## 3 Literature Review
The main idea behind the TSN mechanisms is splitting the network traffic into three types based on priorities (listed in descending order): TT (time-triggered traffic), AVB traffic and BE (best-effort) traffic [33]. New capabilities have enabled usage of Ethernet in different industries (e.g., automotive, automation and aviation) for communication in processes which have hard real-time requirements for video transfer. A sample application where TSN was utilised is presented in [34]. Guaranteed end-to-end latency of 2 ms over seven hops is the main characteristic of this TSN network [35]. Despite performance improvements introduced by time sensitive networking when compared with standard Ethernet, the main area of application of the technology is in industrial local area networks (e.g., real-time systems in a car, plane, etc.). It is also worth noting that in order to establish a time sensitive network, it is necessary to use dedicated network devices, which support this technology. This is due to the fact that the technology is implemented on layer 2 (the MAC layer) of the OSI model [36]. Secure video: Adding encryption to the video signal in order to provide the data security makes real-time video transfer more complex. Encryption of the video stream data has been an active field of research for a long time. The IoVT technology increased the number of video streaming devices on the Internet, which in turn increases the necessity for having high quality security solutions. Existing video encryption solutions differ based on the amount of video stream data that actually gets encrypted. On this basis, there are partial and full video encryptions. With partial techniques, encryption is conducted on part of the data necessary for scrambling the video and making it worthless without decrypting. A full video encryption technique implies encryption of the complete content of the video stream, making it more secure, but at the same time the process of full encryption requires more processing power. Full encryption can be realized by using two techniques called homomorphic and invariant encryption [37]. These two differ by the amount of signal processing, which can be conducted on the encrypted video signal and also differ by efficiency. The first technique is more efficient while the latter one offers more flexibility in terms of signal processing. The ability to process and alter encrypted signals is important in cases where new information needs to be embedded into the stream (e.g., watermark embedding). Depending on the application of encrypted video, both full and partial encryption techniques have drawbacks and benefits. The main drawbacks for full video stream encryption include increased video latency, high required processing power and inability to process encrypted video without decrypting it. For this reason, a lot of effort has been made in algorithms, which can be used for partial encryption of video streams. An algorithm which deals with selective encryption for H264 video streams is published in Ref. [38], while in [39; 40] selective encryption mechanism are proposed to be used mainly with the HEVC (high efficiency video coding) compression standard. In contrast to selective video encryption, work which deals with full encryption of video streams were also published [41]. In Ref. [42], authors propose an algorithm which solves a three-fold goal in video encryption research: high compression, low computation cost and secrecy. The authors use an FPGA platform for implementation of the algorithm and focus on ensuring real-time video delivery. In Ref. [43], authors implemented encryption of real-time video stream by using several different encryption algorithms. Asymmetric key cryptographic transform based on elliptic curve cryptography (ECC) and AES methods were used. The encryption was implemented for the purpose of testing and analysing the performance of different ECC curves, which were then compared with the performance of AES-encrypted and non-encrypted video streams in streaming applications.