# A Survey on Satellite Communication System Security
## 5 Defense in Satellite Communication Systems
### Solutions for Availability
In SCSs, these features are used to enhance the stability and availability of each node, offering solutions for mitigating attacks like DDoS attacks. [PERSON] et al. [80] developed a new security framework for mobile SCS networks (MSNETs) using blockchain technology. This framework addresses security challenges in MSNETs by integrating blockchain with a delay-tolerance network (DTN) architecture and satellite constellation management algorithms. The blockchain method is employed via two key methods: securing data communication within the DTN structure and combining it with satellite constellation management to defend against physical cyber attacks. This approach ensures not only the detection of cyber attacks such as flood attacks but also enhances defense capabilities through improved communication and satellite management. Similarly, ref. [81] introduces a new security architecture for SCS networks using blockchain technology. This approach integrates satellite and ground equipment, with a ground base station processing and recording information in a distributed blockchain to eliminate malicious nodes. The architecture includes key features such as enhanced access control, confidentiality, public key authentication for message source verification, and a decentralized system for data management and authority. Additionally, it manages IoT device communications and control commands, significantly improving communication \begin{table}
\begin{tabular}{c c c c} \hline \hline \multicolumn{2}{c}{**Solution Type**} & \multicolumn{2}{c}{**Pros**} & \multicolumn{1}{c}{**Cons**} \\ \hline \multirow{6}{*}{_Anti-Jamming Techniques_} & Game & Uses advanced technologies like & \multirow{6}{*}{Can be complex and costly to implement.} \\  & theoretic & and robust coding. & & Game-theoretic models may \\  & approaches & & & need extensive computation. \\  & & \multirow{6}{*}{Provides strategic defense mechanisms.} & \multirow{6}{*}{Requires sophisticated} \\  & Filtering & & & against interference. \\  & techniques & & Effectively isolate jamming signals. & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Pros and cons of various defense techniques for jamming attacks in SCSs. security and protection against unauthorized access like DDoS attacks, data theft, and hacking. Ref. [82] proposes an access control and intrusion detection framework, named ACID, for blockchain-based SCSs. This framework introduces a token-based access control mechanism for smart contracts, allowing only authorized users to trigger specific smart contracts and preventing illegal access. Additionally, it incorporates an intrusion detection mechanism capable of effectively detecting malicious attacks on smart contracts. **Secure-Routing-based Mitigation:** Routing and security play crucial roles in wireless networks. Specifically, since routing is fundamental in wireless communication, developing efficient routing strategies is a key element [83]. Recent studies [45; 84; 85] have highlighted attacks on such routing strategies, necessitating protective measures. In SCSs, the limited computational resources and energy efficiency of satellites significantly impact routing, leading to the development of methods that can enhance the routing security. [PERSON] et al. [86] focus on the secure LEO trust-based (SLT) algorithm, designed to secure routing in LEO satellite networks against internal malicious attacks. They utilize a distributed trust evaluation model based on Dempster-Shafer evidence theory, eliminating the need for a centralized infrastructure. This model calculates direct, indirect, and aggregate trust values among satellites to assess their trustworthiness. The SLT algorithm can be integrated with the Orbit Prediction Shortest Path First (OPSPF) [87] routing protocol, enhancing network security by detecting and isolating malicious nodes, thereby improving packet delivery rates and reducing packet loss.