Stronger Judges Do Not See More: Deployment-Integrity Blindness in LLM Evaluation

Abstract:LLM-agent evaluation reports behavioral scores but leaves the identity of the deployed runtime stack unreported. A tampered deployment that preserves evaluated outputs passes every output-only evaluator. We introduce DIB-Bench, a benchmark that measures this deployment-integrity blindness across 7,560 scored examples, six tamper types, and an evaluator ladder from regex scorers through LLM judges to GPT-5-nano. Stronger evaluators accept more tampered outputs: mean acceptance rises from 88.6% (rule-based) to 94.1% (GPT-5-nano), and a trigger-conditional tamper invisible on the evaluation suite produces 48-100% harmful outputs, rising with model capability. A PAC-style bound shows that tampers with zero output shift are undetectable from outputs at any sample size; a manifest-hash identity channel detects them with zero samples. Behavioral fingerprinting identifies the model component above chance (76.7%) but covers one of six stack components. We also propose a graded deployment-identity descriptor for evaluation reports.

Cryptography and Security (cs.CR); Artificial Intelligence (cs.AI)

arXiv:2610.21135 [cs.CR]

(or arXiv:2610.21135v1 [cs.CR] for this version)

https://doi.org/10.48550/arXiv.2610.21135 Focus to learn more arXiv-issued DOI via DataCite (pending registration)

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