Privacy-Preserving LLMs Routing

Fuente: arXiv
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Autori principali: Wu, Xidong, Zhang, Yukuan, Ji, Yuqiong, Shirkavand, Reza, Lou, Qian, Gao, Shangqian
Natura: Preprint
Pubblicazione: 2026
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author Wu, Xidong
Zhang, Yukuan
Ji, Yuqiong
Shirkavand, Reza
Lou, Qian
Gao, Shangqian
author_facet Wu, Xidong
Zhang, Yukuan
Ji, Yuqiong
Shirkavand, Reza
Lou, Qian
Gao, Shangqian
contents Large language model (LLM) routing has emerged as a critical strategy to balance model performance and cost-efficiency by dynamically selecting services from various model providers. However, LLM routing adds an intermediate layer between users and LLMs, creating new privacy risks to user data. These privacy risks have not been systematically studied. Although cryptographic techniques such as Secure Multi-Party Computation (MPC) enable privacy-preserving computation, their protocol design and implementation remain under-explored, and naïve implementations typically incur prohibitive computational overhead. To address this, we propose a privacy-preserving LLM routing framework (PPRoute). PPRoute includes multiple strategies to speed up encoder inference and nearest neighbor search under the MPC and maintain the quality of LLM routing. First, PPRoute uses MPC-friendly operations to boost the encoder inference. Second, PPRoute uses a multiple-step model training algorithm to maintain routing quality despite the constraints of the encrypted domain. Third, PPRoute proposes an unsorted Top-k algorithm with $O(1)$ communication complexity for secure sorting in model search, significantly reducing communication latency. Across different datasets, PPRoute achieves the performance of plaintext counterparts, while achieving approximately a 20$\times$ speedup over naïve MPC implementations.
format Preprint
id arxiv_https___arxiv_org_abs_2604_15728
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Privacy-Preserving LLMs Routing
Wu, Xidong
Zhang, Yukuan
Ji, Yuqiong
Shirkavand, Reza
Lou, Qian
Gao, Shangqian
Cryptography and Security
Artificial Intelligence
Large language model (LLM) routing has emerged as a critical strategy to balance model performance and cost-efficiency by dynamically selecting services from various model providers. However, LLM routing adds an intermediate layer between users and LLMs, creating new privacy risks to user data. These privacy risks have not been systematically studied. Although cryptographic techniques such as Secure Multi-Party Computation (MPC) enable privacy-preserving computation, their protocol design and implementation remain under-explored, and naïve implementations typically incur prohibitive computational overhead. To address this, we propose a privacy-preserving LLM routing framework (PPRoute). PPRoute includes multiple strategies to speed up encoder inference and nearest neighbor search under the MPC and maintain the quality of LLM routing. First, PPRoute uses MPC-friendly operations to boost the encoder inference. Second, PPRoute uses a multiple-step model training algorithm to maintain routing quality despite the constraints of the encrypted domain. Third, PPRoute proposes an unsorted Top-k algorithm with $O(1)$ communication complexity for secure sorting in model search, significantly reducing communication latency. Across different datasets, PPRoute achieves the performance of plaintext counterparts, while achieving approximately a 20$\times$ speedup over naïve MPC implementations.
title Privacy-Preserving LLMs Routing
topic Cryptography and Security
Artificial Intelligence
url https://arxiv.org/abs/2604.15728