You Had to Be There: Private Video Sharing for Mobile Phones using Fully Homomorphic Encryption
Brent Lagesse, Gabriel Nguyen, Utsav Goswami, Kevin T. Wu · 2021
Smart phones and other small, low-cost video cameras have enabled the creation of billions of hours of video content. Many of these videos contain private content that the users want to share with a limited group of people, not all of whom they know. In this paper, we address the problem of sharing videos from different perspectives of the same event without either party revealing any content of the video until it has been established that the videos were of the same event. To address this problem, we designed and implemented a system that can detect similar videos and efficiently be run under a fully homomorphic encryption scheme on mobile devices. The resulting system was able to achieve a precision of 0.9932 and an F1 score of 0.9797 for determining the same videos. The algorithm was able to test a video in 0.4 seconds on an Android 9.0 Pixel 2 and run end-to-end in 1.5 seconds. As a result, participants in an event can share videos with each other to gain a full perspective of the event without releasing the videos to people who were not present.