用对抗性探针检测大模型部署后篡改,保护隐私且无需访问模型权重。
Not to Break, but to Attest: Adversarial Probes for Privacy-Preserving LLM Verification

- 设计对抗性探针,通过输入扰动放大模型输出差异。
- 令牌级探针在黑盒环境下对模型篡改敏感度最高,跨平台稳定有效。
- 结合zk-SNARK实现隐私审计,证明时间仅增加0.76秒,适合实际部署。
大语言模型部署后可能发生行为变更,但常规输出保持不变,给人工智能治理带来挑战,尤其在模型权重专有的情况下。本文提出一种基于zk-SNARK的隐私保护审计框架,通过搜索类对抗样本的探针,放大经批准模型与修改后部署版本之间的逻辑值漂移。该框架在不同访问模式下探索互补的探针类型:基于令牌的探针在黑盒设置下运行,仅需输入接口、分词器和词汇表;基于嵌入的探针需要灰盒访问嵌入接口;应力探针依赖额外接口能力,但无需完整白盒访问模型权重或架构。这一系列设计使探针选择可在灵敏度、访问要求与部署成本间取得平衡。我们在多种大语言模型架构、代表部署后攻击的模型篡改场景及GPU平台上评估了探针构造。实验结果表明,尽管处于黑盒环境,令牌级探针在各类模型与GPU平台上始终表现出最强的平均灵敏度。同时,我们的Groth16 zk-SNARK工作流在探针数量从1增至50时仍具实用性:证明时间由1.02秒升至1.78秒,验证时间保持在约0.84秒,证明大小恒定。
原文摘要 · Abstract (English)
Post-deployment changes to large language models can alter behavior while leaving routine outputs largely unchanged, creating a challenge for AI governance when model weights are proprietary. We present a privacy-preserving zk-SNARK-based audit framework that searches for probes designed in the spirit of adversarial examples to amplify logit drift between an approved model and a modified deployment. Our framework explores complementary probe families under different access models. Token-based probes operate in a black-box setting and require only the input interface, tokenizer, and vocabulary. Embedding-based probes require gray-box access to the embedding interface. Stress probes rely on additional interface capabilities but do not require full white-box access to model weights or architecture. This range allows probe selection to balance sensitivity, access requirements, and deployment cost. We evaluate probe constructions across LLM architectures, model-tampering scenarios representative of post-deployment attacks, and GPU platforms. Importantly, our experimental results demonstrate that token-based probes consistently deliver the strongest mean sensitivity across models and GPU platforms, although operating in a black-box setting. Our Groth16 zk-SNARK workflow remains practical as the probe set scales from 1 to 50, where proving time increases from 1.02 to 1.78 seconds, verification remains near 0.84 seconds, and proof size remains constant.
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