ObfusLM: Privacy-preserving Language Model Service against Embedding Inversion Attacks
Yu Lin, Ruining Yang, Yunlong Mao, Qizhi Zhang, Jue Hong, Quanwei Cai, Ye Wu, Huiqi Liu
Abstract
As the rapid expansion of Machine Learning as a Service (MLaaS) for language models, concerns over the privacy of client inputs during inference or fine-tuning have correspondingly escalated. Recently, solutions have been proposed to safeguard client privacy by obfuscation techniques. However, the solutions incur notable decline in model utility and mainly focus on classification tasks, rendering them impractical for real-world applications. Moreover, recent studies reveal that these obfuscation, if not well designed, is susceptible to embedding inversion attacks (EIAs). In this paper, we devise ObfusLM, a privacy-preserving MLaaS framework for both classification and generation tasks. ObfusLM leverages a model obfuscation module to achieve privacy protection for both classification and generation tasks. Based on (k, 𝜖)-anonymity, ObfusLM includes novel obfuscation algorithms to reach provable security against EIAs. Extensive experiments show that ObfusLM outperforms existing works in utility by 10% with a nearly 80% resistance rate against EIAs.
BibTeX
@inproceedings{lin-etal-2025-obfuslm,
title = "{O}bfus{LM}: Privacy-preserving Language Model Service against Embedding Inversion Attacks",
author = "Lin, Yu and
Yang, Ruining and
Mao, Yunlong and
Zhang, Qizhi and
Hong, Jue and
Cai, Quanwei and
Wu, Ye and
Liu, Huiqi and
Chen, Zhiyu and
Duan, Bing and
Zhong, Sheng",
editor = "Che, Wanxiang and
Nabende, Joyce and
Shutova, Ekaterina and
Pilehvar, Mohammad Taher",
booktitle = "Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)",
month = jul,
year = "2025",
address = "Vienna, Austria",
publisher = "Association for Computational Linguistics",
url = "https://aclanthology.org/2025.acl-long.58/",
doi = "10.18653/v1/2025.acl-long.58",
pages = "1160--1174",
ISBN = "979-8-89176-251-0"
}