Identity by Design, Demographics by Accident: Demographic Leakage and Suppression in Behavioral Biometric Embeddings

2026-08-28

AI Summary

本文研究了行为生物特征认证系统中敏感人口统计信息的泄露问题，并评估了四种后处理方法来抑制这种泄露，同时保持认证效用。

Abstract

Behavioral biometric authentication (BBA) systems use deep learning models to transform biometric signals, such as eye movements, voice, keystroke/touchstroke dynamics, and gait, into identity embeddings for user authentication. While designed to encode identity, these embeddings may inadvertently reveal sensitive demographic attributes, including gender, age, and height. Consequently, an adversary with access to the authentication model can infer demographic information from biometric signals, including those of users unseen during training or enrollment. In this paper, we present the first systematic audit of demographic leakage in BBA systems, evaluating 11 models across 9 datasets spanning four biometric modalities. We further benchmark four post-hoc suppression methods-Incremental Variable Elimination (IVE), Hilbert-Schmidt Independence Criterion (HSIC), Adversarial Encoder-Decoder (AED), and Protected Attribute Suppression System (PASS) to assess their ability to mitigate demographic leakage while preserving authentication utility. Our analysis reveals substantial variation in leakage and suppressibility across modalities, model architectures, and learning objectives. While voice embeddings exhibit high leakage that can be effectively suppressed, keystroke/touchstroke embeddings exhibit lower leakage but are considerably more difficult to sanitize. These findings highlight a fundamental privacy risk in behavioral biometric authentication and provide insights into the factors governing demographic information suppressibility.

Problem

• Behavioral Biometric Authentication
• Demographic Leakage
• Sensitive Attributes

Innovation

• demographic leakage
• behavioral biometric authentication
• post-hoc suppression methods
• incremental variable elimination
• adversarial encoder-decoder