# Video Liveness for Citizen Journalism: Attacks and Defenses

## TL;DR

This paper presents Vamos, a novel video liveness verification system for citizen journalism that uses motion analysis to detect fake videos, demonstrating over 93% accuracy against sophisticated attacks.

## Contribution

Introduces Vamos, the first user-transparent video liveness verification method based on motion, capable of handling arbitrary videos and resisting advanced attacks.

## Key findings

- Vamos achieves over 93% accuracy in verifying video authenticity.
- Motion categories influence verification performance.
- Stationary video segments are more resilient to attacks.

## Abstract

The impact of citizen journalism raises important video integrity and credibility issues. In this article, we introduce Vamos, the first user transparent video "liveness" verification solution based on video motion, that accommodates the full range of camera movements, and supports videos of arbitrary length. Vamos uses the agreement between video motion and camera movement to corroborate the video authenticity. Vamos can be integrated into any mobile video capture application without requiring special user training. We develop novel attacks that target liveness verification solutions. The attacks leverage both fully automated algorithms and trained human experts. We introduce the concept of video motion categories to annotate the camera and user motion characteristics of arbitrary videos. We show that the performance of Vamos depends on the video motion category. Even though Vamos uses motion as a basis for verification, we observe a surprising and seemingly counter-intuitive resilience against attacks performed on relatively "stationary" video chunks, which turn out to contain hard-to-imitate involuntary movements. We show that overall the accuracy of Vamos on the task of verifying whole length videos exceeds 93\% against the new attacks.