arXiv:2608.03130cs.CRcs.CL2026-08

为长时记忆LLM设计隐私接口,防止属性泄露

DP-MemView: A Memory Interface for Attribute-Level Transcript Privacy in Long-Term LLM Agents

论文配图:DP-MemView: A Memory Interface for Attribute-Level Transcript Privacy in Long-Term LLM Agents
图 1 · 摘自论文原文
  • 用差分隐私选择公开的响应视图,而非直接暴露记忆
  • 每项隐私属性有独立账本,超限则返回通用视图
  • 在保持个性化的同时,有效防止长期对话泄露身份

长期记忆使LLM代理具备持续个性化能力,但重复的记忆条件化响应可能累计暴露受保护属性,即使这些属性从未被明确陈述。我们提出自适应对话隐私问题,并引入DP-MemView,一种差分隐私接口,通过私密选择公开的响应条件视图并仅暴露这些视图(而非原始记忆)给响应模型。每次私密选择均按其与读取集合交集的每个受保护属性计费。基于属性的账本会阻止任何超出额度的选择,并返回固定通用视图。在显式接口契约下,我们证明整个自适应对话满足纯B_a-DP。我们还扩展至跨多个受保护组的存储场景,并量化了观察对话对攻击者先验概率的影响。在控制邻接存储基准和公共语料库迁移任务上,评估了在线与预分配模式下的三种响应模型。两种模式均将对话可区分性维持在随机水平,同时保持目标个性化需求和整体响应质量。进一步诊断显示,移除关键防护机制会导致输出支持不匹配、账本计费缺失、侧信道泄露或长期泄漏增长。

原文摘要 · Abstract (English)

Long-term memory enables persistent personalization in LLM agents, but repeated memory-conditioned responses can cumulatively reveal protected attributes even when they are never stated explicitly. We formalize this threat as adaptive transcript privacy and introduce DP-MemView, a differentially private interface that privately selects public response-conditioning views and exposes those views---rather than raw memory---to the response LLM. Each private selection is charged to every protected attribute whose memory group intersects the read set. Per-attribute ledgers block any selection that would exceed its cap and return a fixed generic view instead. Under an explicit interface contract, we prove pure B_a-DP for the entire adaptive transcript. We also extend the result to stores that differ across multiple protected groups and bound how much observing the transcript can change an adversary's prior odds. We evaluate the online and preallocated modes with three response LLMs on a controlled adjacent-store benchmark and a public-corpus transfer track. Both modes keep transcript distinguishability near chance while preserving target-required personalization and overall response quality. Further diagnostics show that removing key safeguards causes mismatched output support, missing ledger charges, revealing side channels, or growing long-horizon leakage.

隐私保护大模型差分隐私记忆管理

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