TOP 文献データベース The Double-edged Sword of LLM-based Data Reconstruction: Understanding and Mitigating Contextual Vulnerability in Word-level Differential Privacy Text Sanitization
Workshop on Privacy in the Electronic Society (WPES)
The Double-edged Sword of LLM-based Data Reconstruction: Understanding and Mitigating Contextual Vulnerability in Word-level Differential Privacy Text Sanitization
Differentially private text sanitization refers to the process of privatizing
texts under the framework of Differential Privacy (DP), providing provable
privacy guarantees while also empirically defending against adversaries seeking
to harm privacy. Despite their simplicity, DP text sanitization methods
operating at the word level exhibit a number of shortcomings, among them the
tendency to leave contextual clues from the original texts due to randomization
during sanitization $\unicode{x2013}$ this we refer to as $\textit{contextual
vulnerability}$. Given the powerful contextual understanding and inference
capabilities of Large Language Models (LLMs), we explore to what extent LLMs
can be leveraged to exploit the contextual vulnerability of DP-sanitized texts.
We expand on previous work not only in the use of advanced LLMs, but also in
testing a broader range of sanitization mechanisms at various privacy levels.
Our experiments uncover a double-edged sword effect of LLM-based data
reconstruction attacks on privacy and utility: while LLMs can indeed infer
original semantics and sometimes degrade empirical privacy protections, they
can also be used for good, to improve the quality and privacy of DP-sanitized
texts. Based on our findings, we propose recommendations for using LLM data
reconstruction as a post-processing step, serving to increase privacy
protection by thinking adversarially.