SWARD: A Secure WAke-up RaDio against Denial-of-Service on IoT devices.

Wake-up radios are mechanisms that control the sleep and active modes of energy-constrained Internet of Things (IoT) nodes. These radios detect pre-determined wake-up tokens and switch the devices to an active state. Such systems are vulnerable to a kind of Denial-of-Service attacks called Denial-of-Sleep, where attackers continuously send wake-up tokens to deplete the battery of the nodes. We propose a protocol to mitigate these attacks that includes a novel solution to generate hard-to-guess wake-up tokens at every wake-up. Simulations show that under standard operating conditions, it has a negligible energy overhead (0.03%), while it increases the lifetime of an IoT node by more than 40 times under Denial-of-Sleep attack. Finally we compare our protocol to related work against Denial-of-Sleep attacks, and explain why it is both more resilient and more energy-efficient than existing approaches.