A Novel Chaining Encryption Algorithm for LPWAN IoT Network

LPWAN IoT networks (such as Sigfox, LoRaWAN, and NB-IoT) become more applicable every day in the industry. Despite their unique advantages, these technologies have many limitations, including low computing power and transmission rate, and very limited payload size. These limitations cause many challenges in the cryptography such as chaining ciphers mode of encryption. In this mode, a packet loss in the transmission leads to disruption in the ciphers chain and consequently, receiving corrupted messages by the receiver. None of the current encryption approaches can be used in LPWAN due to the serious restrictions on the payload size and the limited downlink connectivity. In this paper, we propose a novel chaining encryption method that can be used in any narrowband and lossy network including LPWAN. The proposed method introduces a module named appropriate key finder (AKF) which assigns a dedicated key to each message using hash functions. The AKF mechanism is based on finding a key which its hash is equal to a part of the message. It can handle message loss and keep parties synchronized without using any part of the payload; however, it fails if a collision is found in the hash function. The proposed method is the first one of its kind that is based on a stochastic approach, instead of the deterministic ones. The paper also reviews the statistical properties of the proposed method and the failure probability. Moreover, the simulation and experiment results of some case studies are presented to show the efficiency of the method in practice.