# From Bottom of Sea to Space: Quo Vadis IoT? So What About Security?
## 3 Security Challenges and Mechanisms
### IoT in the Sky
#### Internet of Aerial Vehicles  
Air traffic management is becoming an ever-increasing area of focus for aerial vehicles. With this comes the security issues that are beginning to arise as more of these systems are designed. Current systems are unable to handle the amount of communication that will occur as more aerial vehicles need to be managed. The authors of [197] propose a method of advanced automatic-dependent surveillance-broadcasting (ADS-B) that allows for easy tracking and monitoring of aerial vehicles. To do this, the authors take advantage of a grouping-based conflict detection algorithm. The flight paths of aerial vehicles are then predicted using a combination of machine learning algorithms, long short-term memory (LSTM), and deep sentence embedding-based trajectory prediction. Through testing the proposed scheme was proven to be able to detect conflicts within seconds. A drone is an autonomous aerial vehicle. Internet of Drones are used in a variety of application areas, including civilian and military aerial photography, Cloud and Fog computing, Unmanned Aerial Vehicles (UAVs), Wireless Sensor Networks(WSNs), and mobile computing. Some recent research works have been focusing on the Internet of Drones [198]. The following security challenges and mechanisms have been studied in research works focusing on the Internet of Drones (IoD):  
* Security Challenges
* Privacy In recent years, there has been an increase in the use of drones in many different aspects, such as structural evaluations, public safety, and industrial settings. In many cases, the information being relayed back from these drones is sensitive, so it is important to make sure privacy is well-kept. The authors of [199] propose a privacy-aware authenticated key agreement scheme. This scheme does not require drones to store secret keys, which, in turn, creates a method that requires less storage in the limited space of the drones. To the best knowledge of the authors, this is the first time that the physical security of the drone has been studied. Third party communication and mobile edge computing are both supported in the authentication of the UAV. This is performed without losing privacy. In IoD, privacy during communication between a moving point and a ground unit is vital to the safety of the user and the drone. In [200] the authors propose a blockchain-based framework for securely managing data. The scheme is used as an access control between a drone and its ground unit by establishing a session key. All communication is published to the blockchain for management and review. A consensus-based algorithm verifies the information published to the blockchain. The Automated Validation of Internet Security Protocols and Applications (AVISPA) tool is used in testing and proves the security of the proposed scheme. Analysis of the scheme further demonstrates its high level of performance and security. * Security Mechanisms
* Authentication Many of the recently proposed schemes in IoD either degrade the efficiency of these devices or are proven completely insecure. The authors of [201] propose the use of ECC and symmetric key primitives to create a new authentication method between a specific user and the drone. The user is able to access the server through the network and a password. The server then tracks the flying area of the drone and is able to link it to the user once authenticated. To test the security of the method, the authors use the random oracle method. When it comes to authentication in IoD many proposed systems use centralized authentication. The issue with this is that these systems typically have single point of failure and struggle with cross-domain authentication. In [202], the authors propose a blockchain-based cross-domain authentication scheme to be used in tandem with 5G. The issues of storage limitation and authentication latency are areas blockchain struggles with. To mitigate these issues, there is a local private blockchain to support local actions. Only authorized individuals are able to view and manage devices on this.