GaitGuard: Protecting Video-Based Gait Privacy in Mixed Reality

Fuente: arXiv
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Main Authors: Romero, Diana, Markopoulou, Athina, Elmalaki, Salma
Format: Preprint
Published: 2023
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author Romero, Diana
Markopoulou, Athina
Elmalaki, Salma
author_facet Romero, Diana
Markopoulou, Athina
Elmalaki, Salma
contents Mixed Reality (MR) systems capture continuous video streams that expose bystanders' and collaborators' gait patterns -- a biometric revealing sensitive attributes including age, gender, and health conditions. We show that video-based gait profiling achieves 78\% accuracy (15.6$\times$ random chance) on unprotected MR feeds, motivating \textbf{GaitGuard}, a real-time defense operating on a companion mobile device. GaitGuard introduces \textbf{GaitExtract}, an automated gait feature extraction pipeline adapted from clinical analysis for egocentric MR perspectives. Through systematic evaluation of 233 mitigation configurations, we characterize privacy-utility-performance trade-offs. A key insight is that gait features derive primarily from transient events (heel strikes, toe-offs). We exploit this temporal sparsity through adaptive mitigation that selectively processes only gait-critical frames, achieving a 68\% reduction in profiling accuracy while preserving visual quality (SSIM: 0.97) at 29~FPS. \textbf{GaitGuard} scales to 10 simultaneous users with under 10ms latency. A qualitative study of 20-participants confirms that the users preferred a solution such as \textbf{GaitGuard} which provides privacy guarantees.
format Preprint
id arxiv_https___arxiv_org_abs_2312_04470
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle GaitGuard: Protecting Video-Based Gait Privacy in Mixed Reality
Romero, Diana
Markopoulou, Athina
Elmalaki, Salma
Human-Computer Interaction
Cryptography and Security
Mixed Reality (MR) systems capture continuous video streams that expose bystanders' and collaborators' gait patterns -- a biometric revealing sensitive attributes including age, gender, and health conditions. We show that video-based gait profiling achieves 78\% accuracy (15.6$\times$ random chance) on unprotected MR feeds, motivating \textbf{GaitGuard}, a real-time defense operating on a companion mobile device. GaitGuard introduces \textbf{GaitExtract}, an automated gait feature extraction pipeline adapted from clinical analysis for egocentric MR perspectives. Through systematic evaluation of 233 mitigation configurations, we characterize privacy-utility-performance trade-offs. A key insight is that gait features derive primarily from transient events (heel strikes, toe-offs). We exploit this temporal sparsity through adaptive mitigation that selectively processes only gait-critical frames, achieving a 68\% reduction in profiling accuracy while preserving visual quality (SSIM: 0.97) at 29~FPS. \textbf{GaitGuard} scales to 10 simultaneous users with under 10ms latency. A qualitative study of 20-participants confirms that the users preferred a solution such as \textbf{GaitGuard} which provides privacy guarantees.
title GaitGuard: Protecting Video-Based Gait Privacy in Mixed Reality
topic Human-Computer Interaction
Cryptography and Security
url https://arxiv.org/abs/2312.04470