Channel state information (CSI)-based channel key generation technology has been widely studied in recent years, but it lacks the application in multi-user access scenarios, and the commonly used CSI extraction tools are not easy to generalize to Internet of Things (IoT) scenarios. The emerging ESP CSI tool overcomes the limitations of traditional tools, but no one has used it for key generation related research. We transformed ESP CSI tool, proposed a numbered CSI extraction tool for key generation in multi-user access scenarios. Then, we conceived a corresponding key generation scheme based on this tool. Experimental results show that CSI data with high reciprocity can be obtained in different scenarios, and can generate keys with low key disagreement rate (KDR), high randomness, and anti-eavesdropping.
Channel state information (CSI)-based channel key generation technology has been widely studied in recent years, but it lacks the application in multi-user access scenarios, and the commonly used CSI extraction tools are not easy to generalize to Internet of Things (IoT) scenarios. The emerging ESP CSI tool overcomes the limitations of traditional tools, but no one has used it for key generation related research. We transformed ESP CSI tool, proposed a numbered CSI extraction tool for key generation in multi-user access scenarios. Then, we conceived a corresponding key generation scheme based on this tool. Experimental results show that CSI data with high reciprocity can be obtained in different scenarios, and can generate keys with low key disagreement rate (KDR), high randomness, and anti-eavesdropping.
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.
Physical layer encryption is a promising solution to provide transmission security for Internet-of-Things (IoT). To realize physical layer encryption, channel state information (CSI) as a random source to generate secret keys should be exploited. The reciprocity of wireless channel between legitimate communication nodes which is typically assumed for time division duplex (TDD) systems, is of critical importance to ensure the consistency in generated keys at two nodes. However, in practical TDD systems, due to the asynchronous measurement of CSI, the receiver noise and the the difference in hardware, etc., the reciprocity of channel measurements between legitimate parties is hard to be guaranteed, which makes physical layer key generation approach infeasible. To address this issue, we propose a wireless key generation scheme based on deep learning techniques. Firstly, a feature extraction network, which consists of two auto-encoders trained jointly, is developed to extract the common feature from the different yet correlated channel observations at two legitimate nodes, which will be used as the source to generate keys. Then a quantizer with an adaptive guard band width is devised to output a binary secret-key sequence from the feature vector. Numerical results show that the proposed scheme achieves remarkable improvement in terms of key disagreement rate (KDR) and key generation rate (KGR) compared existing counterparts in the literature.
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.
Wireless channel key generation technology is an important mechanism to guarantee the security of wireless network, but influenced by the key length and the actual electromagnetic environment, wireless channel key generation technology is faced with the challenge of high-key generation rate (KGR) and low-key disagreement rate (KDR). The existing key generation methods also lack the full use of the channel state information (CSI). We propose a key generation method based on multisubcarrier phase difference to expand the randomness source dimension, eliminate the phase bias, offset part of the noise influence, and set the threshold screening data to reduce the influence of measurement error. We further propose a key generation method based on resampling of kernel density estimation (KDE), which yields highly reciprocal randomness sources by resampling the results of KDE of phase difference values. To fill the metric gap of whether a method keeps low KDR while increasing the KGR, the evaluation metric of effective improvement ratio (EIR) is proposed. The two methods we proposed have a higher EIR than the method of using multiple-input and multiple-output (MIMO) and increasing the quantization level, achieving the goal of increasing the KGR while maintaining the low KDR. The KGR can reach about 12146 bits/s, and the KDR is 1.83%. The keys obtained by both methods can effectively prevent passive eavesdropping and meet the randomness requirements.
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.
With enhancement in wireless technology, security has become an important part in designing of network. Network security is an important aspect of system administration. We are living in a world where there is access to information anywhere, anytime, be it voice, multimedia or data analytics. This information should be provided to the user with the highest possible security. Thus the information exchanged for communication should be highly secured, authentic and only accessible to the authorised user. Recent research has shown that, this security can be provided through RSS (Received Signal Strength) based key generation techniques for authentication of user. But RSS based key generation technique has a drawback that the key generation rate is very low. RSS based technique is highly applicable for mobile devices. In M2M Communication the devices can be static or mobile based. So we explore a technic which is based on Key generation through CSI (Channel State Information) of a channel. Key generation using CSI information can be efficient in the terms of providing security as they can generate quiet a long key as compared to RSS based technique. We deploy an algorithm as a solution to key generation without using additional hardware for key generation and verify that the malicious user is not able to decode the key sighting to the randomness obtained to our algorithm. The major portion of the algorithm concentrates on making the key random so that the attacker is not able to decode the key within a time span which is vulnerable to the communication. When an attacker tries to use the same algorithm and try to sabotage the communication, due to the property of CSI information of OFDM channel, the generated key will be different. Thus it will not match with the secret key used for actual communication. Hence the user will not be able to hijack the communication.