HE-Guardrail: A Homomorphic Guardrail Against Jailbreak Attacks for Encrypted Large Language Model Inference
HE-Guardrail detects LLM jailbreaks during encrypted inference without decrypting client prompts.
Homomorphic encryption lets a server run an LLM on encrypted inputs but prevents inspection of prompts and responses, so jailbreaks can succeed invisibly. HE-Guardrail evaluates guardrails over ciphertext and homomorphically decides whether the model response is returned. Instantiations using Llama Guard, JBShield, and GradSafe closely reproduce plaintext decisions, with different security, efficiency, and utility trade-offs.
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