Physical layer security (PLS) schemes use the randomness of the channel parameters, namely, channel state information (CSI) and received signal strength indicator (RSSI), to generate the secret keys. There has been limited work in PLS schemes in long-range (LoRa) wide area networks (Lo-RaWANs), hindering their widespread application. Limitations observed in existing studies include the requirement of having a high correlation between channel parameter measurements and the evaluation in either

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... lly indoor or outdoor environments. The real-world wireless sensor networks (WSNs) and LoRa use cases might not meet both requirements, thus making the current PLS schemes inappropriate for these systems. This paper proposes LoRA-LiSK, a practical and efficient shared secret key generation scheme for LoRa networks to address the limitations of existing PLS schemes. Our proposed LoRa-LiSK scheme consists of several preprocessing techniques (timestamp matching, two sample Kolmogorov Smirnov tests, and a Savitzky-Golay filter), multi-level quantization, information reconciliation using Bose-Chaudhuri-Hocquenghem (BCH) codes, and finally, privacy amplification using secure hash algorithm SHA-2. The LoRa-LiSK scheme is extensively evaluated on real WSN/IoT devices in practical application scenarios: 1) indoor to outdoor and 2) long range static and mobile outdoor links. It outperforms existing schemes by generating keys with channel parameter measurements of low correlation values (0.2 to 0.6) while still achieving high key generation rates and low key disagreement rates (10% − 20%). The scheme updates a key in one hour approximately using an application profile with a high transmission rate compared to three hours reported by existing works while still respecting the duty cycle regulation. It also incurs less communication overhead compared to the existing works.