Wireless secret key generation exploits unpredictable multi-path features from wireless channel to achieve high secure key bits. Most of the existing wireless secret key generation methods require information reconciliation process to correct discrepant key bits between the keying parties, which reveals information to the eavesdroppers and increases the system complexity. This paper introduces an integrated wireless secret key based transmission (WSKT) scheme for machine to machine (M2M) communications, using nonreconciled key bits generated from wireless channels without information reconciliation but sharing the error correction capability of channel coding. Polar code and stream encryption are employed to achieve secure communication. Extensive numerical simulations demonstrate that the proposed WSKT can achieve secure M2M communications which only causes a slight degradation on the system performance.
Wireless secret key generation exploits unpredictable multi-path features from wireless channel to achieve high secure key bits. Most of the existing wireless secret key generation methods require information reconciliation process to correct discrepant key bits between the keying parties, which reveals information to the eavesdroppers and increases the system complexity. This paper introduces an integrated wireless secret key based transmission (WSKT) scheme for machine to machine (M2M) communications, using nonreconciled key bits generated from wireless channels without information reconciliation but sharing the error correction capability of channel coding. Polar code and stream encryption are employed to achieve secure communication. Extensive numerical simulations demonstrate that the proposed WSKT can achieve secure M2M communications which only causes a slight degradation on the system performance.
Focusing on the problem of information leakage and communication cost in information reconciliation, this paper introduces a non-reconciliation secret Keys based transmission scheme (NASKT) for machine to machine(M2M) communications in Internet of Things (IoT) networks, which uses polar codes to guarantee no error transmission. First, the improved Kalman filter preprocessing algorithm is used to reduce the quantized bit error rate (QBER). Then, QBER is modeled as the transmission bit error rate of the additional white Gaussian noise (AWGN) channel. Finally, the polar codes are designed based on the equivalent AWGN channel and system performance requirements to guarantee the security of transmitted information. Numerical simulations verify that the secure M2M transmission scheme based on the Non-reconciliation secret Keys using polar codes can realize the One-Time Pad lightweight security.
Physical-layer key generation technology requires information reconciliation to correct channel estimation errors between two legitimate users. However, sending the reconciliation signals over the public channel increases the communication overhead and the risk of information leakage. Aiming at the problem, integrated secure communication schemes using non-reconciled keys have attracted extensive attention. These schemes exploit channel coding to correct both inconsistent keys and transmission error bits. Meanwhile, more redundant code bits must be added to correct errors, which results in a lower secure transmission rate. To address the problem, we analyze the merit of channel correlation between non-reconciled key generation and secure transmission. Inspired by this, we propose a non-reconciled physical-layer keys-assisted secure communication scheme based on channel correlation. First of all, the signal frame is designed to make use of channel correlation between non-reconciled key generation and secure transmission. Based on the channel correlation, non-reconciled keys are then generated from the wireless channel to encrypt transmitted data. Moreover, an adaptive coding algorithm based on the equivalent channel is presented to encode the data bits before encryption, to guarantee reliable transmission. Finally, theoretical analysis and simulations demonstrate the significant performance of the proposed scheme in terms of low bit error ratio and high secure transmission rate.
Due to the broadcast nature of the wireless medium, private communications are easily eavesdropped. This has spurred extensive research into secret key establishment using physical layer characteristics of wireless channels. In all these schemes, the shared secret keys directly originate from the physical features of the real wireless channel, which is highly dependent on the communication environment nearby. Also, previous schemes require performing information reconciliation, which increases both the costs of key establishment and the risk of key leakage over the not yet secured channel. In this paper, we exhibit a novel wireless key establishment method allowing the transmitter to specify arbitrary content as the secret key and cause the receiver to obtain the same key by using a channel manipulation technique. At the same time, eavesdroppers are prevented from deriving the secret key. We furthermore exploit the transmitter's ability to specify any content as the key by enabling the transmitter to apply error-correction code to the key. This means the receiver can automatically detect and correct any mismatched bits without sending key-related information back to the transmitter over the public channel. Experimental results demonstrate that the our key establishment method reaches a success rate as high as 91.0% for establishing a 168-bit key between the transmitter and the receiver, and meanwhile the chance that the eavesdropper can infer the key in meter-order range of the receiver is subdued into the range of 0∼0.10%.
Physical layer security (PLS) of wireless communications is becoming increasingly significant with the advent of 6G. The reconciliation of channel-based secret key generation (SKG) methods is necessary to avoid inconsistencies after key generation, resulting in increased communication overhead, leakage of key information, and reduced security performance. This paper proposes a fuzzy secret key generation (FSKG) method that does not require the legitimate user to perform a consistency check after fuzzy extraction of the phase, which is used directly to encrypt the constellation rotation of the key. The proposed scheme allows users to code-decode the key bits to reduce the transmission error probability and improve the key consistency, and the simulation results prove that the proposed FSKG scheme outperforms traditional SKG schemes like CQA and CQG. The simulation results also indicate that the best secure key rate can be achieved by applying PSK modulation.
As an alternative and appealing approach to providing information security in wireless communication systems, secret key generation at physical layer has demonstrated its potential in terms of efficiency and reliability over traditional cryptographic methods. Without the necessity of a management centre for key distribution or reliance on computational complexity, physical layer key generation protocols enable two wireless entities to extract identical and dynamic keys from the randomness of the wireless channels associated with them.\nIn this thesis, the reliability of secret key generation at the physical layer is examined in practical wireless channels with imperfect channel state information (CSI). Theoretical analyses are provided to relate key match rate with channel's signal-to-noise ratio (SNR), degrees of channel reciprocity, and iterations of information reconciliation.\nIn order to increase key match rate of physical layer secret key generation, improved schemes in the steps of channel estimation and sample quantization are proposed respectively. In the channel estimation step, multiple observations of the wireless channels are integrated with a linear processor to provide a synthesized and more accurate estimation of the wireless channel. In the sample quantization step, a magnitude based quantization method with two thresholds is proposed to quantize partial samples, where specific quantization areas are selected to reduce cross-over errors. Significant improvements in key match rate are proven for both schemes in theoretical analysis and numerical simulations. Key match rate can even achieve 100% in both schemes with the assistance of information reconciliation process.\nIn the end, a practical application of physical layer secret key generation is presented, where dynamic keys extracted from the wireless channels are utilized for securing secret data transmission and providing efficient access control.
Wireless networks are vulnerable to various attacks due to their open nature, making them susceptible to eavesdropping and other security threats. Eavesdropping attack takes place at the physical layer. Traditional wireless network security relies on cryptographic techniques to secure data transmissions. However, these techniques may not be suitable for all scenarios, especially in resource-constrained environments such as wireless sensor networks and adhoc networks. In these networks having limited power resources, generating cryptographic keys between mobile entities can be challenging. Also, the cryptographic keys are computationally complex and require key management infrastructure. Physical Layer Key Generation (PLKG) is an emerging solution to address these challenges. It establishes secure communication between two users by taking advantage of the wireless channel's inherent features. PLKG process involves channel probing, quantization, information reconciliation (IR) and privacy amplification to generate symmetric secret key. The researchers have used various PLKG techniques to get the secret key, sTop of Form till they face problems in the IR scheme to obtain symmetric keys between the users who share the same channel for communication. Both the code based and protocol based methods proposed in the literature have advantages and limitations related to their performance parameters such as information leakage, interaction delay and computation complexity. This research work proposes a novel IR mechanism that combines the protocol and code-based error correction methods to obtain reduced Bit Mismatch Rate (BMR), reduced information leakage, reduced interaction delay, and reduced computational time to enhance physical layer secret key's quality. In the proposed research work, the channel samples are generated using the Received Signal Strength (RSS) and Channel Impulse Response (CIR) parameters. These samples are quantized using Vector Quantization with Affinity Propagation Clustering (VQAPC) method to generate the preliminary key. The samples collected by the two users who wish to communicate, (for example Alice and Bob) will be different due to noise in the channel and hardware limitations. Hence their preliminary keys will be different. Removing this discrepancy between Bob's and Alice's initial keys, using novel Hybrid Protocol and Code related Information Reconciliation (HPC-IR) scheme to generate error corrected key, is the most important contribution of this research work. This key is further encoded by the MD5 hash function to generate a final secret key for exchanging information between two users over the wireless channel. It is observed that the proposed HPC-IR scheme achieves BMR of 19.4%, information leakage is 0.002, interaction delay is 0.001 seconds and computation time is 0.02 seconds.