TEE-based model protection for on-device LLMs obfuscated only the output side, and that was enough to break it
AspireAI community · arXiv (NeurIPS 2026)
Most Trusted Execution Environment parameter obfuscation applies unilateral matrix transformations to the output side only. The paper identifies the Solution Determinacy Property: the obfuscation secret becomes uniquely determined, exposing the structure of the true key. Under the proposed attacks, GroupCover and ArrowCloak drop to negligible protection, with attack accuracy above 2.4 times the full-shielding black-box baseline and near-complete recovery of model functionality. BiShield-TEE is the fix, jointly obfuscating input and output dimensions so the true key is one of many equally valid candidates, and it confines attack accuracy to the full-shielding baseline with higher inference efficiency on real hardware.
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