In unmanned aerial vehicle (UAV) swarm networks, a group secret key (GSK) is required to enable secured UAV-UAV communications, multicast, and broadcast transmission. Moreover, it can be used for device authentication. Therefore, this paper proposes an efficient GSK protocol denoted as the sequential secret group key (SSGK) algorithm for distributed UAV swarmsecured communications. The proposed protocol utilizes network coding to generate cooperation information that is transmitted on the channel and is uncorrelated with the generated secret key. The proposed protocol depends on the pairwise key generation (PKG) process between pairs of UAVs. However, not all possible pairwise agreements are performed to minimize the time and signaling overhead, i.e., the pairwise key agreement is performed only between selected UAVs as a compromise between the required overhead transmission resources and the achieved redundancy level. The obtained results show that a redundancy level of 4 is sufficient to provide a reliable GSK generation process. The results also show that the performance of the key generation process highly depends on the channelbit error rate (BER), the number of UAVs, and the key length.
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 (LoRaWANs) which hinder their widespread application. Limitations observed in existing studies include the requirement of high correlation between channel parameter measurements for secret key generation in the proposed schemes and the evaluation of the schemes has only been done in either fully 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. By considering the limitations found in existing PLS schemes, this article proposes LoRA-LiSK, a practical and efficient shared secret key generation scheme for LoRa networks. Our proposed LoRa-LiSK scheme consists of several preprocessing techniques (timestamp matching, two sample Kolmogorov–Smirnov tests, and a Savitzky–Golay filter), multilevel 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) LoRa static and mobile outdoor links. It outperforms existing schemes by generating keys with channel parameter measurements of low correlation values (0.2–0.6), while still essentially achieving high key generation rates, and low key disagreement rates (10%–20%). The scheme updates a key in approximately 1 h using an application profile with high transmission rate compared to 3 h reported by existing works while still respecting the duty cycle regulation. It also incurs less communication overhead compared to the existing works.
With the rise of connected vehicular networks, Vehicle-to-Vehicle (V2V) communication has become a fundamental enabler for intelligent transportation systems. However, the open nature of wireless channels introduces risks such as eavesdropping and key compromise. To address these issues, we propose a secure V2V communication scheme based on Physical Layer Key Generation (PLKG) using LoRa technology. The proposed system utilizes Received Signal Strength Indicator (RSSI) measurements between two moving vehicles as the entropy source. To improve the channel correlation, a Savitzky-Golay filter is applied as a preprocessing step. Adaptive multibit quantization is then used to convert the RSSI into binary sequences, followed by the Cascade algorithm for error reconciliation. To enhance randomness, privacy amplification is applied using universal hashing and SHA-1. Finally, the generated key is used for AES-128 encryption. The system is implemented on Raspberry Pi 4B using AcSiP EK-S76SXB and RAK2245 LoRa modules. Experimental validation was conducted in three movement scenarios firstly both vehicle move from opposite-direction at
10 km/hfor
300meters, secondly both vehicle move at the same-direction at
10 km/hfor
800meters, and lastly same as the second scenario but with different speed at
20 km/h. Results shown that the system achieves a reliable key generation rate (KGR) of up to 176075.73 bit/s while maintaining low computation time, demonstrating its feasibility for secure real-time V2V communication.