A self-healing secure group communication framework for resource-constrained IoT devices using decentralised key management and trust-based voting

Group communication in resource-constrained IoT deployments still lacks a dependable answer to insider misbehaviour. Sensor networks that grow to hundreds of heterogeneous nodes cannot always afford the memory and CPU budget that conventional cryptographic machinery demands, and Group OSCORE, while shown to be hardware-feasible, offers little protection once a malicious node has already been admitted to the group: a compromised member can quietly drop everything it is asked to forward and the rest of the network has no built-in way of noticing. We present SecureGroup-IoT , which closes this gap through three components working together: (1) a server-coordinated logical key hierarchy giving \(O(\log N)\) re-keying along with forward and backward secrecy; (2) a BLET-IoT-style trust layer that uses subjective logic to turn raw forwarding observations into calibrated, uncertainty-aware opinions about each node; and (3) a multi-watchdog consensus mechanism that automatically evicts a misbehaving node and triggers the corresponding key rotation. We built and ran the protocol in Contiki-NG 4.0 on emulated Zolertia Zoul hardware inside Cooja. Against an active blackhole attacker, the framework pulled packet delivery ratio back up from 43.7% to 93.4%, with a median isolation time of 22.4 seconds, while adding only 6.4% energy overhead. Total memory footprint came to 17.9 kB, leaving 45% headroom on Class 1 hardware.