three-factor authentication protocol for roaming services in GLOMONET to improve the security flaws of [PERSON] et al.'s scheme. Our scheme was able to resist various attacks, such as masquerade, replay, session key disclosure, and mobile device theft attacks and could ensure anonymity and user authentication. We demonstrated that our scheme achieved secure mutual authentication among the mobile user, the foreign agent, and the home agent by performing BAN logic analysis.  
Furthermore, we assessed a formal security validation analysis of our protocol utilizing the ROR model and AVISPA simulation. We compared the computation costs and security features with existing schemes. The three-factor based proposed scheme provided a great improvement in terms of the security level compared with two-factor based existing schemes and also preserved the low  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Schemes** & **Registration Process** & **Login and Authentication Process** & **Total Cost** \\ \hline [PERSON] et al. [6] & 704 bits & 4992 bits & 5696 bits \\ \hline [PERSON] et al. [8] & 640 bits & 3872 bits & 4512 bits \\ \hline [PERSON] et al. [15] & 640 bits & 4224 bits & 4864 bits \\ \hline [PERSON] et al. [16] & 1184 bits & 1344 bits & 2528 bits \\ \hline Ours & 608 bits & 2528 bits & 3136 bits \\ \hline \hline \end{tabular}
\end{table}
Table 6: Communication cost comparison.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Schemes** & **Registration** & **Login and Authentication** & **Total** & **Total Cost (s)** \\ \hline [PERSON] et al. [6] & \(7T_{h}+1T_{sym}\) & \(17T_{h}+4T_{sym}+8T_{sym}\) & \(24T_{h}+5T_{sym}+8T_{sym}\) & 2.5272 \\ \hline [PERSON] et al. [8] & \(2T_{h}\) & \(17T_{h}+6T_{pw}\) & \(19T_{h}+6T_{pw}\) & 0.3113 \\ \hline [PERSON] et al. [15] & \(5T_{h}+1T_{sym}\) & \(24T_{h}+1T_{m}+3T_{mm}+3T_{sym}\) & \(29T_{h}+1T_{m}+3T_{mm}+4T_{sym}\) & 1.60785 \\ \hline [PERSON] et al. [16] & \(3T_{h}+1T_{mm}\) & \(7T_{h}+2T_{mm}+4T_{sym}\) & \(10T_{h}+3T_{mm}+4T_{sym}\) & 1.6058 \\ \hline Ours & \(5T_{h}\) & \(22T_{h}\) & \(27T_{h}\) & 0.0135 \\ \hline \hline \end{tabular}
\begin{tabular}{c c c c} \hline \hline
**Schemes** & **Registration Process** & **Login and Authentication Process** & **Total Cost** \\ \hline [PERSON] et al. [6] & 704 bits & 4992 bits & 5696 bits \\ \hline [PERSON] et al. [8] & 640 bits & 3872 bits & 4512 bits \\ \hline [PERSON] et al. [15] & 640 bits & 4224 bits & 4864 bits \\ \hline [PERSON] et al. [16] & 1184 bits & 1344 bits & 2528 bits \\ \hline Ours & 608 bits & 2528 bits & 3136 bits \\ \hline \hline \end{tabular}
\end{table}
Table 5: Computation cost comparison.  
computation cost. The principal merit of the proposed scheme was resistance against potential attacks in GLOMONET. Therefore, the proposed scheme satisfies the security requirements for roaming service and is suitable for practical mobile environments.  
Conceptualization, S.Y.; Formal analysis, J.L., and Y.P. (YoHan Park); Software, S.Y., and J.L.; Supervision, Y.P. (YoungHo Park); Validation, S.L., B.C., Y.P., (YoHan Park) and Y.P. (YoungHo Park); Writing-original draft, S.Y.; Writing-review and editing, S.L., B.C., Y.P., (YoHan Park) and Y.P. (YoungHo Park). All authors have read and agreed to the published version of the manuscript.  
This research was supported by the Institute for Information & communications Technology Promotion (IITP) grant funded by the Korea government(MIST) (No.2018-0-00312, Developing technologies to predict, detect, respond, and automatically diagnose security threats to automotive Ethernet-based vehicle).  
The authors declare no conflict of interest.