Side-Channel Watermarking for LoRaWAN Using Robust Inter-Packet Timing

Low-data rate networks typically cannot afford the overhead entailed with security measures because of lack of bandwidth. In this paper we propose a method for embedding digital watermarks in LoRaWAN based sensor systems. With the presented approach, the transmitted messages themselves do not need to be modified. Rather, the inter-packet interval between individual packets is used as a side-channel to carry the security-relevant information. We first examine the specific characteristics of LoRaWAN which are typical also for similar low-data rate wireless networks and then present a feasible, lightweight approach for the generation of the digital watermarks. Subsequently, we analyze first simulation results of two different differential methods for the watermark implementation.