## 3 Literature Review
Real-time is defined as continuous flow of the media stream over the Internet where the content is presented before it has been downloaded completely. End-to-end delay, jitter, packet loss, encryption and decryption times and data rates were measured and the results were analysed for a total of 18 tested curves and for the case with no encryption. All tests were conducted on an institutional LAN (local area network) and by using MJPEG for encoding the video. The RTSP (real-time streaming protocol) [44] was used for transferring the video and full encryption of the video stream data was conducted. The presented end-to-end delay values do not exceed 10 ms for any curve. The encryption time of AES was found to be in sub-millisecond range. It is worth noting that in the paper there are no details about the technique used for delay measurement. The encryption technique presented in Ref. [45] was applied to video stream data and transferred over the Internet using software designed to support video and network latency measurement. The stream was encrypted by using the efficient high speed AES algorithm, which is considered to be the most suitable for encryption of the real-time video in terms of speed and frame size overhead [46]. The algorithm is implemented on a LabVIEW FPGA platform [14]. Implementation of the algorithm on hardware is mandatory for real-time performance of the encryption, especially in the case of full video stream encryption. This work provides a detailed technique for secure video transmission with thorough analysis of latency. Video and network latencies were simultaneously measured by using the software application designed/presented in this paper. While the tools presented in [18; 20; 21] provide a means for video latency measurement, none of the listed papers explicitly deal with encrypted video. Use of time sensitive networks represent an interesting approach, especially because the packet delivery is guaranteed and delivery takes place within bounded time. However, they can only be applied on video applications, which are running inside controlled environments (LAN in a car or in industrial applications). Since communication over the Internet is the focus of this paper, the usage of time sensitive networks becomes unfeasible. This paper deals with fully encrypted video streams, which represent a more secure option when compared with partially encrypted video. For this reason, dedicated FPGA platforms were used. End-to-end latency for various elliptic curves in real-time encryption and streaming applications was measured and analysed in [43], but these tests were conducted within an isolated LAN. In addition, no video latency was measured and analysed. Publications which are most relevant to this work are listed in Table 1. The classification was made based on the following criteria: Network type determines whether the papers deal with LAN or Internet; time-sync provides information about the way of synchronising time; latency type, which was measured and presented, is listed in column \"Latency\"; information about the encryption algorithm used is given in the \"Encryption\" column and the column titled \"Latency\" lists best achieved results. The only comparable results, to those presented in this section, are the ones which were published in our previous work [12].