Data security is one of the prime concerns in wireless networks. PLKG has been emerging as an attractive alternative to traditional cryptographic techniques. PLKG is more computationally efficient than cryptography. Moreover, PLKG using Principal component analysis (PCA) as pre-processing may further save computations. This paper proposes three mechanisms to select components of PCA which are based on Information content, Mean and Histfit. Bit Disagreement Rate (BDR) is compared for each mechanism. Histfit based method is found to be best. Since only two components are supposed to be processed for key generation, it is computationally efficient/ power efficient too.
Data security is one of the prime concerns in wireless networks. PLKG has been emerging as an attractive alternative to traditional cryptographic techniques. PLKG is more computationally efficient than cryptography. Moreover, PLKG using Principal component analysis (PCA) as pre-processing may further save computations. This paper proposes three mechanisms to select components of PCA which are based on Information content, Mean and Histfit. Bit Disagreement Rate (BDR) is compared for each mechanism. Histfit based method is found to be best. Since only two components are supposed to be processed for key generation, it is computationally efficient/ power efficient too.
Achieving security in the wireless networks by extracting secure bits using physical layer key generation is one of the emerging ideas. However, for the networks with the resource constraint nodes, the security algorithm should be less computationally complex. This can be achieved by reducing the number of numerical computations or by reducing the dimensionality of input data. In this work, we propose to apply dimensionality reduction by the principal component analysis on the input vector of received signal strength for key generation. We select the principal components extracted from the input vector based on information content & cross correlation, and instead of considering all the column of input vector we consider the column vectors corresponding to a few dominant principal components only, for secure key generation. The bit disagreement performance of the system is improved along with the reduction in several numerical calculations corresponding to the rejected input vectors at the cost of few extra computations. This reduces the computational power significantly as verified by simulation and experimental results with sufficient key randomness.
Summary There has been growing attention in physical layer security (PLS) techniques for wireless networks. PLS techniques are based on physical layer characteristics and are less computationally complex than traditional cryptographic approaches, which work on higher layers of networks. Physical layer key generation (PLKG) is one of the prominent key based PLS techniques that exploits reciprocity and randomness of wireless fading channel to establish secure communication between two transceivers. PLKG system consists of five stages as RSS measurement, its preprocessing, quantization and encoding, key reconciliation, and privacy amplification. Each stage has a substantial role in deciding the performance of PLKG system, but RSS preprocessing offers wide scope in performance improvement for the system. In this work, we propose PLKG system using a new class of preprocessing technique first time, which is nonlinear. We formulated the problem uniquely and considered two nonlinear techniques: nonlinear preprocessing using expander (NLPE) and nonlinear preprocessing using compressor (NLPC). We analyzed the performance of system using NLPE and NLPC and found NLPE is most suitable. Performance of the system is evaluated in terms of bit disagreement rate (BDR) and randomness of keys. Results show that NLPE performs extremely well, as compared with linear approach and without preprocessing approach, especially at low signal to noise ratio (SNR) range. Emerging wireless networks such as internet of things (IoT), centralized radio access network (CRAN), wireless sensor network (WSN), and so forth are being operated at lower transmission power with lightweight hardware. Hence, for such type of power constraint networks, proposed PLKG system with NLPE can be proven a perfect security solution.
Key generation is one of the basic techniques used to realize secure channels in this digital world. This article compares both Quantum Key Distribution (QKD) and Physical Layer Key Generation (PLKG). While QKD can give information-theoretic security by invoking principles of quantum mechanics, PLKG is based on exploiting inherent randomness and reciprocity in wireless channels to extract the key. This study, through simulations, provides a comparative analysis of the security and performance aspects of QKD and PLKG against key rate, error rate, bandwidth, channel loss, and Signal-to-Noise Ratio (SNR). The results demonstrate strong trade-offs between QKD and PLKG in terms of security, practicality, and efficiency, with QKD bringing better guarantees for security but both inherently limited in terms of distance and key rate. On the other hand, PLKG is more readily deployable with higher key rates, based on computational security assumptions. This work provides practical guidelines concerning the applicability of both approaches for specific communication applications based on system requirements for communication security.
Physical layer key generation exploiting inherent channel randomness is an open research area in securing the networks with resource constraint nodes; therefore reduction of numerical computation is desirable to save battery power. However, the correlated components due to colored noise also affect the system performance. In this work, we consider the correlated colored noise components along with the additive white Gaussian noise (AWGN) in the wireless channel and analyze the effect of these correlated components on the system performance. We further propose a hybrid averaging and dimensionality reduction (AvDR), based received signal strength (RSS) preprocessing which is the combination of moving window averaging (Av) and principal component analysis (PCA) as dimensionality reduction technique (DR) to improve the system performance. Further, the system performance was evaluated by numerical simulations, and it is observed that the same improvement in system performance is achieved by generating keys from a fewer number of points selected after PCA as compared to processing all the points. Picking a few of the points in the data sequence instead of all reduces the total number of numerical calculations and saves system power, which is the primary requirement of resource constraint networks like the IoT.
Wireless networks get subjected to the different attacks because of it's open nature. Eavesdropping attack, which occurs at the Physical layer of the OSI model, has a great impact on wireless network security. Conventional security in wireless networks depends on the cryptographic techniques. But in wireless sensor networks where a key management infrastructure may not be present and the power resources are also limited, generating a cryptographic key between two mobile entities becomes difficult. Hence Physical layer Security (PLS) has become a novel research solution. In PLS based key generation, a symmetric secret key is obtained at both the ends of the legitimate users using the properties of wireless channel. The key generation process includes four major blocks namely channel measurement, quantization of input samples, error detection and correction and privacy amplification. The output of quantizer has a great effect on the bit mismatch rate (BMR) between the two legitimate users. It also has an impact on key generation rate (KGR). Hence selecting a proper quantizer becomes very essential. In this paper different Quantization schemes are analyzed to achieve effective PLS between the two legitimate users.
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.