This paper introduces the Sensitive Entity Alias Generator (SEAG), a privacy-preserving framework that empowers users to utilize powerful third-party generators without disclosing sensitive information and demonstrates the success of the SEAG framework.
Abstract
Retrieval-Augmented Generation (RAG) is widely used to improve the performance of Large Language Models (LLMs) in answering user queries. Existing privacy research on RAG has focused on preventing unauthorized users from accessing sensitive data. However, another important problem that is often overlooked in RAG privacy research is that external generators have access to the query and the retrieved documents, which may contain confidential information that could potentially be misused or accessed for unintended purposes. In this paper, we introduce the Sensitive Entity Alias Generator (SEAG), a privacy-preserving framework that empowers users to utilize powerful third-party generators without disclosing sensitive information. SEAG introduces a lightweight model that locates sensitive entities, generates corresponding aliases, and constructs an entity replacement table. The table is used to replace sensitive words in the user's query and in the retrieved documents before they are forwarded to an external generator. For this purpose, two datasets were constructed: one for fine-tuning SEAG models to generate entity replacement tables, and another for evaluating the entire SEAG framework. The experimental results demonstrate the success of the SEAG framework. As for the User metric, which measures the ability of the model to provide a correct response to the user while hiding sensitive information from the external generator, all SEAG models achieved over 80% accuracy. Additional analysis further evaluated the ability of SEAG models Qwen-3, LLaMA-3.2, and Phi-4 to hide all sensitive entities within given documents. The results show good performance with total accuracies of 77.83%, 76.73%, and 74.91%, respectively.
A Prompt-Aware Dynamic Hierarchical Differential Privacy framework (PA-HDP) is proposed, which performs a prompt-aware risk hierarchy to dynamically assess privacy risks under different queries and applies adaptive sensitive entity replacement and exponential mechanism-based text selection to provide differentiated privacy protection while preserving semantic utility.
Gang Zhang, Mingyu Tian, Xu-Kun Luan et al.· arXiv.org· 0 citations
KFS-RAG is proposed, a defense that mitigates information leakage by reformulating the retrieved context by identifying a small set of influential keywords from the retrieved context via an attention rollout plus a causal perturbation mechanism.
Ziliang Zhang, Yubo Zhu, Wei Tong et al.· 0 citations
This study presents a detailed, actionable approach to constructing secure, privacy-focused RAG systems and culminates in the Integrated Privacy-Preserving RAG Framework (IPRAG), a five-tier architecture supported by a three-phase deployment protocol.
Firoz Mohammed Ozman· International Journal of Fro...· 0 citations
Large Language Models (LLMs) such as ChatGPT, Gemini, Claude, etc. have become integral tools for technical writing, software development, and communication. However, these systems, despite privacy assurances, still expose a significant privacy risk. User prompts often contain personally identifiable or proprietary information that is transmitted in plain-text to external providers, where it may be logged or accessed despite opt-out policies. This research aims to address this gap by designing a lightweight local encryption middleware that acts as a privacy firewall between users and remote AI APIs. Before a message is sent, the middleware automatically detects sensitive entities (Personally Identifiable Information or PII) and replaces them with typed placeholders such as [PERSON_1] or [ORG_1]. A local mapping (with optional authenticated encryption at rest) links these placeholders to their original values, allowing the system to reconstruct (rehydrate) the final response once the model replies. This design aims to reduce the exposure of sensitive information in human-readable form while maintaining the AI output. We evaluate the system in terms of detection accuracy, reconstruction fidelity, and utility preservation, demonstrating a practical solution for privacy-preserving LLM interaction.
Aditya Vishwakarma, Wencen Wu· International Conference on...· 0 citations
Applications such as personalized assistance and proprietary document analysis require large language models (LLMs) to generate outputs from private data. Yet powerful LLMs typically cannot be deployed on the resource-constrained devices where private data resides, and uploading private data to cloud-hosted LLMs exposes sensitive information. Recent work addresses this tension with a cloud-edge collaborative decoding paradigm, where private data are kept on the edge with a small language model (SLM) producing next-token distributions, which are fused with predictions from a cloud LLM operating solely on public data. In this paper, we systematically analyze the privacy risks of such a paradigm with a novel evaluation framework using constructed QA datasets, which show that such collaboration can expose substantial private-context information. To address such privacy leakage, we propose CoVeil, a defense mechanism which dynamically optimizes transmitted signals to suppress leakage during decoding time while preserving the collaborative quality. Extensive evaluations demonstrate that CoVeil consistently improves the privacy-utility trade-off over existing baselines by reducing data leakage by up to 87.2%, with minimal accuracy loss.
Ke-Jia Zhang, Tianyuan Zou, Zi-Xuan Gu et al.· 0 citations
Fine-grained access control (FGAC) mechanisms such as row-level security (RLS) and document-level security (DLS) are widely deployed in databases to restrict access to data stored in physical indexing structures shared by multiple users (e.g., in multi-tenant databases, or in the implementation of least-privilege within an organization). FGAC implementations often use post-filtering where untrusted queries run over all data and private results are redacted afterwards. Prior work shows this approach can lead to side-channels that enable attackers to test if a chosen value exists in unseen data. While damaging, prior attacks do not enable the efficient recovery of rich, high-entropy data like full records or text documents. We show these side-channels are more damaging than previously thought. Using rich query interfaces (e.g., range, prefix, and conjunctive predicates), we amplify existence leakage into reconstruction attacks. We do this in two settings: - PostgreSQL (RLS timing). We exploit a timing side-channel and expressive SQL queries (e.g., ranges, conjunctions) to enumerate unknown attribute values and, in turn, full records via binary search over large domains. - Elasticsearch/OpenSearch (DLS scoring). We exploit scoring and prefix-expansion side-channels to recover indexed terms from documents. In some cases, we can extract $n$-grams in the corpus to recover approximate text. Our results show that FGAC side-channels must be evaluated in the presence of rich predicates, which can turn membership tests into scalable reconstruction of high-entropy records.
Zachary Espiritu, David Cash· 0 citations
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