## 2 Related Work
[31] proposed a new secure roaming authentication and key negotiation protocol called SRAKN, which enables efficient and fast roaming between users, satellites, and foreign terrestrial control stations (FTCS), and finally negotiates secure session keys. [PERSON] et al. [32] proposed a fast handover authentication protocol for high-speed mobile terminals for railways in SGINs. Their method forms a temporary group of terminals in the same compartment and completes the handover based on preset information. Table 1 shows a summary of therelated works described in this paper. We study their schemes according to four aspects of these related works: performance objective, algorithm/scheme, scenario, and motivation. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Ref.** &
\begin{tabular}{c} **Performance** \\ **Objective** \\ \end{tabular} & **Algorithm/Scheme** & **Scenario** & **Motivation** \\ \hline
[2] & 6G security architecture & - & 6G &
\begin{tabular}{c} Research on 6G security requirements, analyzing 6G security architecture \\ \end{tabular} \\ \hline
[16] & access authentication & bilinear pairing & SIN &
\begin{tabular}{c} Research on group authentication using satellite broadcasting \\ \end{tabular} \\ \hline
[17] & \
\begin{tabular}{c} unified authentication \\ architecture \\ \end{tabular} & - & heterogeneous B5G &
\begin{tabular}{c} Research on a heterogeneous unified authentication \\ architecture \\ \end{tabular} \\ \hline
[18] & access authentication & RLWE & post-quantum era &
\begin{tabular}{c} Research on access authentication against \\ quantum cryptography \\ \end{tabular} \\ \hline
[19] & access authentication & bilinear pairing & SAGIN &
\begin{tabular}{c} Research on satellite multicast authentication protocols \\ \end{tabular} \\ \hline
[20] & access authentication & ECC & SIN &
\begin{tabular}{c} Research on secure access authentication protocols \\ \end{tabular} \\ \hline
[23] & group signature & SGS & - &
\begin{tabular}{c} Research on unlinkable group signatures \\ \end{tabular} \\ \hline
[12] & access authentication & SGS & - &
\begin{tabular}{c} Research on batch \\ authentication scheme for SGS \\ \end{tabular} \\ \hline
[24] & access authentication & SGS & - &
\begin{tabular}{c} Research on signcryption scheme for SGS \\ \end{tabular} \\ \hline
[25] & batch authentication & ECC & VANET &
\begin{tabular}{c} Research on fast and \\ anonymous batch and rebatch \\ authentication \\ \end{tabular} \\ \hline
[26] & batch authentication & ECC & M2M &
\begin{tabular}{c} Research on lightweight group \\ and rebatch authentication \\ \end{tabular} \\ \hline
[27] & access authentication & ECC & IoT &
\begin{tabular}{c} Research on authentication \\ that quickly validates massive \\ requests \\ \end{tabular} \\ \hline
[28] & access and handover authentication & secret sharing & \
\begin{tabular}{c} multi-operator \\ networks \\ \end{tabular} &
\begin{tabular}{c} Research on cross-domain \\ handover authentication \\ \end{tabular} \\ \hline
[29] & access and roaming authentication & ECC and SBC & SGIN &
\begin{tabular}{c} Research on decentralized \\ authentication and charging \\ fairness \\ \end{tabular} \\ \hline
[30] & access and roaming authentication & SGS & SIN &
\begin{tabular}{c} Research on a user \\ cross-domain roaming scheme \\ \end{tabular} \\ \hline
[31] & access and roaming authentication & ECC & SIN &
\begin{tabular}{c} Research on a secure roaming \\ and key agreement scheme \\ \end{tabular} \\ \hline
[32] & access and handover authentication & CRT & HSR and SGIN &
\begin{tabular}{c} Research on efficient \\ authentication and handover \\ of terminals for railways \\ \end{tabular} \\ \hline \hline \end{tabular}  
* there is no relevant statement about this work.  
\end{table} 
Table 1: Summary of related works *.