# Reliable Integrity Preservation Analysis of Video Contents with Support of Blockchain Systems
## 5 Conclusions and Discussions  
In this article, we propose an integrity preservation analysis scheme of video contents with the support of blockchain systems. To guarantee the reliability of the proposed scheme, core source codes of the scheme are stored in their original form in the public blockchain system immutably, so that any user can easily verify the core parts of the scheme. The rest of the codes are stored as a short form of their hash value in the blockchain system so that any user can check their modification time.  
The scheme first examines the software characteristics of digital camera devices and video editing tools in advance, and stores them in the blockchain systems. Next, the scheme extracts the software characteristic from the target video file and compares it with the prepared characteristics in the blockchain system. With a matched characteristic in the blockchain system, the scheme determines the source camera device or the source video editing tool that generates the target video file. In addition, the proposed scheme stores the transformation history of retouched video contents into the blockchain system. The scheme compares the original video and its retouched video frame by frame, and stores the comparison result with a hash value of the retouched video in the blockchain system. Then, the transformation history of the non-original video file can be easily searched in the blockchain system, where the hash value of the video file is used as the index of the searching operation. We implement the proposed scheme into a practical tool on a commercial blockchain system. Experimental results show that the proposed scheme performs the integrity analysis of video files with 100% accuracy and provides the transformation history of retouched video files with 100% accuracy when a proper parameter is given. It is also shown that the proposed scheme completes the integrity analysis within at most one second, and the search operation for transformation history of retouched video files within at most four seconds.  
Although this article deals with only the integrity preservation trace for non-modified transforming from original videos to retouched video, the proposed scheme can be extended to the integrity preservation for modified transforming. Examples of modified transforming with integrity preservation are adding the text subtitle to video frames for language translation and generating a short highlight video from a long video. Additionally, this article addresses only the comparison of image contents, but the proposed scheme is applicable to the comparison of audio contents. This study empirically determines the allowed difference ratio used for comparison between original and retouched videos. We leave the problem of systematically determining the allowed difference ratio for further study. We will also investigate the cost minimization of a blockchain system required to store the core parts in further study.  
Conceptualization, W.Y.L.; Implementation, W.Y.L. and Y.-S.C.; Testing and Validation, W.Y.L. and Y.-S.C.; Writing--Original Draft Preparation, W.Y.L.; Writing--Review and Editing, W.Y.L.; Supervision, W.Y.L. All authors have read and agreed to the published version of the manuscript.  
This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2021R1F1A1045676).  
Not applicable.  
The authors declare no conflict of interest.