Secure Intermittent Computing with ARM TrustZone on the Cortex-M

Computer systems that operate on volatile energy sources typically rely on intermittent computing approaches, which involve checkpointing the system's state and persisting a checkpoint to non-volatile memory before the system loses power, and then restoring this checkpointed state when the power supply becomes available again. This process allows for long-running tasks to make progress, but involves security risks when power interruption is used as an attack vector. Based on earlier work that secures checkpoints and checkpoint restoration on the MSP430 MCU, we implement and evaluate a secure intermittent computing protocol that relies on the security features of TrustZone on a Cortex-M MCU to protect the integrity, authenticity, state continuity, and freshness of checkpointed state. Our results show that checkpoints can be created or restored in 20–40 ms, depending on workload sizes. To the best of our knowledge, our work is the first to implement a complete checkpoint utility for the ARM TrustZone's secure world.