MemPrivacy: Privacy-Preserving Personalized Memory Management for Edge-Cloud Agents

AuthorsYining Chen, Jihao Zhao, Bo Tang et al.

arXiv 20262026

TL;DR

MemPrivacy uses local typed placeholders plus reversible restoration to reach 85.97 F1 on MemPrivacy-Bench, beating GPT-5.2 by 16.98 points while cutting latency.

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THE PROBLEM

Cloud memory leaks sensitive spans with 75% attack success

Long-term cloud memory exposes PII across logs, vector stores, and reuse, with leakage attacks reaching 75% success and multi-turn attacks up to 69%.

This breaks personalized edge cloud agents, forcing users into self censorship or crude masking that destroys semantics and degrades long term personalization.

HOW IT WORKS

MemPrivacy — local pseudonymization with typed placeholders

MemPrivacy centers on a Local MemPrivacy Model, Four-Level Privacy Taxonomy, Local Secure Mapping DB, and staged Uplink Desensitization and Downlink Restoration.

Think of MemPrivacy as a privacy RAM front end that rewrites secrets into typed handles before sending them to a cloud disk like a card catalog.

This KEY_MECHANISM lets MemPrivacy keep semantic roles for memory retrieval and reasoning that a plain context window with full masking would destroy.

DIAGRAM

Three stage MemPrivacy interaction flow

This diagram shows how MemPrivacy processes an edge user request through uplink desensitization, cloud reasoning, and downlink restoration.

DIAGRAM

MemPrivacy Bench and training pipeline

This diagram shows how MemPrivacy builds MemPrivacy Bench and trains MemPrivacy models with SFT and GRPO reinforcement learning.

PROCESS

How MemPrivacy Handles a Three Stage Lifecycle

  1. 01

    Stage 1 Uplink Desensitization

    MemPrivacy uses the Local MemPrivacy Model and Four-Level Privacy Taxonomy to detect privacy spans and replace them with typed placeholders before cloud upload.

  2. 02

    Stage 2 Cloud Processing

    MemPrivacy sends desensitized inputs so the cloud agent can perform reasoning and memory operations while only seeing semantic placeholders and non sensitive signals.

  3. 03

    Stage 3 Downlink Restoration

    MemPrivacy queries the Local Secure Mapping DB to restore original values, performing low latency placeholder lookup and replacement in the user facing reply.

  4. 04

    MemPrivacy Bench Evaluation

    MemPrivacy evaluates privacy extraction and memory utility on MemPrivacy Bench and PersonaMem v2 using its trained MemPrivacy models and configured masking levels.

KEY CONTRIBUTIONS

Key Contributions

  • 01

    MemPrivacy framework for edge cloud agents

    MemPrivacy introduces local reversible pseudonymization with typed placeholders, combining Uplink Desensitization, Downlink Restoration, and a Local Secure Mapping DB for 3 stage protection.

  • 02

    Four level privacy taxonomy PL1 PL4

    MemPrivacy defines PL1 to PL4 levels, from preferences to credentials, enabling configurable masking policies and differential protection across 50 privacy types per user.

  • 03

    MemPrivacy Bench and trained models

    MemPrivacy builds MemPrivacy Bench with 200 users and 155k+ privacy instances and trains 0.6B 4B MemPrivacy models that reach 85.97 F1 and sub 2.1s latency.

RESULTS

By the Numbers

F1

85.97

+16.98 over GPT-5.2 on MemPrivacy-Bench

Precision

86.86

MemPrivacy-4B-RL vs 65.40 GPT-5.2 on MemPrivacy-Bench

Recall

87.15

MemPrivacy-4B-RL vs 78.13 GPT-5.2 on MemPrivacy-Bench

Time (s)

2.05

Latency per message for MemPrivacy-4B-RL vs 4.62 for GPT-5.2 on MemPrivacy-Bench

These numbers come from MemPrivacy-Bench, a privacy dense benchmark with 29,967 privacy instances, testing span extraction with levels and types. The MAIN_RESULT shows MemPrivacy achieves higher F1 and lower latency than GPT-5.2 and Gemini-3.1-Pro for privacy extraction in realistic dialogues.

BENCHMARK

By the Numbers

These numbers come from MemPrivacy-Bench, a privacy dense benchmark with 29,967 privacy instances, testing span extraction with levels and types. The MAIN_RESULT shows MemPrivacy achieves higher F1 and lower latency than GPT-5.2 and Gemini-3.1-Pro for privacy extraction in realistic dialogues.

BENCHMARK

Privacy extraction performance on MemPrivacy Bench

F1 on MemPrivacy-Bench for MemPrivacy and strong general LLM baselines.

KEY INSIGHT

The Counterintuitive Finding

MemPrivacy-0.6B-RL reaches 84.66 F1 on MemPrivacy-Bench, beating GPT-5.2 at 68.99 F1 while running in only 1.63 seconds.

This is surprising because a 0.6B edge scale MemPrivacy model surpasses frontier general LLMs, showing that specialized privacy training can trump raw parameter count.

WHY IT MATTERS

What this unlocks for the field

MemPrivacy unlocks privacy preserving long term memory where edge devices sanitize and restore user data without sacrificing personalization utility.

Builders can now deploy cloud assisted agents that remember preferences and sensitive facts across sessions while keeping raw secrets off the cloud and under user configurable policies.

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