# Random Routing Algorithm for Enhancing the Cybersecurity of LEO Satellite Networks
## 1 Introduction
In [27], the authors have studied beamforming and artificial noise methods for securing hybrid satellite-terrestrial networks. The investigation of the secrecy performance of a satellite wiretap channel assuming a Shadowed Rician fading is performed in [28]. In [29], the authors have investigated the physical layer security performance of hybrid satellite and a free-space optical (FSO) cooperative system. In [30], the Doppler shift and received power characteristics of an LEO satellite are used to differentiate between the legitimate and illegitimate satellites using support vector machines. On the other hand, some of the works that focus on cryptography techniques to secure satellite communication systems include: a demonstration scheme for an architecture of a satellite communication using the SAFEcrypto cryptographic solutions [31], utilization of elliptic curve cryptography in the design of a three-factor authentication protocol for satellite communications that is meant to secure the communications against well-known attacks [32], a novel encryption algorithm using XOR operation [33], and a parallel architecture Authenticated Encryption (AE) algorithm for high-data throughput optimized for satellite applications [34]. However, as the communication systems will evolve to the future generation of communication networks, e.g., B5G and 6G, we will need various cross-layer solutions to address the cyberattacks on the densely connected network. More recently, several works began to appear that focus on securing satellite communications in a scenario with respect to DoS/DDoS attacks using the network layer solution. A proof-of-concept was introduced in ICARUS dealing with distributed denial-of-service attacks in the context of LEO satellite networks [8]. In [35], the authors have described mechanisms for supporting Quality-of-Service (QoS) strategies that consider the properties of LEO satellite networks and provide an explanation about several QoS routing strategies as well as their difference from traditional best-effort routing algorithms. In [36], the authors have proposed a strategy named Directed Percolation Routing (DPR) that they used for providing Ultra-Reliable and Low-Latency Communication (URLLC). In [37], a lightweight risk avoidance routing algorithm is proposed to avoid forwarding the user's data in a high-risk area. In [38], the authors have used an active distributed QoS routing strategy with consideration being given to the link duration to find the optimum path. In this work, we address the DDoS attacks on LSNs based on a network layer solution by proposing a random routing algorithm. The algorithm randomly selects among many algorithms to choose with a weighted probability distribution. This ensures that the cost of attacks launched from several bots leading to a DDoS attack is increased due to the increased uncertainty in the LSN routing algorithm. The network layer solution proposed in this work will be applicable for the increasing modern dense network of LEO satellites vulnerable to DDoS attacks. In Figure 1, we show the scenario depicting the launch of a DDoS attack from several compromised bots against LEO satellite networks. The contribution of the article can be summarized as follows:  
1. We propose a k-RAND algorithm that selects from one of the four algorithm--k-DG, k-DS, k-SP, and k-LO--to maximize the average cost of the attacks while maintaining the functionality of the LEO satellite communication network. 2. To optimize the performance of our proposed algorithm, we formulate a Bayesian optimization problem that will maximize the average cost of the routing algorithm for DDoS attacks. 3. We show that the average cost of the DDoS attacks on the satellite network is enhanced with the optimized k-RAND algorithm. The rest of the article is organized as follows: In Section 2, we briefly discuss various kinds of cyberattacks on an information system in the context of satellite communication networks.