# Reliable Integrity Preservation Analysis of Video Contents with Support of Blockchain Systems
###### Abstract
This approach has a drawback: it cannot discriminate in cases in which video contents are preserved without any tampering during the manipulation of video editing tools. To overcome this drawback, we propose another mechanism that traces the integrity preservation of video contents after the target video file is retouched using a video editing tool. Figure 1 shows the trace procedure of integrity preservation for a video file that has been retouched but not tampered with. In the proposed scheme, the front server extracts the software characteristic from the original video and the multimedia contents of original video and those of retouched video. The backend blockchain system verifies the integrity of the original video and stores the integrity verification result of the original video and the comparison result between the original and retouched videos. Then, a user can easily search for the integrity preservation analysis of the original and the retouched video files. In the proposed scheme, the back-end blockchain system takes the role of keeping the core parts of the proposed scheme immutable, while the front-end server takes the role of processing heavy computation, such as comparison operation of video contents and hash operation of video files. If the whole source codes are located in the front-end server, the analysis result becomes changeable whenever the source codes are updated. In order to guarantee the reliability of the proposed scheme, the core parts affecting the analysis result are located in the back-end blockchain system so that they are not allowed to change. To evaluate the feasibility of the proposed scheme, we implement the proposed scheme into a software tool working upon a commercial public blockchain system, _Klayth_[10]. The software module in the front-end server is implemented with the Javascript language, and the software module in the back-end blockchain system, referred to as smart contract program, is implemented with the Solidity language. In the integrity analysis evaluation, the implemented tool verifies the integrity of two hundred original videos and four hundred retouched videos with 100% accuracy. The implemented tool completes the integrity analysis very quickly, within at most one second, because it examines only the metadata of video files and not their multimedia contents. In the evaluation of integrity preservation trace, we find a noticeable phenomenon: the frames of the original video are not exactly the same as their corresponding frames in the retouched video. Even though there is no manipulation when transforming the original video into the retouched video using a video editing tool, the red, green and blue component values in the original video file are slightly different from those in the retouched video file. So, if any difference between an original video and its retouched video is not allowed, we fail to verify the integrity preservation of the video files which have been retouched but not tampered with in all cases. When a proper difference of red, green and blue components in each pixel is allowed, the implemented tool verifies the integrity preservation of retouched video files with 100% accuracy. When obtaining the comparison result between an original video and its retouched video, the execution time of the implemented tool is affected heavily by the size of multimedia contents, and thus increases proportionally to the file size, When searching the comparison result with a hash value of the input video, the execution time of the implemented tool is affected slightly by the size of multimedia contents, and the search operation is completed within, at most, four seconds in our experiments. The contributions of this article are following;  
* This article proposes a trace scheme of multimedia integrity preservation for retouched but not-tampered videos. To the best of our knowledge, this study is the first to record the transforming history from original videos to their retouched videos in order to trace the integrity preservation of the retouched videos.