Physical-layer key generation (PKG) leveraging the reciprocity of wireless channel provides an effective approach for key agreement among resource-constrained Internet of Things devices. However, current researches on PKG predominantly focus on pairwise communication scenarios, and there remain challenges in achieving group key generation for multiuser scenarios. In this article, we propose a novel recovery mechanism-driven wireless group key generation protocol to facilitate key sharing in the star network typology. Specifically, the root node will assign each member node its unique group key component before initiating group key distribution. Subsequently, all group key components are distributed to member nodes using a forward error correction mechanism, which helps reduce system overhead. Finally, all member nodes utilize a recovery mechanism and their respective group key component to obtain the same complete group key, thereby achieving group key distribution. Compared to existing schemes, our protocol can avoid the significant information leakage caused by repeated distribution of the same group key, thereby enhancing security. We further design and implement a practical wireless group key generation system using ESP32. Additionally, a group channel state information (CSI) extraction tool for multiuser channel measurements is developed. Experimental results demonstrate that our protocol can generate the group key with high randomness while benefiting from good channel reciprocity, making it suitable for cryptographic applications in multiuser communication scenarios.
Physical-layer key generation (PKG) leveraging the reciprocity of wireless channel provides an effective approach for key agreement among resource-constrained Internet of Things devices. However, current researches on PKG predominantly focus on pairwise communication scenarios, and there remain challenges in achieving group key generation for multiuser scenarios. In this article, we propose a novel recovery mechanism-driven wireless group key generation protocol to facilitate key sharing in the star network typology. Specifically, the root node will assign each member node its unique group key component before initiating group key distribution. Subsequently, all group key components are distributed to member nodes using a forward error correction mechanism, which helps reduce system overhead. Finally, all member nodes utilize a recovery mechanism and their respective group key component to obtain the same complete group key, thereby achieving group key distribution. Compared to existing schemes, our protocol can avoid the significant information leakage caused by repeated distribution of the same group key, thereby enhancing security. We further design and implement a practical wireless group key generation system using ESP32. Additionally, a group channel state information (CSI) extraction tool for multiuser channel measurements is developed. Experimental results demonstrate that our protocol can generate the group key with high randomness while benefiting from good channel reciprocity, making it suitable for cryptographic applications in multiuser communication scenarios.
Physical-layer secret key generation (PSKG) leveraging reciprocal wireless channel has been widely studied in pairwise communication scenarios as it addresses the key distribution problem in traditional security mechanisms. However, PSKG encounters the challenges of low key agreement, information leakage and high system cost when it is extended to produce a secret key for a group of users. In this paper, we propose a lightweight Group secret key generation approach leveraging Non-reconciled received Signal Strength (GNSS). Specifically, pairwise bit sequences with high similarity are firstly extracted and then a group key is securely shared with the protection of these pairwise bit sequences, which prevents the information leakage and sophisticated information reconciliation. Detailed algorithms of GNSS for star and chain networks are presented. Numerical and experimental results demonstrate that GNSS can provide high key agreement, thus enabling key generation technology to be used in a group communication scenario.
In recent years, secret key generation method based on the physical layer of wireless channel has been widely studied. Since Channel State Information (CSI) is a fine-grained characterization of channel information, there are currently many studies using CSI for key generation. However, existing CSI extraction tools have the problem that the time interval between uplink and downlink interaction is uncertain, which may result in insufficient reciprocity of CSI. In this paper, we propose a channel measurement method based on the response mechanism of the IEEE 802.11 protocol, and develop a low-cost and universal CSI extraction tool using ESP32. We further design and implement a wireless key generation system based on the tool. To evaluate the performance of the proposed method, we have conducted extensive experiments in an indoor environment. Results show that our method can obtain highly reciprocal CSI in both static and mobile scenarios and can achieve a high key generation rate at around 1788.23 bits/s.
This paper presents a novel group secret key generation (GSKG) protocol for multi-user wireless systems with a star topology. In contrast to conventional methods relying on pairwise key derivation followed by reconciliation, the proposed approach enables the central node to directly select a group secret key uniformly at random across the full quantization space. This eliminates the need for intermediate pairwise keys, significantly reducing computational complexity, communication overhead, and latency. To ensure consistent group key reconstruction, we introduce two lightweight, non-coding reconciliation techniques: One-Sided Centering (OSC) and Quantization Pattern Alternation (QPA). Unlike coding-based reconciliation in conventional schemes, OSC and QPA allow the central node to transmit helper data – derived from adjusted measurements or shifted quantization grids – to peripheral nodes. This helper data not only aligns their channel observations with the selected quantization region, but also implicitly distributes the group key. Thus, reconciliation and distribution are seamlessly integrated into a unified protocol. The proposed GSKG framework supports both fully and partially cooperative scenarios and remains robust against unreliable or compromised nodes by selectively omitting or perturbing helper data. Furthermore, a concatenation-based group key construction method exploits existing bidirectional channel measurements to generate multiple key segments, enhancing throughput without additional channel probing. Extensive simulations validate the scheme’s performance in terms of key disagreement rate, key generation rate, computational efficiency, and robustness against eavesdropping. The results confirm that the protocol offers high scalability and security, making it a practical and efficient solution for group key establishment in IoT and other resource-constrained wireless applications.
Devices in the Internet of Things (IoT) are usually limited in computing resources and energy capacity, which means that encryption schemes with higher complexity are not suitable for them to ensure secure communication. As a promising solution to this problem, physical layer key generation suggests that shared secret keys can be generated from noisy wireless channel measurements to enhance the security of wireless communications. In this article, we propose a key generation scheme with extremely low implementation complexity, which allows physical layer key generation to be implemented on IoT nodes. First, we preprocess the channel measurements with simple moving average filtering before quantization to improve channel reciprocity. Next, a bidirectional difference quantization scheme is proposed to realize reliable quantization of channel measurements, which is ingenious in that the quantization process does not depend on quantization thresholds, and thus, the mismatched key bits caused by measurements close to quantization thresholds can be effectively avoided. Then, we propose an improved Cascade protocol to achieve lightweight and efficient information reconciliation. The simulation results show that our scheme can well balance the reliability and efficiency of key generation, and has excellent performance in terms of implementation complexity and key randomness.
Internet-of-Things (IoT) networks generally contain resource-constrained devices that require an energy-efficient key generation procedure to producing secure keys at a faster rate. The physical characteristics of the wireless channel can be exploited to secure communication within IoT networks. In particular, secret keys can be generated by leveraging on the randomness of the wireless physical channel between two communicating parties. The conventional mechanism of generating keys at the physical layer, i.e., using channel probing, quantization, information reconciliation, and privacy amplification, may not be preferable for IoT devices. In addition, in some cases IoT devices may be deployed in static environments, wherein the channel coherence time is too high to generate keys at a faster rate and with the desired randomness. This study proposes a mapping table-based key distribution scheme for IoT environments, wherein multiple characteristics of the random channel are combined to improve not only the key generation rate (KGR) but also the key agreement rate (KAR) and bit error rate (BER). In the proposed scheme, both the channel magnitude and the phase are exploited in the key generation process. The proposed scheme is immune to channel estimation errors while providing sufficient randomness in the static environment. Additionally, the scheme is thoroughly investigated for different scenarios including the case of a smarter eavesdropper, which attempts to estimate the channel between the legitimate nodes. This case verifies the robustness of the proposed scheme in different settings and attack models.
Device-to-device communication is increasingly important for emerging wireless applications, including the Internet of Things and industry mobile networks. To establish a secure communication channel between multiple legitimate devices, key agreement is an essential first step. Physical layer channel information is a promising technology for achieving communication security by generating a shared channel key. In this paper, we propose an efficient and random method for generating channel keys based on channel state information (CSI). Firstly, we preprocess the available subcarriers to reduce the correlation of adjacent subcarriers. Secondly, we propose a novel quantization process to generate random and secure channel keys. The part consists of two phases: the quantization phase and the inconsistency removal phase. In the quantization stage, CSI sub carriers are grouped into small blocks, and appropriate thresholds are generated. Then, wireless users quantize the CSI subcarriers into initial bit streams of 0 and 1 with different thresholds. In the inconsistency removal phase, we design an error correction mechanism where wireless users exchange the discarded index sequences in the initial bit streams to achieve key sequence consistency. We implement the proposed scheme using off-the-shelf wireless devices and evaluate its performance. The experimental results show that each CSI packet can produce 30 bits, which have passed the NIST randomness tests.