# A Secure Blockchain-Based Authentication and Key Agreement Scheme for 3 GPP 5G Networks
## 2 Related Work
### AKA Schemes against DoS and DDoS Attacks  
On the other hand, many solutions have been designed to alleviate DoS and DDoS attacks during the UE authentication. Some recent 5G AKA schemes aimed at preventing DoS and DDoS are presented in Table 2. For example, by allowing multiple devices to choose a group leader as an agent, many group-based authentication protocols such as [20; 21] aim to relieve computational burden and signaling overheads while authenticating a mass  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Type**} & \multirow{2}{*}{**Highlights**} & \multicolumn{8}{c}{**Security Features**} \\ \cline{3-10}  & & **FV** & **DA** & **PFS** & **LA** & **DoS** & **DDoS** \\ \hline \multirow{2}{*}{Our Work} & \
\begin{tabular}{c} 5G Initial \\ Authentication \\ \end{tabular} & Decentralized authentications with low overhead & ✓ & ✓ & ✓ & ✓ & ✓ & ✓ \\ \hline [9] & \multicolumn{3}{c}{No single trust authority} & & & & ✓ & ✓ \\ \hline \multicolumn{1}{c}{[10; 11]} & Decentralized authentication to nearby gNBs & ✓ & ✓ & & ✓ & ✓ \\ \hline \multicolumn{1}{c}{[12]} & Removal of obsolete data in blockchains & ✓ & ✓ & & ✓ & ✓ \\ \hline \multicolumn{1}{c}{[13]} & Inter-domain authentication & & & & ✓ & ✓ \\ \hline \multicolumn{1}{c}{[14]} & Improving 5G EAP-AKA\({}^{\prime}\) protocol security & & & ✓ & ✓ & ✓ \\ \hline \multicolumn{1}{c}{[19]} &
\begin{tabular}{c} Formally verified protocol using \\ chameleon signature \\ \end{tabular} & ✓ & ✓ & ✓ & & ✓ & ✓ \\ \hline \multicolumn{1}{c}{[15]} & Efficient handover authentication & ✓ & ✓ & ✓ & ✓ & ✓ \\ \hline \multicolumn{1}{c}{[16]} & \multirow{2}{*}{5G Handover Authentication} & Optimized for frequent handover & & & ✓ & \\ \cline{3-10}  & & Lightweight handover authentication & & & ✓ & \\ \cline{3-10}  & & Traceability for base stations to record & & & ✓ & ✓ & \\ \cline{3-10}  & & malicious devices & ✓ & ✓ & ✓ & ✓ & \\ \hline \hline \end{tabular}
\end{table}
Table 1: Recent works on blockchain-based 5G authentication protocols.  
of devices. Although they can alleviate DoS attacks by including secret keys and short delays in the authentication requests, adversaries can bypass the security mechanism by launching the attacks individually. [PERSON] et al. [22] have proposed to construct an AUSF pool and add a mediator to monitor all AUSFs. Although this provides disruption-free 5G-AKA authentication, it cannot prevent DoS attacks effectively because it is uses 5G-AKA, which is the protocol vulnerable to DoS attacks. Additionally, the bandwidth in the AUSF pool is still finite and expensive, and thus needs more investment. [PERSON] et al. [23] have proposed a lightweight and secure handover authentication scheme based on a prediction of the potential target gNB from all neighbor gNBs in the 5G wireless network. The proposal facilitates fast 5G handover authentication by using time-to-live (TTL) attributes and encrypting the next hop chaining counter (NCC) with the Chinese remainder theorem. There are also some other schemes, including [24; 25; 26; 27; 28], proposed recently to fix other security issues in EPS-AKA and 5G-AKA. However, all of them suffer from single-point-of-failure due to the centralized protocol designs. Thus, all the existing DoS attack prevention schemes cannot provide adequate DoS and DDoS attack prevention.