Secure Key Exchange in Energy-Harvesting Systems: Implementing Diffie-Hellman for Batteryless Devices

This thesis explores secure key exchange in batteryless devices within energy-harvesting systems, focusing on adapting the Diffie-Hellman (DH) protocol for energy-limited environments. Batteryless devices, which operate by harvesting energy from sources like solar, RF, or kinetic energy, have promising applications in IoT networks and sensor systems. However, they encounter unique challenges due to intermittent power availability, necessitating innovative solutions to maintain data integrity and ensure reliable operations. The thesis begins by introducing batteryless devices and examining the limitations of energy harvesting. Unlike battery-powered devices, these systems are designed to be lightweight and environmentally friendly but are prone to unexpected power losses. Since such devices cannot depend on continuous power, they must address challenges like memory persistence and consistency, especially during power failures. Volatile memory is wiped during outages, while non-volatile memory, though useful for storing state information, must be carefully managed to prevent data corruption. To address these issues, this thesis implements the Diffie-Hellman key exchange protocol, a widely trusted cryptographic method that enables two parties to securely establish a shared symmetric key over an unsecured network. Intermittent operation in batteryless devices, however, complicates the key exchange process. To resolve this, the thesis adapts DH for batteryless systems by implementing a series of checkpoints, allowing the device to save its state at different protocol stages. These checkpoints enable the device to resume from the last saved point if power fails, reducing the need to restart the entire protocol, saving time, and improving energy efficiency. The protocol is structured in a client-server architecture, where the batteryless client device interacts with a continuously powered server. Testing reveals that the modified DH protocol with checkpointing successfully enhances efficiency for batteryless devices, with notable improvements in recovery time and power consumption. These results underscore the protocol’s applicability for real-world scenarios, particularly in low-maintenance IoT systems or remote monitoring applications.