Concept-Aware Privacy Mechanisms for Defending Embedding Inversion Attacks

Fuente: arXiv
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Auteurs principaux: Tsai, Yu-Che, Hsiao, Hsiang, Chen, Kuan-Yu, Lin, Shou-De
Format: Preprint
Publié: 2026
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author Tsai, Yu-Che
Hsiao, Hsiang
Chen, Kuan-Yu
Lin, Shou-De
author_facet Tsai, Yu-Che
Hsiao, Hsiang
Chen, Kuan-Yu
Lin, Shou-De
contents Text embeddings enable numerous NLP applications but face severe privacy risks from embedding inversion attacks, which can expose sensitive attributes or reconstruct raw text. Existing differential privacy defenses assume uniform sensitivity across embedding dimensions, leading to excessive noise and degraded utility. We propose SPARSE, a user-centric framework for concept-specific privacy protection in text embeddings. SPARSE combines (1) differentiable mask learning to identify privacy-sensitive dimensions for user-defined concepts, and (2) the Mahalanobis mechanism that applies elliptical noise calibrated by dimension sensitivity. Unlike traditional spherical noise injection, SPARSE selectively perturbs privacy-sensitive dimensions while preserving non-sensitive semantics. Evaluated across six datasets with three embedding models and attack scenarios, SPARSE consistently reduces privacy leakage while achieving superior downstream performance compared to state-of-the-art DP methods.
format Preprint
id arxiv_https___arxiv_org_abs_2602_07090
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Concept-Aware Privacy Mechanisms for Defending Embedding Inversion Attacks
Tsai, Yu-Che
Hsiao, Hsiang
Chen, Kuan-Yu
Lin, Shou-De
Cryptography and Security
Artificial Intelligence
Text embeddings enable numerous NLP applications but face severe privacy risks from embedding inversion attacks, which can expose sensitive attributes or reconstruct raw text. Existing differential privacy defenses assume uniform sensitivity across embedding dimensions, leading to excessive noise and degraded utility. We propose SPARSE, a user-centric framework for concept-specific privacy protection in text embeddings. SPARSE combines (1) differentiable mask learning to identify privacy-sensitive dimensions for user-defined concepts, and (2) the Mahalanobis mechanism that applies elliptical noise calibrated by dimension sensitivity. Unlike traditional spherical noise injection, SPARSE selectively perturbs privacy-sensitive dimensions while preserving non-sensitive semantics. Evaluated across six datasets with three embedding models and attack scenarios, SPARSE consistently reduces privacy leakage while achieving superior downstream performance compared to state-of-the-art DP methods.
title Concept-Aware Privacy Mechanisms for Defending Embedding Inversion Attacks
topic Cryptography and Security
Artificial Intelligence
url https://arxiv.org/abs/2602.07090