## 3 Key Technologies of UAV-Assisted SAGINs
### Security Control
#### 3.2.1 Security Attacks  
Cybersecurity attacks can be categorized into two types based on their objectives: obtaining sensitive data and disrupting network systems. Network attackers exploit system vulnerabilities to illegally infiltrate systems and gain access to critical system data and sensitive user information or employ attack methods to damage systems, potentially extorting financial benefits from system operators. Such cyberattacks span various fields, including government, IT, and finance, often leading to service outages and significant financial losses. In UAV-assisted SAGINs, attack methods are more diverse and complex. In addition to traditional cyberattacks faced by communication networks, such as DoS attacks and zero-day exploits, SAGINs encounter new challenges. Low-altitude UAVs \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 \hline
**Key Technologies** & **Ref.** & **Method** & **Attack** & **Contribution** \\ \hline \multirow{8}{*}{Encryption and authentication technology} & [59] & PUF & FA & A lightweight authentication and key agreement protocol based on physically unclonable functions. \\ \cline{2-5}  & [60] & DWT-CT & EA & Developed an encryption scheme based on discrete wavelet transform (DWT) and chaos theory, specifically for data protection in real-time applications in UAVs. \\ \cline{2-5}  & [61] & HF & ZDA & A platform that allows developers to develop private and permitted blockchains with the Hyperledger Fabric framework. \\ \cline{2-5}  & [62] & BTS & ZDA & Proposed a trust management framework based on blockchain timestamp sequences (BTSs), which reflects the performance of UAVs. \\ \cline{2-5}  & [27] & SST & JA & Proposed a blockchain-based drone-assisted cellular network–secure spectrum trading framework. \\ \hline \multirow{8}{*}{Intrusion detection and prevention} & [63] & DRL & JA & An intrusion detection system designed using DRL methods. \\ \cline{2-5}  & [64] & ML & EA & Designed a feature extraction method based on autoencoders, combined with machine learning models for intrusion detection in UAV communications. \\ \cline{2-5}  & [65] & DCNN & EA & Proposed an intrusion detection system based on deep convolutional neural networks. \\ \cline{2-5}  & [66] & CIDS & ZDA & Proposed a collaborative intrusion detection network architecture (CIDS) based on Hyperledger Fabric and Snort IDS. \\ \cline{2-5}  & [67] & ADS & DDoS & A smart-grid DDoS attack tracking scheme using UAV mobility and an adaptive beam search (ADS) algorithm to reconstruct attack paths and accurately locate attack sources is proposed. \\ \hline \multirow{8}{*}{Physical-layer security} & [26] & FSO-RF & EA/JA & A method to achieve secure communication using a hybrid PSO/RF link in two-stage uplink transmission. \\ \cline{2-5}  & [68] & TD3 & JA & A double-delayed deep deterministic policy gradient (TD3) algorithm based on DRL. \\ \cline{2-5}  & [69] & DRT & FA & A GPS spoofing detection and mitigation scheme based on distributed radar tracking (DRT) and data fusion. \\ \cline{2-5}  & [28; 70] & RIS & EA/JA & (1) A joint beam-forming design for an RIS-assisted satellite–terrestrial hybrid relay network. (2) A scheme for enhancing the security of satellite downlink communications using a novel absorbing RIS. \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Significant research on safety control. primarily rely on radio communication and they are vulnerable to channel jamming and GPS spoofing. Furthermore, control commands exchanged between UAVs and ground or space control stations may be intercepted and altered, potentially allowing attackers to hijack UAVs. The primary security attacks on UAV-assisted SAGINs are as follows:  
1. _Jamming Attacks (JAs)_: These involve maliciously injecting high-power signals into communication channels to disrupt communication and interrupt services [27]. Such attacks are common in wireless and military communications. For instance, UAVs in signal-blocked areas may lose access to control signals and data.