SC-TOF: A Secure and Reliable Task Offloading Framework for IoT Devices Using Smart Contracts and Edge Computing

In IoT networks, devices often offload computational tasks to nearby edge servers with sufficient resources to enhance the quality-of-service (QoS). When an edge server lacks resources to accept an offloading request, the IoT device must locate an alternative server through other devices. This process poses privacy risks due to the heterogeneous and untrusted nature of intermediary devices, which may expose sensitive information such as user location, identity, task details, or device computing capabilities. These intermediaries may also collude with malicious actors, further compromising security. To address these challenges, we propose SC-TOF—a secure task offloading solution based on smart contracts. SC-TOF employs a multi-signature scheme to securely and reliably identify an appropriate edge server, eliminating the need for untrusted intermediary devices. It ensures that task offloading is completed without disclosing sensitive device or task information. We implemented SC-TOF using the iFogSim simulator and Ethereum blockchain. Simulation results demonstrate completion times of 0.8 seconds for a 20 MB task and 5.2 seconds for a 200 MB task.