Abstract
Disaggregated 5G/O-RAN edge multicast spans multiple vendors and administrative domains, creating a need for auditable trust signals that do not expose sensitive evidence or disrupt real-time media delivery. This paper presents ZK-TrustLLM, a three-plane architecture that preserves the real-time DTLS/RTP multicast media path while separating evidence retention from trust verification. The evidence plane stores audit artefacts off-chain using the InterPlanetary File System (IPFS) via content addressing (CIDs), while the trust plane records commitments, proof outcomes, and policy-triggering events on a permissioned blockchain. Zero-knowledge submissions prove that a reported score lies within an admissible range and is cryptographically bound to an evidence commitment, while raw evidence remains off-chain for authorised audit. Trust outputs can then drive multicast control policies such as Logical Key Hierarchy (LKH) rekeying or subgroup isolation. We implement and evaluate a 10-tenant prototype (50 submissions) on a local chain with co-located IPFS, observing predictable confirmation latency (p50=6 ms, p95=7 ms) with stable gas (mean ≈ 137,783). The released artefact includes executable baselines and NDJSON logs to support reproducible evaluation.