EdgeTrustX: A Privacy-Aware Federated Transformer Framework for Scalable and Explainable IoT Threat Detection

Real-time threat detection in Internet of Things (IoT) networks requires scalable, privacy-preserving, and interpretable models capable of operating under strict latency constraints. This paper presents EdgeTrustX, a privacy-aware federated transformer framework that addresses these challenges by combining transformer-based representation learning with federated optimisation, differential privacy, and homomorphic encryption. The framework enables collaborative model training across heterogeneous IoT devices without exposing sensitive local data while maintaining computational feasibility for edge deployment. A multi-head attention mechanism integrated with a secure aggregation protocol supports adaptive feature weighting and privacy-protected parameter exchange. To enhance transparency, an explainability module that combines attention visualisation and SHAP analysis provides interpretable insights into attack patterns and decision boundaries. Extensive experiments on four public IoT benchmark datasets—namely, IoT23, NBaIoT, UNSWNB15, and CICIDS2017—demonstrate that EdgeTrustX achieves an average detection accuracy of 94.7%, closely approaching the centralised transformer baseline of 95.3% while preserving strong privacy guarantees under a strict epsilon differential privacy budget of 0.1. The system reduces membership inference attack success to 52.1%, achieves a 23% improvement in scalability, and maintains an average per-round latency of 449.2 ms, confirming its suitability for real-time operation in large-scale edge networks. The main contributions include (1) a privacy-preserving federated transformer architecture for IoT threat detection, (2) a scalable differential privacy-driven secure aggregation protocol, (3) an explainable AI component enabling transparent threat analysis, and (4) a comprehensive empirical evaluation validating accuracy, scalability, privacy preservation, and interpretability in diverse IoT scenarios.