Regulatory-Gated Zero-Trust Access Control for Cross-Border Data Sharing with Policy-Bound Blockchain Arbitration

Cross-border data access requires regulatory eligibility and current security authorization. We developed a four-state regulatory gate and permissioned-ledger arbitration prototype that binds a signed PERMIT declaration, evaluator attestations, and active policies to one request. A frozen 24-case hold-out agreed with an independent engineering review in 22 cases; no non-PERMIT case was classified as PERMIT. The V3 Besu Quorum Byzantine Fault Tolerance (QBFT) contracts enforce request and deployment binding, freshness, replay checks, current policy reads, and audit consistency. All 36 selected controls passed on both four- and seven-validator networks. Across 18 complete 60 s runs at 10–50 offered transactions per second (tx/s), all 32,400 scheduled transactions confirmed. At 50 offered tx/s, mean load-window throughput was 47.82 and 46.53 tx/s, respectively. Higher rates encountered single-sender transaction-pool admission failures. Validator-stop probes stalled beyond the nominal fault count and committed after delayed recovery. A separate V3/V4 comparison confirmed five acceptance-branch transactions and three V4 reverts. A Besu-backed V4 gateway released a 24-byte synthetic object once, with no additional bytes on replay or after policy change. The gateway used in-memory storage, replay tracking, and sending adapters. These selected checks support the prototype; they do not establish legal correctness, exhaustive security, or production data release.