Model-Based Privacy-Preserving Knowledge Transfer for Large Language Models

As large language models (LLMs) become more prevalent, effectively utilizing domain-specific knowledge while ensuring privacy has become critical. Existing methods often struggle to balance utility and privacy. For instance, retrieval-augmented generation (RAG) enables LLMs to access domain-specific knowledge but compromises the privacy of sensitive data. On the other hand, differentially private data synthesis techniques offer strong privacy guarantees but often result in poor utility. To address this challenge, we propose Llamdex, a novel framework that enhances LLMs using only models trained on domain-specific data, integrated into LLMs through carefully designed connection modules. Our approach significantly enhances the accuracy of domain-specific tasks, achieving up to a 26% accuracy improvement compared to state-of-the-art data synthesis methods under the same differential privacy constraints. Experimental results show that Llamdex not only improves the accuracy of LLM responses but also maintains comparable inference efficiency to the original LLM, highlighting its potential for real applications.